1
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Dey R, Raghuwanshi R. An insight into pathogenicity and virulence gene content of Xanthomonas spp. and its biocontrol strategies. Heliyon 2024; 10:e34275. [PMID: 39092245 PMCID: PMC11292268 DOI: 10.1016/j.heliyon.2024.e34275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 06/24/2024] [Accepted: 07/07/2024] [Indexed: 08/04/2024] Open
Abstract
The genus Xanthomonas primarily serves as a plant pathogen, targeting a diverse range of economically significant crops on a global scale. Xanthomonas spp. utilizes a collection of toxins, adhesins, and protein effectors as part of their toolkit to thrive in their surroundings, and establish themselves within plant hosts. The bacterial secretion systems (Type 1 to Type 6) assist in delivering the effector proteins to their intended destinations. These secretion systems are specialized multi-protein complexes responsible for transporting proteins into the extracellular milieu or directly into host cells. The potent virulence and systematic infection system result in rapid dissemination of the bacteria, posing significant challenges in management due to complexities and substantial loss incurred. Consequently, there has been a notable increase in the utilization of chemical pesticides, leading to bioaccumulation and raising concerns about adverse health effects. Biological control mechanisms through beneficial microorganism (Bacillus, Pseudomonas, Trichoderma, Burkholderia, AMF, etc.) have proven to be an appropriate alternative in integrative pest management system. This review details the pathogenicity and virulence factors of Xanthomonas, as well as its control strategies. It also encourages the use of biological control agents, which promotes sustainable and environmentally friendly agricultural practices.
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Affiliation(s)
- Riddha Dey
- Department of Botany, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
| | - Richa Raghuwanshi
- Department of Botany, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
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2
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Timilsina S, Kaur A, Sharma A, Ramamoorthy S, Vallad GE, Wang N, White FF, Potnis N, Goss EM, Jones JB. Xanthomonas as a Model System for Studying Pathogen Emergence and Evolution. PHYTOPATHOLOGY 2024; 114:1433-1446. [PMID: 38648116 DOI: 10.1094/phyto-03-24-0084-rvw] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
In this review, we highlight studies in which whole-genome sequencing, comparative genomics, and population genomics have provided unprecedented insights into past and ongoing pathogen evolution. These include new understandings of the adaptive evolution of secretion systems and their effectors. We focus on Xanthomonas pathosystems that have seen intensive study and improved our understanding of pathogen emergence and evolution, particularly in the context of host specialization: citrus canker, bacterial blight of rice, and bacterial spot of tomato and pepper. Across pathosystems, pathogens appear to follow a pattern of bursts of evolution and diversification that impact host adaptation. There remains a need for studies on the mechanisms of host range evolution and genetic exchange among closely related but differentially host-specialized species and to start moving beyond the study of specific strain and host cultivar pairwise interactions to thinking about these pathosystems in a community context.
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Affiliation(s)
- Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Amandeep Kaur
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Anuj Sharma
- Department of Horticultural Sciences, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | | | - Gary E Vallad
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | - Nian Wang
- Department of Microbiology and Cell Science, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - Frank F White
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
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3
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Chen JR, Aguirre-Carvajal K, Xue DY, Chang HC, Arone-Maxwell L, Lin YP, Armijos-Jaramillo V, Oliva R. Exploring the genetic makeup of Xanthomonas species causing bacterial spot in Taiwan: evidence of population shift and local adaptation. Front Microbiol 2024; 15:1408885. [PMID: 38846563 PMCID: PMC11153759 DOI: 10.3389/fmicb.2024.1408885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 05/13/2024] [Indexed: 06/09/2024] Open
Abstract
The introduction of plant pathogens can quickly reshape disease dynamics in island agro-ecologies, representing a continuous challenge for local crop management strategies. Xanthomonas pathogens causing tomato bacterial spot were probably introduced in Taiwan several decades ago, creating a unique opportunity to study the genetic makeup and adaptive response of this alien population. We examined the phenotypic and genotypic identity of 669 pathogen entries collected across different regions of Taiwan in the last three decades. The analysis detected a major population shift, where X. euvesicatoria and X. vesicatoria races T1 and T2 were replaced by new races of X. perforans. After its introduction, race T4 quickly became dominant in all tomato-growing areas of the island. The genomic analysis of 317 global genomes indicates that the Xanthomonas population in Taiwan has a narrow genetic background, most likely resulting from a small number of colonization events. However, despite the apparent genetic uniformity, X. perforans race T4 shows multiple phenotypic responses in tomato lines. Additionally, an in-depth analysis of effector composition suggests diversification in response to local adaptation. These include unique mutations on avrXv3 which might allow the pathogen to overcome Xv3/Rx4 resistance gene. The findings underscore the dynamic evolution of a pathogen when introduced in a semi-isolated environment and provide insights into the potential management strategies for this important disease of tomato.
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Affiliation(s)
- Jaw-Rong Chen
- Safe and Sustainable Value Chain, World Vegetable Center, Shanhua, Taiwan
| | - Kevin Aguirre-Carvajal
- Research Center of Information and Communication Technologies, University of A Coruña, A Coruña, Spain
- Bio-Cheminformatics Research Group, Universidad de Las Américas, Quito, Ecuador
| | - Dao-Yuan Xue
- Seed and Seedling Management Section, Taiwan Seed Improvement and Propagation Station, Ministry of Agriculture, Taichung, Taiwan
| | - Hung-Chia Chang
- Safe and Sustainable Value Chain, World Vegetable Center, Shanhua, Taiwan
| | | | - Ya-Ping Lin
- Safe and Sustainable Value Chain, World Vegetable Center, Shanhua, Taiwan
| | - Vinicio Armijos-Jaramillo
- Bio-Cheminformatics Research Group, Universidad de Las Américas, Quito, Ecuador
- Facultad de Ingeniería y Ciencias Aplicadas, Universidad de Las Américas, Quito, Ecuador
| | - Ricardo Oliva
- Safe and Sustainable Value Chain, World Vegetable Center, Shanhua, Taiwan
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4
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Sharma A, Timilsina S, Abrahamian P, Minsavage GV, Jones JB, Vallad GE, Goss EM. Bacterial Mutation During Seasonal Epidemics. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:93-97. [PMID: 38105425 DOI: 10.1094/mpmi-10-23-0164-sc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Rapidly evolving bacterial pathogens pose a unique challenge for long-term plant disease management. In this study, we investigated the types and rate of mutations in bacterial populations during seasonal disease epidemics. Two phylogenetically distinct strains of the bacterial spot pathogen, Xanthomonas perforans, were marked, released in tomato fields, and recaptured at several time points during the growing season. Genomic variations in recaptured isolates were identified by comparative analysis of their whole-genome sequences. In total, 180 unique variations (116 substitutions, 57 insertions/deletions, and 7 structural variations) were identified from 300 genomes, resulting in the overall host-associated mutation rate of ∼0.3 to 0.9/genome/week. This result serves as a benchmark for bacterial mutation during epidemics in similar pathosystems. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Anuj Sharma
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | - Peter Abrahamian
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Gerald V Minsavage
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | - Gary E Vallad
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, U.S.A
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Choudhary M, Minsavage GV, Goss EM, Timilsina S, Coutinho TA, Vallad GE, Paret ML, Jones JB. Whole-Genome-Sequence-Based Classification of Xanthomonas euvesicatoria pv. eucalypti and Computational Analysis of the Type III Secretion System. PHYTOPATHOLOGY 2024; 114:47-60. [PMID: 37505057 DOI: 10.1094/phyto-05-23-0150-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Xanthomonas spp. infect a wide range of annual and perennial plants. Bacterial blight in young seedlings of Eucalyptus spp. in Indonesia was originally identified as X. perforans. However, these strains failed to elicit a hypersensitive response (HR) on either tomatoes or peppers. Two of the strains, EPK43 and BCC 972, when infiltrated into tomato and pepper leaves, failed to grow to significant levels in comparison with well-characterized X. euvesicatoria pv. perforans (Xp) strains. Furthermore, spray inoculation of 'Bonny Best' tomato plants with a bacterial suspension of the Eucalyptus strains resulted in no obvious symptoms. We sequenced the whole genomes of eight strains isolated from two Eucalyptus species between 2007 and 2015. The strains had average nucleotide identities (ANIs) of at least 97.8 with Xp and X. euvesicatoria pv. euvesicatoria (Xeu) strains, both of which are causal agents of bacterial spot of tomatoes and peppers. A comparison of the Eucalyptus strains revealed that the ANI values were >99.99% with each other. Core genome phylogeny clustered all Eucalyptus strains with X. euvesicatoria pv. rosa. They formed separate clades, which included X. euvesicatoria pv. alangii, X. euvesicatoria pv. citrumelonis, and X. euvesicatoria pv. alfalfae. Based on ANI, phylogenetic relationships, and pathogenicity, we designated these Eucalyptus strains as X. euvesicatoria pv. eucalypti (Xee). Comparative analysis of sequenced strains provided unique profiles of type III secretion effectors. Core effector XopD, present in all pathogenic Xp and Xeu strains, was absent in the Xee strains. Comparison of the hrp clusters of Xee, Xp, and Xeu genomes revealed that HrpE in Xee strains was very different from that in Xp and Xeu. To determine if it was functional, we deleted the gene and complemented with the Xee hrpE, confirming it was essential for secretion of type III effectors. HrpE has a hypervariable N-terminus in Xanthomonas spp., in which the N-terminus of Xee strains differs significantly from those of Xeu and Xp strains.
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Affiliation(s)
- Manoj Choudhary
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | - Gerald V Minsavage
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Teresa A Coutinho
- North Florida Research and Education Center, University of Florida, Quincy, FL 32351
| | - Gary E Vallad
- Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomes/Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Mathews L Paret
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
- North Florida Research and Education Center, University of Florida, Quincy, FL 32351
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
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Subedi A, Barrera LBTDL, Ivey ML, Egel DS, Kebede M, Kara S, Aysan Y, Minsavage GV, Roberts PD, Jones JB, Goss EM. Population Genomics Reveals an Emerging Lineage of Xanthomonas perforans on Pepper. PHYTOPATHOLOGY 2024; 114:241-250. [PMID: 37432099 DOI: 10.1094/phyto-04-23-0128-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Xanthomonas perforans-the dominant causal agent of bacterial leaf spot of tomato-is an emerging pathogen of pepper, indicative of a potential host expansion across the southeastern United States. However, studies of the genetic diversity and evolution of X. perforans from pepper remain limited. In this study, the whole-genome sequences of 35 X. perforans strains isolated from pepper from four fields and two transplant facilities across southwest Florida between 2019 and 2021 were used to compare genomic divergence, evolution, and variation in type III secreted effectors. Phylogenetic analysis based on core genes revealed that all 35 X. perforans strains formed one genetic cluster with pepper and tomato strains from Alabama and Turkey and were closely related to strains isolated from tomato in Indiana, Mexico, and Louisiana. The in planta population growth of tomato strains isolated from Indiana, Mexico, Louisiana, and Turkey in pepper leaf mesophyll was on par with pepper X. perforans and X. euvesicatoria strains. Molecular clock analysis of the 35 Florida strains dated their emergence to approximately 2017. While strains varied in copper tolerance, all sequenced strains harbored the avrHah1 transcription activation-like effector located on a conjugative plasmid, not previously reported in Florida. Our findings suggest that there is a geographically distributed lineage of X. perforans strains on tomato that has the genetic background to cause disease on pepper. Moreover, this study clarifies potential adaptive variants of X. perforans on pepper that could help forecast the emergence of such strains and enable immediate or preemptive intervention.
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Affiliation(s)
- Aastha Subedi
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | | | - Melanie Lewis Ivey
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Daniel S Egel
- Botany and Plant Pathology Department, Purdue University, West Lafayette, IN, U.S.A
| | - Misrak Kebede
- Biotechnology Department, Collage of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia
| | - Serhat Kara
- Alata Horticulture Research Institute, Mersin, Turkey
| | - Yesim Aysan
- Department of Plant Protection, Cukurova University, Adana, Turkey
| | - Gerald V Minsavage
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | - Pamela D Roberts
- Southwest Florida Research & Education Center, University of Florida, Immokalee, FL, U.S.A
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL, U.S.A
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, U.S.A
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Kim W, Jeon H, Lee H, Sohn KH, Segonzac C. The Ralstonia pseudosolanacearum Type III Effector RipL Delays Flowering and Promotes Susceptibility to Pseudomonas syringae in Arabidopsis thaliana. Mol Cells 2023; 46:710-724. [PMID: 37968984 PMCID: PMC10654456 DOI: 10.14348/molcells.2023.0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/20/2023] [Accepted: 09/24/2023] [Indexed: 11/17/2023] Open
Abstract
The plant defense responses to microbial infection are tightly regulated and integrated with the developmental program for optimal resources allocation. Notably, the defense- associated hormone salicylic acid (SA) acts as a promoter of flowering while several plant pathogens actively target the flowering signaling pathway to promote their virulence or dissemination. Ralstonia pseudosolanacearum inject tens of effectors in the host cells that collectively promote bacterial proliferation in plant tissues. Here, we characterized the function of the broadly conserved R. pseudosolanacearum effector RipL, through heterologous expression in Arabidopsis thaliana . RipL-expressing transgenic lines presented a delayed flowering, which correlated with a low expression of flowering regulator genes. Delayed flowering was also observed in Nicotiana benthamiana plants transiently expressing RipL. In parallel, RipL promoted plant susceptibility to virulent strains of Pseudomonas syringae in the effector-expressing lines or when delivered by the type III secretion system. Unexpectedly, SA accumulation and SA-dependent immune signaling were not significantly affected by RipL expression. Rather, the RNA-seq analysis of infected RipL-expressing lines revealed that the overall amplitude of the transcriptional response was dampened, suggesting that RipL could promote plant susceptibility in an SA-independent manner. Further elucidation of the molecular mechanisms underpinning RipL effect on flowering and immunity may reveal novel effector functions in host cells.
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Affiliation(s)
- Wanhui Kim
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
| | - Hyelim Jeon
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul 08826, Korea
| | - Hyeonjung Lee
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Kee Hoon Sohn
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Korea
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea
| | - Cécile Segonzac
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea
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8
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Subedi A, Minsavage GV, Jones JB, Goss EM, Roberts PD. Exploring Diversity of Bacterial Spot Associated Xanthomonas Population of Pepper in Southwest Florida. PLANT DISEASE 2023; 107:2978-2985. [PMID: 36856653 DOI: 10.1094/pdis-10-22-2484-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Bacterial spot caused by Xanthomonas spp. is a significant disease that challenges pepper growers worldwide and is particularly severe in a hot and humid environment. Understanding the pathogen's population biology is critical for sustainable disease management. The goal of this study was to characterize the species, race, and bactericide sensitivity of bacterial spot-associated Xanthomonas collected from pepper in Florida. A survey of pepper production fields in southwest Florida between 2019 and 2021-covering two counties, eight farms, and two transplant facilities-resulted in the isolation of 542 Xanthomonas euvesicatoria and 35 Xanthomonas perforans strains. Four races were identified on pepper, of which most strains were race P1 (42%), race P6 (26%), race P3 (24%), and less common was race P4 (8%). All X. perforans strains were characterized as race P1 and showed a compatible reaction on tomato. Sixty-two and 96% of strains were sensitive to copper sulfate and streptomycin, respectively. One farm that did not use copper to manage the disease contained only copper-sensitive strains and was the only farm with race P3 strains. Strains were assayed for starch hydrolysis activity of which a third of X. euvesicatoria strains were strongly amylolytic, a characteristic not typically observed in X. euvesicatoria. All X. perforans strains produced bacteriocins against X. euvesicatoria in vitro. The Xanthomonas population causing bacterial spot on pepper in southwest Florida is diverse and dynamic; thus, regular monitoring provides pertinent information to plant breeders and growers for designing disease management strategies.
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Affiliation(s)
- Aastha Subedi
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | | | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL
- Emerging Pathogens Institute, University of Florida, Gainesville, FL
| | - Pamela D Roberts
- Southwest Florida Research and Education Center, University of Florida, Immokalee, FL
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Ahn YJ, Kim H, Choi S, Mazo-Molina C, Prokchorchik M, Zhang N, Kim B, Mang H, Koehler N, Kim J, Lee S, Yoon H, Choi D, Kim MS, Segonzac C, Martin GB, Schultink A, Sohn KH. Ptr1 and ZAR1 immune receptors confer overlapping and distinct bacterial pathogen effector specificities. THE NEW PHYTOLOGIST 2023; 239:1935-1953. [PMID: 37334551 DOI: 10.1111/nph.19073] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 05/22/2023] [Indexed: 06/20/2023]
Abstract
Some nucleotide-binding and leucine-rich repeat receptors (NLRs) indirectly detect pathogen effectors by monitoring their host targets. In Arabidopsis thaliana, RIN4 is targeted by multiple sequence-unrelated effectors and activates immune responses mediated by RPM1 and RPS2. These effectors trigger cell death in Nicotiana benthamiana, but the corresponding NLRs have yet not been identified. To identify N. benthamiana NLRs (NbNLRs) that recognize Arabidopsis RIN4-targeting effectors, we conducted a rapid reverse genetic screen using an NbNLR VIGS library. We identified that the N. benthamiana homolog of Ptr1 (Pseudomonas tomato race 1) recognizes the Pseudomonas effectors AvrRpt2, AvrRpm1, and AvrB. We demonstrated that recognition of the Xanthomonas effector AvrBsT and the Pseudomonas effector HopZ5 is conferred independently by the N. benthamiana homolog of Ptr1 and ZAR1. Interestingly, the recognition of HopZ5 and AvrBsT is contributed unequally by Ptr1 and ZAR1 in N. benthamiana and Capsicum annuum. In addition, we showed that the RLCK XII family protein JIM2 is required for the NbZAR1-dependent recognition of AvrBsT and HopZ5. The recognition of sequence-unrelated effectors by NbPtr1 and NbZAR1 provides an additional example of convergently evolved effector recognition. Identification of key components involved in Ptr1 and ZAR1-mediated immunity could reveal unique mechanisms of expanded effector recognition.
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Affiliation(s)
- Ye Jin Ahn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Haseong Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
| | - Sera Choi
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Carolina Mazo-Molina
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Maxim Prokchorchik
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Ning Zhang
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Boyoung Kim
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Korea
| | - Hyunggon Mang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Naio Koehler
- Fortiphyte Inc., 3071 Research Drive, Richmond, CA, 94806, USA
| | - Jieun Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Soeui Lee
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Korea
| | - Hayeon Yoon
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Doil Choi
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Korea
| | - Min-Sung Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Cécile Segonzac
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Korea
| | - Gregory B Martin
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Alex Schultink
- Fortiphyte Inc., 3071 Research Drive, Richmond, CA, 94806, USA
| | - Kee Hoon Sohn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Korea
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Korea
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10
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Bibi S, Weis K, Kaur A, Bhandari R, Goss E, Jones JB, Potnis N. A Brief Evaluation of a Copper Resistance Mobile Genetic Island in the Bacterial Leaf Spot Pathogen Xanthomonas euvesicatoria pv. perforans. PHYTOPATHOLOGY 2023; 113:1394-1398. [PMID: 37097444 DOI: 10.1094/phyto-02-23-0077-sc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Due to the continuous use of copper containing bactericides without effective alternative bactericides, copper resistance has become more prevalent in plant pathogens, including Xanthomonas euvesicatoria pv. perforans (formerly Xanthomonas perforans), a predominant cause of bacterial leaf spot disease of tomato and pepper in the Southeastern United States. Previously, reports of copper resistance have been associated with a large conjugative plasmid. However, we have characterized a copper resistance genomic island located within the chromosome of multiple X. euvesicatoria pv. perforans strains. The island is distinct from a previously described chromosomally encoded copper resistance island in X. vesicatoria strain XVP26. Computational analysis revealed the genomic island to contain multiple genes associated with genetic mobility, including both phage-related genes and transposase. Among copper-tolerant strains of X. euvesicatoria pv. perforans isolated from Florida, the majority of strains were found to have the copper resistance chromosomally encoded rather than plasmid borne. Our results suggest that this copper resistance island may have two modes of horizontal gene transfer and that chromosomally encoded copper resistance genes may provide a fitness advantage over plasmid-borne resistance.
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Affiliation(s)
- Shaheen Bibi
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Kylie Weis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Amandeep Kaur
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Rishi Bhandari
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Erica Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
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11
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Kim H, Ahn YJ, Lee H, Chung EH, Segonzac C, Sohn KH. Diversified host target families mediate convergently evolved effector recognition across plant species. CURRENT OPINION IN PLANT BIOLOGY 2023; 74:102398. [PMID: 37295296 DOI: 10.1016/j.pbi.2023.102398] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/13/2023] [Accepted: 05/15/2023] [Indexed: 06/12/2023]
Abstract
Recognition of pathogen effectors is a crucial step for triggering plant immunity. Resistance (R) genes often encode for nucleotide-binding leucine-rich repeat receptors (NLRs), and NLRs detect effectors from pathogens to trigger effector-triggered immunity (ETI). NLR recognition of effectors is observed in diverse forms where NLRs directly interact with effectors or indirectly detect effectors by monitoring host guardees/decoys (HGDs). HGDs undergo different biochemical modifications by diverse effectors and expand the effector recognition spectrum of NLRs, contributing robustness to plant immunity. Interestingly, in many cases of the indirect recognition of effectors, HGD families targeted by effectors are conserved across the plant species while NLRs are not. Notably, a family of diversified HGDs can activate multiple non-orthologous NLRs across plant species. Further investigation on HGDs would reveal the mechanistic basis of how the diversification of HGDs confers novel effector recognition by NLRs.
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Affiliation(s)
- Haseong Kim
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Ye Jin Ahn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Hyeonjung Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Eui-Hwan Chung
- Department of Plant Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Cécile Segonzac
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Republic of Korea; Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea; Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, Republic of Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Kee Hoon Sohn
- Plant Immunity Research Center, Seoul National University, Seoul, 08826, Republic of Korea; Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, Republic of Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea; Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Republic of Korea.
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12
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Bianco MI, Ponso MA, Garita-Cambronero J, Conforte VP, Galván TE, Dunger G, Morales GM, Vojnov AA, Romero AM, Cubero J, Yaryura PM. Genomic and phenotypic insight into Xanthomonas vesicatoria strains with different aggressiveness on tomato. Front Microbiol 2023; 14:1185368. [PMID: 37440880 PMCID: PMC10333488 DOI: 10.3389/fmicb.2023.1185368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 06/09/2023] [Indexed: 07/15/2023] Open
Abstract
Xanthomonas vesicatoria is one of the causal agents of bacterial spot, a disease that seriously affects the production of tomato (Solanum lycopersicum) and pepper (Capsicum annum) worldwide. In Argentina, bacterial spot is found in all tomato producing areas, with X. vesicatoria being one of the main species detected in the fields. Previously, we isolated three X. vesicatoria strains BNM 208, BNM 214, and BNM 216 from tomato plants with bacterial spot, and found they differed in their ability to form biofilm and in their degree of aggressiveness. Here, the likely causes of those differences were explored through genotypic and phenotypic studies. The genomes of the three strains were sequenced and assembled, and then compared with each other and also with 12 other publicly available X. vesicatoria genomes. Phenotypic characteristics (mainly linked to biofilm formation and virulence) were studied in vitro. Our results show that the differences observed earlier between BNM 208, BNM 214, and BNM 216 may be related to the structural characteristics of the xanthan gum produced by each strain, their repertoire of type III effectors (T3Es), the presence of certain genes associated with c-di-GMP metabolism and type IV pili (T4P). These findings on the pathogenicity mechanisms of X. vesicatoria could be useful for developing bacterial spot control strategies aimed at interfering with the infection processes.
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Affiliation(s)
- María Isabel Bianco
- Instituto de Ciencia y Tecnología Dr. César Milstein – Fundación Pablo Cassará – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Instituto de Investigación en Medicina y Ciencias de la Salud, Facultad de Medicina, Universidad del Salvador, Buenos Aires, Argentina
| | - María Agustina Ponso
- Instituto Multidisciplinario de Investigación y Transferencia Agroalimentario y Biotecnológica (IMITAB, UNVM-CONICET), Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas, Universidad Nacional de Villa María, Villa María, Argentina
| | | | - Valeria Paola Conforte
- Instituto de Ciencia y Tecnología Dr. César Milstein – Fundación Pablo Cassará – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Instituto de Investigación en Medicina y Ciencias de la Salud, Facultad de Medicina, Universidad del Salvador, Buenos Aires, Argentina
| | - Tadeo E. Galván
- Instituto de Ciencia y Tecnología Dr. César Milstein – Fundación Pablo Cassará – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Germán Dunger
- Facultad de Ciencias Agrarias, Instituto de Ciencias Agropecuarias del Litoral, CONICET, Universidad Nacional del Litoral, Esperanza, Argentina
| | - Gustavo M. Morales
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados, Universidad Nacional de Rio Cuarto – CONICET, Rio Cuarto, Argentina
| | - Adrián Alberto Vojnov
- Instituto de Ciencia y Tecnología Dr. César Milstein – Fundación Pablo Cassará – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Instituto de Investigación en Medicina y Ciencias de la Salud, Facultad de Medicina, Universidad del Salvador, Buenos Aires, Argentina
| | - Ana María Romero
- Cátedra de Fitopatología, Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jaime Cubero
- Laboratorio de Bacteriología, Departamento de Protección Vegetal, Instituto Nacional de Investigación y Tecnología Agraria/Consejo Superior de Investigaciones Científicas (INIA/CSIC), Madrid, Spain
| | - Pablo Marcelo Yaryura
- Instituto Multidisciplinario de Investigación y Transferencia Agroalimentario y Biotecnológica (IMITAB, UNVM-CONICET), Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas, Universidad Nacional de Villa María, Villa María, Argentina
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13
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Teper D, White FF, Wang N. The Dynamic Transcription Activator-Like Effector Family of Xanthomonas. PHYTOPATHOLOGY 2023; 113:651-666. [PMID: 36449529 DOI: 10.1094/phyto-10-22-0365-kd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Transcription activator-like effectors (TALEs) are bacterial proteins that are injected into the eukaryotic nucleus to act as transcriptional factors and function as key virulence factors of the phytopathogen Xanthomonas. TALEs are translocated into plant host cells via the type III secretion system and induce the expression of host susceptibility (S) genes to facilitate disease. The unique modular DNA binding domains of TALEs comprise an array of nearly identical direct repeats that enable binding to DNA targets based on the recognition of a single nucleotide target per repeat. The very nature of TALE structure and function permits the proliferation of TALE genes and evolutionary adaptations in the host to counter TALE function, making the TALE-host interaction the most dynamic story in effector biology. The TALE genes appear to be a relatively young effector gene family, with a presence in all virulent members of some species and absent in others. Genome sequencing has revealed many TALE genes throughout the xanthomonads, and relatively few have been associated with a cognate S gene. Several species, including Xanthomonas oryzae pv. oryzae and X. citri pv. citri, have near absolute requirement for TALE gene function, while the genes appear to be just now entering the disease interactions with new fitness contributions to the pathogens of tomato and pepper among others. Deciphering the simple and effective DNA binding mechanism also has led to the development of DNA manipulation tools in fields of gene editing and transgenic research. In the three decades since their discovery, TALE research remains at the forefront of the study of bacterial evolution, plant-pathogen interactions, and synthetic biology. We also discuss critical questions that remain to be addressed regarding TALEs.
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Affiliation(s)
- Doron Teper
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Rishon LeZion, Israel
| | - Frank F White
- Department of Plant Pathology, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville, FL, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, FL, U.S.A
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14
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Newberry EA, Minsavage GV, Holland A, Jones JB, Potnis N. Genome-Wide Association to Study the Host-Specificity Determinants of Xanthomonas perforans. PHYTOPATHOLOGY 2023; 113:400-412. [PMID: 36318253 DOI: 10.1094/phyto-08-22-0294-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Xanthomonas perforans and X. euvesicatoria are the causal agents of bacterial spot disease of tomato and pepper, endemic to the Southeastern United States. Although very closely related, the two bacterial species differ in host specificity, where X. perforans is the dominant pathogen of tomato and X. euvesicatoria that of pepper. This is in part due to the activity of avirulence proteins that are secreted by X. perforans strains and elicit effector-triggered immunity in pepper leaves, thereby restricting pathogen growth. In recent years, the emergence of several pepper-pathogenic X. perforans lineages has revealed variability within the bacterial species to multiply and cause disease in pepper, even in the absence of avirulence gene activity. Here, we investigated the basal evolutionary processes underlying the host range of this species using multiple genome-wide association analyses. Surprisingly, we identified two novel gene candidates that were significantly associated with pepper-pathogenic X. perforans and X. euvesicatoria. Both candidates were predicted to be involved in the transport/acquisition of nutrients common to the plant cell wall or apoplast and included a TonB-dependent receptor, which was disrupted through independent mutations within the X. perforans lineage. The other included a symporter of protons/glutamate, gltP, enriched with pepper-associated mutations near the promoter and start codon of the gene. Functional analysis of these candidates revealed that only the TonB-dependent receptor had a minor effect on the symptom development and growth of X. perforans in pepper leaves, indicating that pathogenicity to this host might have evolved independently within the bacterial species and is likely a complex, multigenic trait.
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Affiliation(s)
- Eric A Newberry
- Department of Entomology and Plant Pathology, Auburn University, AL 36849
| | | | - Auston Holland
- Department of Entomology and Plant Pathology, Auburn University, AL 36849
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, FL 32611
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, AL 36849
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15
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De Ryck J, Van Damme P, Goormachtig S. From prediction to function: Current practices and challenges towards the functional characterization of type III effectors. Front Microbiol 2023; 14:1113442. [PMID: 36846751 PMCID: PMC9945535 DOI: 10.3389/fmicb.2023.1113442] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/19/2023] [Indexed: 02/10/2023] Open
Abstract
The type III secretion system (T3SS) is a well-studied pathogenicity determinant of many bacteria through which effectors (T3Es) are translocated into the host cell, where they exercise a wide range of functions to deceive the host cell's immunity and to establish a niche. Here we look at the different approaches that are used to functionally characterize a T3E. Such approaches include host localization studies, virulence screenings, biochemical activity assays, and large-scale omics, such as transcriptomics, interactomics, and metabolomics, among others. By means of the phytopathogenic Ralstonia solanacearum species complex (RSSC) as a case study, the current advances of these methods will be explored, alongside the progress made in understanding effector biology. Data obtained by such complementary methods provide crucial information to comprehend the entire function of the effectome and will eventually lead to a better understanding of the phytopathogen, opening opportunities to tackle it.
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Affiliation(s)
- Joren De Ryck
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium,Center for Plant Systems Biology, VIB, Ghent, Belgium,iRIP Unit, Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Petra Van Damme
- iRIP Unit, Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Sofie Goormachtig
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium,Center for Plant Systems Biology, VIB, Ghent, Belgium,*Correspondence: Sofie Goormachtig,
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16
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Klein-Gordon JM, Guingab-Cagmat J, Minsavage GV, Meke L, Vallad GE, Goss EM, Garrett TJ, Jones JB. Strength in Numbers: Density-Dependent Volatile-Induced Antimicrobial Activity by Xanthomonas perforans. PHYTOPATHOLOGY 2023; 113:160-169. [PMID: 36129764 DOI: 10.1094/phyto-04-22-0131-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
For most of the 20th century, Xanthomonas euvesicatoria was the only known bacterium associated with bacterial spot of tomato in Florida. X. perforans quickly replaced X. euvesicatoria, mainly because of production of three bacteriocins (BCNs) against X. euvesicatoria; however, X. perforans outcompeted X. euvesicatoria even when the three known BCNs were deleted. Surprisingly, we observed antimicrobial activity against X. euvesicatoria in the BCN triple mutant when the triple mutant was grown in Petri plates containing multiple spots but not in Petri plates containing only one spot. We determined that changes in the headspace composition (i.e., volatiles) rather than a diffusible signal in the agar were required for induction of the antimicrobial activity. Other Xanthomonas species also produced volatile-induced antimicrobial compounds against X. euvesicatoria and elicited antimicrobial activity by X. perforans. A wide range of plant pathogenic bacteria, including Clavibacter michiganensis subsp. michiganensis, Pantoea stewartii, and Pseudomonas cichorii, also elicited antimicrobial activity by X. perforans when multiple spots of the species were present. To identify potential antimicrobial compounds, we performed liquid chromatography with high-resolution mass spectrometry of the agar surrounding the spot in the high cell density Petri plates where the antimicrobial activity was present compared with agar surrounding the spot in Petri plates with one spot where antimicrobial activity was not observed. Among the compounds identified in the zone of inhibition were N-butanoyl-L-homoserine lactone and N-(3-hydroxy-butanoyl)-homoserine lactone, which are known quorum-sensing metabolites in other bacteria.
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Affiliation(s)
- Jeannie M Klein-Gordon
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI
| | - Joy Guingab-Cagmat
- Southeast Center for Integrated Metabolomics (SECIM), University of Florida, Gainesville, FL
| | - Gerald V Minsavage
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL
| | - Laurel Meke
- Southeast Center for Integrated Metabolomics (SECIM), University of Florida, Gainesville, FL
| | - Gary E Vallad
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL
- Gulf Coast Research and Education Center, IFAS, University of Florida, Balm, FL
| | - Erica M Goss
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL
- Emerging Pathogens Institute, University of Florida, Gainesville, FL
| | - Timothy J Garrett
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Jeffrey B Jones
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL
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17
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Xanthomonas
Infection Transforms the Apoplast into an Accessible and Habitable Niche for Salmonella enterica. Appl Environ Microbiol 2022; 88:e0133022. [PMID: 36314834 PMCID: PMC9680631 DOI: 10.1128/aem.01330-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial spot disease caused by
Xanthomonas
species devastates tomato production worldwide. Salmonellosis outbreaks from consumption of raw produce have been linked to the arrival of
Salmonella enterica
on crop plants in the field via contaminated irrigation water.
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18
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A Pan-Global Study of Bacterial Leaf Spot of Chilli Caused by Xanthomonas spp. PLANTS 2022; 11:plants11172291. [PMID: 36079673 PMCID: PMC9460788 DOI: 10.3390/plants11172291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/22/2022] [Accepted: 08/26/2022] [Indexed: 11/17/2022]
Abstract
Bacterial Leaf Spot (BLS) is a serious bacterial disease of chilli (Capsicum spp.) caused by at least four different Xanthomonas biotypes: X. euvesicatoria pv. euvesicatoria, X. euvesicatoria pv. perforans, X. hortorum pv. gardneri, and X. vesicatoria. Symptoms include black lesions and yellow halos on the leaves and fruits, resulting in reports of up to 66% losses due to unsalable and damaged fruits. BLS pathogens are widely distributed in tropical and subtropical regions. Xanthomonas is able to survive in seeds and crop residues for short periods, leading to the infections in subsequent crops. The pathogen can be detected using several techniques, but largely via a combination of traditional and molecular approaches. Conventional detection is based on microscopic and culture observations, while a suite of Polymerase Chain Reaction (PCR) and Loop-Mediated Isothermal Amplification (LAMP) assays are available. Management of BLS is challenging due to the broad genetic diversity of the pathogens, a lack of resilient host resistance, and poor efficacy of chemical control. Some biological control agents have been reported, including bacteriophage deployment. Incorporating stable host resistance is a critical component in ongoing integrated management for BLS. This paper reviews the current status of BLS of chilli, including its distribution, pathogen profiles, diagnostic options, disease management, and the pursuit of plant resistance.
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19
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Wang H, Wagnon R, Moreno D, Timilsina S, Jones J, Vallad G, Turechek WW. A Long-Amplicon Viability-qPCR Test for Quantifying Living Pathogens that Cause Bacterial Spot in Tomato Seed. PLANT DISEASE 2022; 106:1474-1485. [PMID: 34894749 DOI: 10.1094/pdis-11-21-2509-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Bacterial spot is one of the most serious diseases of tomato. It is caused by four species of Xanthomonas: X. euvesicatoria, X. gardneri, X. perforans, and X. vesicatoria. Contaminated or infected seed can be a major source of inoculum for this disease. The use of certified pathogen-free seed is one of the primary management practices to reduce the inoculum load in commercial production. Current seed testing protocols rely mainly on plating the seed extract and conventional PCR; however, the plating method cannot detect viable but nonculturable cells, and the conventional PCR assay has limited capability to differentiate DNA extracted from viable or dead bacterial cells. To improve the sensitivity and specificity of the tomato seed testing method for bacterial spot pathogens, a long-amplicon quantitative PCR (qPCR) assay coupled with propidium monoazide (PMA-qPCR) was developed to quantify selectively the four pathogenic Xanthomonas species in tomato seed. The optimized PMA-qPCR procedure was evaluated on pure bacterial suspensions, bacteria-spiked seed extracts, and seed extracts of inoculated and naturally infected seed. A crude DNA extraction protocol also was developed, and PMA-qPCR with crude bacterial DNA extracts resulted in accurate quantification of 104 to 108 CFU/ml of viable bacteria when mixed with dead cells at concentrations as high as 107 CFU/ml in the seed extracts. With DNA purified from concentrated seed extracts, the PMA-qPCR assay was able to detect DNA of the target pathogens in seed samples spiked with ≥75 CFU/ml (about 0.5 CFU/seed) of the viable pathogens. Latent class analysis of the inoculated and naturally infected seed samples showed that the PMA-qPCR assay had greater sensitivity than plating the seed extracts on the semiselective modified Tween Medium B and CKTM media for all four target species. Being much faster and more sensitive than dilution plating, the PMA-qPCR assay has potential to be used as a standalone tool or in combination with the plating method to improve tomato seed testing and advance the production of clean seed.
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Affiliation(s)
- Hehe Wang
- EDISTO Research and Education Center, Clemson University, Blackville, SC 29817
| | - Rieanna Wagnon
- EDISTO Research and Education Center, Clemson University, Blackville, SC 29817
| | - Daniela Moreno
- EDISTO Research and Education Center, Clemson University, Blackville, SC 29817
| | | | | | - Gary Vallad
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
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20
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Dia NC, Morinière L, Cottyn B, Bernal E, Jacobs J, Koebnik R, Osdaghi E, Potnis N, Pothier J. Xanthomonas hortorum - beyond gardens: Current taxonomy, genomics, and virulence repertoires. MOLECULAR PLANT PATHOLOGY 2022; 23:597-621. [PMID: 35068051 PMCID: PMC8995068 DOI: 10.1111/mpp.13185] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 05/02/2023]
Abstract
TAXONOMY Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Lysobacterales (earlier synonym of Xanthomonadales); Family Lysobacteraceae (earlier synonym of Xanthomonadaceae); Genus Xanthomonas; Species X. hortorum; Pathovars: pv. carotae, pv. vitians, pv. hederae, pv. pelargonii, pv. taraxaci, pv. cynarae, and pv. gardneri. HOST RANGE Xanthomonas hortorum affects agricultural crops, and horticultural and wild plants. Tomato, carrot, artichoke, lettuce, pelargonium, ivy, and dandelion were originally described as the main natural hosts of the seven separate pathovars. Artificial inoculation experiments also revealed other hosts. The natural and experimental host ranges are expected to be broader than initially assumed. Additionally, several strains, yet to be assigned to a pathovar within X. hortorum, cause diseases on several other plant species such as peony, sweet wormwood, lavender, and oak-leaf hydrangea. EPIDEMIOLOGY AND CONTROL X. hortorum pathovars are mainly disseminated by infected seeds (e.g., X. hortorum pvs carotae and vitians) or cuttings (e.g., X. hortorum pv. pelargonii) and can be further dispersed by wind and rain, or mechanically transferred during planting and cultivation. Global trade of plants, seeds, and other propagating material constitutes a major pathway for their introduction and spread into new geographical areas. The propagules of some pathovars (e.g., X. horturum pv. pelargonii) are spread by insect vectors, while those of others can survive in crop residues and soils, and overwinter until the following growing season (e.g., X. hortorum pvs vitians and carotae). Control measures against X. hortorum pathovars are varied and include exclusion strategies (i.e., by using certification programmes and quarantine regulations) to multiple agricultural practices such as the application of phytosanitary products. Copper-based compounds against X. hortorum are used, but the emergence of copper-tolerant strains represents a major threat for their effective management. With the current lack of efficient chemical or biological disease management strategies, host resistance appears promising, but is not without challenges. The intrastrain genetic variability within the same pathovar poses a challenge for breeding cultivars with durable resistance. USEFUL WEBSITES https://gd.eppo.int/taxon/XANTGA, https://gd.eppo.int/taxon/XANTCR, https://gd.eppo.int/taxon/XANTPE, https://www.euroxanth.eu, http://www.xanthomonas.org, http://www.xanthomonas.org/dokuwiki.
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Affiliation(s)
- Nay C. Dia
- Environmental Genomics and Systems Biology Research GroupInstitute for Natural Resource SciencesZurich University of Applied SciencesWädenswilSwitzerland
- Molecular Plant BreedingInstitute of Agricultural SciencesETH ZurichZurichSwitzerland
| | - Lucas Morinière
- University of LyonUniversité Claude Bernard Lyon 1CNRSINRAEUMR Ecologie MicrobienneVilleurbanneFrance
| | - Bart Cottyn
- Plant Sciences UnitFlanders Research Institute for Agriculture, Fisheries and FoodMerelbekeBelgium
| | - Eduardo Bernal
- Department of Plant PathologyThe Ohio State UniversityColumbusOhioUSA
| | - Jonathan M. Jacobs
- Department of Plant PathologyThe Ohio State UniversityColumbusOhioUSA
- Infectious Diseases InstituteThe Ohio State UniversityColumbusOhioUSA
| | - Ralf Koebnik
- Plant Health Institute of MontpellierUniversity of Montpellier, CIRAD, INRAe, Institut Agro, IRDMontpellierFrance
| | - Ebrahim Osdaghi
- Department of Plant ProtectionCollege of AgricultureUniversity of TehranKarajIran
| | - Neha Potnis
- Department of Entomology and Plant PathologyAuburn UniversityAlabamaUSA
| | - Joël F. Pothier
- Environmental Genomics and Systems Biology Research GroupInstitute for Natural Resource SciencesZurich University of Applied SciencesWädenswilSwitzerland
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21
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Raffeiner M, Üstün S, Guerra T, Spinti D, Fitzner M, Sonnewald S, Baldermann S, Börnke F. The Xanthomonas type-III effector XopS stabilizes CaWRKY40a to regulate defense responses and stomatal immunity in pepper (Capsicum annuum). THE PLANT CELL 2022; 34:1684-1708. [PMID: 35134217 PMCID: PMC9048924 DOI: 10.1093/plcell/koac032] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/20/2022] [Indexed: 05/26/2023]
Abstract
As a critical part of plant immunity, cells that are attacked by pathogens undergo rapid transcriptional reprogramming to minimize virulence. Many bacterial phytopathogens use type III effector (T3E) proteins to interfere with plant defense responses, including this transcriptional reprogramming. Here, we show that Xanthomonas outer protein S (XopS), a T3E of Xanthomonas campestris pv. vesicatoria (Xcv), interacts with and inhibits proteasomal degradation of WRKY40, a transcriptional regulator of defense gene expression. Virus-induced gene silencing of WRKY40 in pepper (Capsicum annuum) enhanced plant tolerance to Xcv infection, indicating that WRKY40 represses immunity. Stabilization of WRKY40 by XopS reduces the expression of its targets, which include salicylic acid-responsive genes and the jasmonic acid signaling repressor JAZ8. Xcv bacteria lacking XopS display significantly reduced virulence when surface inoculated onto susceptible pepper leaves. XopS delivery by Xcv, as well as ectopic expression of XopS in Arabidopsis thaliana or Nicotiana benthamiana, prevented stomatal closure in response to bacteria and biotic elicitors. Silencing WRKY40 in pepper or N. benthamiana abolished XopS's ability to prevent stomatal closure. This suggests that XopS interferes with both preinvasion and apoplastic defense by manipulating WRKY40 stability and downstream gene expression, eventually altering phytohormone crosstalk to promote pathogen proliferation.
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Affiliation(s)
- Margot Raffeiner
- Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren 14979, Germany
| | | | - Tiziana Guerra
- Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren 14979, Germany
| | - Daniela Spinti
- Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren 14979, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam 14476, Germany
| | - Maria Fitzner
- Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren 14979, Germany
| | - Sophia Sonnewald
- Department of Biology, Division of Biochemistry, Friedrich-Alexander-Universität, Erlangen 91058, Germany
| | - Susanne Baldermann
- Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren 14979, Germany
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Nuthetal 14558, Germany
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22
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Jibrin MO, Timilsina S, Minsavage GV, Vallad GE, Roberts PD, Goss EM, Jones JB. Bacterial Spot of Tomato and Pepper in Africa: Diversity, Emergence of T5 Race, and Management. Front Microbiol 2022; 13:835647. [PMID: 35509307 PMCID: PMC9058171 DOI: 10.3389/fmicb.2022.835647] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/21/2022] [Indexed: 11/13/2022] Open
Abstract
Bacterial spot disease was first reported from South Africa by Ethel M. Doidge in 1920. In the ensuing century after the initial discovery, the pathogen has gained global attention in plant pathology research, providing insights into host-pathogen interactions, pathogen evolution, and effector discovery, such as the first discovery of transcription activation-like effectors, among many others. Four distinct genetic groups, including Xanthomonas euvesicatoria (proposed name: X. euvesicatoria pv. euvesicatoria), Xanthomonas perforans (proposed name: X. euvesicatoria pv. perforans), Xanthomonas gardneri (proposed name: Xanthomonas hortorum pv. gardneri), and Xanthomonas vesicatoria, are known to cause bacterial spot disease. Recently, a new race of a bacterial spot pathogen, race T5, which is a product of recombination between at least two Xanthomonas species, was reported in Nigeria. In this review, our focus is on the progress made on the African continent, vis-à-vis progress made in the global bacterial spot research community to provide a body of information useful for researchers in understanding the diversity, evolutionary changes, and management of the disease in Africa.
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Affiliation(s)
- Mustafa Ojonuba Jibrin
- Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA, United States
- Department of Crop Protection, Ahmadu Bello University, Zaria, Nigeria
| | - Sujan Timilsina
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
| | - Gerald V. Minsavage
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
| | - Garry E. Vallad
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States
| | - Pamela D. Roberts
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
- UF/IFAS Southwest Florida Research and Education Center, Immokalee, FL, United States
| | - Erica M. Goss
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Jeffrey B. Jones
- Plant Pathology Department, University of Florida, Gainesville, FL, United States
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23
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Bernal E, Rotondo F, Roman-Reyna V, Klass T, Timilsina S, Minsavage GV, Iruegas-Bocardo F, Goss EM, Jones JB, Jacobs JM, Miller SA, Francis DM. Migration Drives the Replacement of Xanthomonas perforans Races in the Absence of Widely Deployed Resistance. Front Microbiol 2022; 13:826386. [PMID: 35369455 PMCID: PMC8971904 DOI: 10.3389/fmicb.2022.826386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/09/2022] [Indexed: 11/13/2022] Open
Abstract
Changes in Xanthomonas race and species composition causing bacterial spot of tomato have occurred throughout the world and are often associated with epidemics. Knowledge of bacterial population structure is key for resistance discovery and deployment. We surveyed Xanthomonas spp. composition from processing tomato fields in the Midwestern United States over a 4-year period between 2017 and 2020, compared these to strains collected previously, and found that X. perforans is currently the most prevalent species. We characterized 564 X. perforans isolates for sequence variation in avrXv3 to distinguish between race T3 and T4 and validated race designation using hypersensitive response (HR) assays for 106 isolates. Race T4 accounted for over 95% of X. perforans isolates collected in the Midwest between 2017 and 2020. Whole genome sequencing, Average Nucleotide Identity (ANI) analysis, core genome alignment and single nucleotide polymorphism (SNP) detection relative to a reference strain, and phylogenomic analysis suggest that the majority of Midwestern X. perforans strains collected between 2017 and 2020 were nearly identical, with greater than 99.99% ANI to X. perforans isolates collected from Collier County, Florida in 2012. These isolates shared a common SNP variant resulting an a premature stop codon in avrXv3. One sequenced isolate was identified with a deletion of avrXv3 and shared 99.99% ANI with a strain collected in Collier Co., Florida in 2006. A population shift to X. perforans T4 occurred in the absence of widely deployed resistance, with only 7% of tomato varieties tested having the resistant allele at the Xv3/Rx-4 locus. The persistence of nearly identical strains over multiple years suggests that migration led to the establishment of an endemic population. Our findings validate a genomics-based framework to track shifts in X. perforans populations due to migration, mutation, drift, or selection based on comparisons to 146 genomes.
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Affiliation(s)
- Eduardo Bernal
- Department of Horticulture and Crop Science, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Francesca Rotondo
- Department of Plant Pathology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Veronica Roman-Reyna
- Department of Plant Pathology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH, United States
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, United States
| | - Taylor Klass
- Department of Plant Pathology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH, United States
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, United States
| | - Sujan Timilsina
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
| | - Gerald V. Minsavage
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
| | - Fernanda Iruegas-Bocardo
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
| | - Erica M. Goss
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Jeffrey B. Jones
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
| | - Jonathan M. Jacobs
- Department of Plant Pathology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH, United States
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, United States
| | - Sally A. Miller
- Department of Plant Pathology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - David M. Francis
- Department of Horticulture and Crop Science, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Wooster, OH, United States
- *Correspondence: David M. Francis,
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24
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Fan Q, Bibi S, Vallad GE, Goss EM, Hurlbert JC, Paret ML, Jones JB, Timilsina S. Identification of Genes in Xanthomonas euvesicatoria pv. rosa That Are Host Limiting in Tomato. PLANTS 2022; 11:plants11060796. [PMID: 35336678 PMCID: PMC8951399 DOI: 10.3390/plants11060796] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/24/2022] [Accepted: 03/02/2022] [Indexed: 11/30/2022]
Abstract
Xanthomonas euvesicatoria pv. rosa strain Xer07 causes a leaf spot on a Rosa sp. and is closely related to X. euvesicatoria pv. euvesicatoria (Xee) and X. perforans (Xp), causal agents of bacterial spot of tomato. However, Xer07 is not pathogenic on tomato and elicits a hypersensitive reaction (HR). We compared the genomes of the three bacterial species to identify the factors that limit Xer07 on tomato. Comparison of pathogenicity associated factors including the type III secretion systems identified two genes, xopA and xer3856, in Xer07 that have lower sequence homology in tomato pathogens. xer3856 is a homolog of genes in X. citri (xac3856) and X. fuscans pv. aurantifolii, both of which have been reported to elicit HRs in tomato. When xer3856 was expressed in X. perforans and infiltrated in tomato leaflets, the transconjugant elicited an HR and significantly reduced bacterial populations compared to the wildtype X. perforans strain. When xer3856 was mutated in Xer07, the mutant strain still triggered an HR in tomato leaflets. The second gene identified codes for type III secreted effector XopA, which contains a harpin domain that is distinct from the xopA homologs in Xee and Xp. The Xer07-xopA, when expressed in X. perforans, did not elicit an HR in tomato leaflets, but significantly reduced bacterial populations. This indicates that xopA and xer3856 genes in combination with an additional factor(s) limit Xer07 in tomato.
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Affiliation(s)
- Qiurong Fan
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
| | - Shaheen Bibi
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
| | - Gary E. Vallad
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
- Gulf Coast Research and Education Center, University of Florida, Balm, FL 33598, USA
| | - Erica M. Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA
| | - Jason C. Hurlbert
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC 29733, USA;
| | - Matthews L. Paret
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
- North Florida Research and Education Center, University of Florida, Quincy, FL 32351, USA
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
- Correspondence: (J.B.J.); (S.T.)
| | - Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (Q.F.); (S.B.); (G.E.V.); (E.M.G.); (M.L.P.)
- Correspondence: (J.B.J.); (S.T.)
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25
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Jain M, Cai L, Black I, Azadi P, Carlson RW, Jones KM, Gabriel DW. ' Candidatus Liberibacter asiaticus'-Encoded BCP Peroxiredoxin Suppresses Lipopolysaccharide-Mediated Defense Signaling and Nitrosative Stress In Planta. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:257-273. [PMID: 34931906 DOI: 10.1094/mpmi-09-21-0230-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The lipopolysaccharides (LPS) of gram-negative bacteria trigger a nitrosative and oxidative burst in both animals and plants during pathogen invasion. Liberibacter crescens strain BT-1 is a surrogate for functional genomic studies of the uncultured pathogenic 'Candidatus Liberibacter' spp. that are associated with severe diseases such as citrus greening and potato zebra chip. Structural determination of L. crescens LPS revealed the presence of a very long chain fatty acid modification. L. crescens LPS pretreatment suppressed growth of Xanthomonas perforans on nonhost tobacco (Nicotiana benthamiana) and X. citri subsp. citri on host orange (Citrus sinensis), confirming bioactivity of L. crescens LPS in activation of systemic acquired resistance (SAR). L. crescens LPS elicited a rapid burst of nitric oxide (NO) in suspension cultured tobacco cells. Pharmacological inhibitor assays confirmed that arginine-utilizing NO synthase (NOS) activity was the primary source of NO generation elicited by L. crescens LPS. LPS treatment also resulted in biological markers of NO-mediated SAR activation, including an increase in the glutathione pool, callose deposition, and activation of the salicylic acid and azelaic acid (AzA) signaling networks. Transient expression of 'Ca. L. asiaticus' bacterioferritin comigratory protein (BCP) peroxiredoxin in tobacco compromised AzA signaling, a prerequisite for LPS-triggered SAR. Western blot analyses revealed that 'Ca. L. asiaticus' BCP peroxiredoxin prevented peroxynitrite-mediated tyrosine nitration in tobacco. 'Ca. L. asiaticus' BCP peroxiredoxin (i) attenuates NO-mediated SAR signaling and (ii) scavenges peroxynitrite radicals, which would facilitate repetitive cycles of 'Ca. L. asiaticus' acquisition and transmission by fecund psyllids throughout the limited flush period in citrus.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Mukesh Jain
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Lulu Cai
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Ian Black
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Russell W Carlson
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Kathryn M Jones
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, U.S.A
| | - Dean W Gabriel
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
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26
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Genomic and Functional Dissections of Dickeya zeae Shed Light on the Role of Type III Secretion System and Cell Wall-Degrading Enzymes to Host Range and Virulence. Microbiol Spectr 2022; 10:e0159021. [PMID: 35107329 PMCID: PMC8809351 DOI: 10.1128/spectrum.01590-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dickeya zeae is a worldwide destructive pathogen that causes soft rot diseases on various hosts such as rice, maize, banana, and potato. The strain JZL7 we recently isolated from clivia represents the first monocot-specific D. zeae and also has reduced pathogenicity compared to that of other D. zeae strains (e.g., EC1 and MS2). To elucidate the molecular mechanisms underlying its more restricted host range and weakened pathogenicity, we sequenced the complete genome of JZL7 and performed comparative genomic and functional analyses of JZL7 and other D. zeae strains. We found that, while having the largest genome among D. zeae strains, JZL7 lost almost the entire type III secretion system (T3SS), which is a key component of the virulence suite of many bacterial pathogens. Importantly, the deletion of T3SS in MS2 substantially diminished the expression of most type III secreted effectors (T3SEs) and MS2's pathogenicity on both dicots and monocots. Moreover, although JZL7 and MS2 share almost the same repertoire of cell wall-degrading enzymes (CWDEs), we found broad reduction in the production of CWDEs and expression levels of CWDE genes in JZL7. The lower expression of CWDEs, pectin lyases in particular, would probably make it difficult for JZL7 to break down the cell wall of dicots, which is rich in pectin. Together, our results suggest that the loss of T3SS and reduced CWDE activity together might have contributed to the host specificity and virulence of JZL7. Our findings also shed light on the pathogenic mechanism of Dickeya and other soft rot Pectobacteriaceae species in general. IMPORTANCE Dickeya zeae is an important, aggressive bacterial phytopathogen that can cause severe diseases in many crops and ornamental plants, thus leading to substantial economic losses. Strains from different sources showed significant diversity in their natural hosts, suggesting complicated evolution history and pathogenic mechanisms. However, molecular mechanisms that cause the differences in the host range of D. zeae strains remain poorly understood. This study carried out genomic and functional dissections of JZL7, a D. zeae strain with restricted host range, and revealed type III secretion system (T3SS) and cell wall-degrading enzymes (CWDEs) as two major factors contributing to the host range and virulence of D. zeae, which will provide a valuable reference for the exploration of pathogenic mechanisms in other bacteria and present new insights for the control of bacterial soft rot diseases on crops.
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Malvino ML, Bott AJ, Green CE, Majumdar T, Hind SR. Influence of Flagellin Polymorphisms, Gene Regulation, and Responsive Memory on the Motility of Xanthomonas Species That Cause Bacterial Spot Disease of Solanaceous Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:157-169. [PMID: 34732057 DOI: 10.1094/mpmi-08-21-0211-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Increasingly, new evidence has demonstrated variability in the epitope regions of bacterial flagellin, including in regions harboring the microbe-associated molecular patterns flg22 and flgII-28 that are recognized by the pattern recognition receptors FLS2 and FLS3, respectively. Additionally, because bacterial motility is known to contribute to pathogen virulence and chemotaxis, reductions in or loss of motility can significantly reduce bacterial fitness. In this study, we determined that variations in flg22 and flgII-28 epitopes allow some but not all Xanthomonas spp. to evade both FLS2- and FLS3-mediated oxidative burst responses. We observed variation in the motility for many isolates, regardless of their flagellin sequence. Instead, we determined that past growth conditions may have a significant impact on the motility status of isolates, because we could minimize this variability by inducing motility using chemoattractant assays. Additionally, motility could be significantly suppressed under nutrient-limited conditions, and bacteria could "remember" its prior motility status after storage at ultracold temperatures. Finally, we observed larger bacterial populations of strains with flagellin variants predicted not to be recognized by either FLS2 or FLS3, suggesting that these bacteria can evade flagellin recognition in tomato plants. Although some flagellin variants may impart altered motility and differential recognition by the host immune system, external growth parameters and gene expression regulation appear to have more significant impacts on the motility phenotypes for these Xanthomonas spp.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Maria L Malvino
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Amie J Bott
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Cory E Green
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Tanvi Majumdar
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Sarah R Hind
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
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Klein-Gordon JM, Timilsina S, Xing Y, Abrahamian P, Garrett KA, Jones JB, Vallad GE, Goss EM. Whole genome sequences reveal the Xanthomonas perforans population is shaped by the tomato production system. THE ISME JOURNAL 2022; 16:591-601. [PMID: 34489540 PMCID: PMC8776747 DOI: 10.1038/s41396-021-01104-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 08/11/2021] [Accepted: 08/23/2021] [Indexed: 02/08/2023]
Abstract
Modern agricultural practices increase the potential for plant pathogen spread, while the advent of affordable whole genome sequencing enables in-depth studies of pathogen movement. Population genomic studies may decipher pathogen movement and population structure as a result of complex agricultural production systems. We used whole genome sequences of 281 Xanthomonas perforans strains collected within one tomato production season across Florida and southern Georgia fields to test for population genetic structure associated with tomato production system variables. We identified six clusters of X. perforans from core gene SNPs that corresponded with phylogenetic lineages. Using whole genome SNPs, we found genetic structure among farms, transplant facilities, cultivars, seed producers, grower operations, regions, and counties. Overall, grower operations that produced their own transplants were associated with genetically distinct and less diverse populations of strains compared to grower operations that received transplants from multiple sources. The degree of genetic differentiation among components of Florida's tomato production system varied between clusters, suggesting differential dispersal of the strains, such as through seed or contaminated transplants versus local movement within farms. Overall, we showed that the genetic variation of a bacterial plant pathogen is shaped by the structure of the plant production system.
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Affiliation(s)
- Jeannie M Klein-Gordon
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Sujan Timilsina
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
| | - Yanru Xing
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
- Food Systems Institute, University of Florida, Gainesville, FL, USA
| | - Peter Abrahamian
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
- Gulf Coast Research and Education Center, IFAS, University of Florida, Balm, FL, USA
- USDA-ARS, Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, Beltsville, MD, USA
| | - Karen A Garrett
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
- Food Systems Institute, University of Florida, Gainesville, FL, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA
| | - Gary E Vallad
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA.
- Gulf Coast Research and Education Center, IFAS, University of Florida, Balm, FL, USA.
| | - Erica M Goss
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
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29
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Haq F, Xu X, Ma W, Shah SMA, Liu L, Zhu B, Zou L, Chen G. A Xanthomonas transcription activator-like effector is trapped in nonhost plants for immunity. PLANT COMMUNICATIONS 2022; 3:100249. [PMID: 35059629 PMCID: PMC8760140 DOI: 10.1016/j.xplc.2021.100249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/29/2021] [Accepted: 10/13/2021] [Indexed: 05/10/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight in rice, delivers transcription activator-like effector (TALE) proteins into host cells to activate susceptibility or resistance (R) genes that promote disease or immunity, respectively. Nonhost plants serve as potential reservoirs of R genes; consequently, nonhost R genes may trap TALEs to trigger an immune response. In this study, we screened 17 Xoo TALEs for their ability to induce a hypersensitive response (HR) in the nonhost plant Nicotiana benthamiana (Nb); only AvrXa10 elicited an HR when transiently expressed in Nb. The HR generated by AvrXa10 required both the central repeat region and the activation domain, suggesting a specific interaction between AvrXa10 and a potential R-like gene in nonhost plants. Evans blue staining and ion leakage measurements confirmed that the AvrXa10-triggered HR was a form of cell death, and the transient expression of AvrXa10 in Nb induced immune responses. Genes targeted by AvrXa10 in the Nb genome were identified by transcriptome profiling and prediction of effector binding sites. Using several approaches (in vivo reporter assays, electrophoretic mobility-shift assays, targeted designer TALEs, and on-spot gene silencing), we confirmed that AvrXa10 targets NbZnFP1, a C2H2-type zinc finger protein that resides in the nucleus. Functional analysis indicated that overexpression of NbZnFP1 and its rice orthologs triggered cell death in rice protoplasts. An NbZnFP1 ortholog was also identified in tomato and was specifically activated by AvrXa10. These results demonstrate that NbZnFP1 is a nonhost R gene that traps AvrXa10 to promote plant immunity in Nb.
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Affiliation(s)
- Fazal Haq
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Xiameng Xu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Wenxiu Ma
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Syed Mashab Ali Shah
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Linlin Liu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Bo Zhu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Lifang Zou
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
| | - Gongyou Chen
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture of the Ministry of Agriculture, Shanghai, 200240, China
- Corresponding author
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30
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Osdaghi E, Jones JB, Sharma A, Goss EM, Abrahamian P, Newberry EA, Potnis N, Carvalho R, Choudhary M, Paret ML, Timilsina S, Vallad GE. A centenary for bacterial spot of tomato and pepper. MOLECULAR PLANT PATHOLOGY 2021; 22:1500-1519. [PMID: 34472193 PMCID: PMC8578828 DOI: 10.1111/mpp.13125] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 05/08/2023]
Abstract
DISEASE SYMPTOMS Symptoms include water-soaked areas surrounded by chlorosis turning into necrotic spots on all aerial parts of plants. On tomato fruits, small, water-soaked, or slightly raised pale-green spots with greenish-white halos are formed, ultimately becoming dark brown and slightly sunken with a scabby or wart-like surface. HOST RANGE Main and economically important hosts include different types of tomatoes and peppers. Alternative solanaceous and nonsolanaceous hosts include Datura spp., Hyoscyamus spp., Lycium spp., Nicotiana rustica, Physalis spp., Solanum spp., Amaranthus lividus, Emilia fosbergii, Euphorbia heterophylla, Nicandra physaloides, Physalis pubescens, Sida glomerata, and Solanum americanum. TAXONOMIC STATUS OF THE PATHOGEN Domain, Bacteria; phylum, Proteobacteria; class, Gammaproteobacteria; order, Xanthomonadales; family, Xanthomonadaceae; genus, Xanthomonas; species, X. euvesicatoria, X. hortorum, X. vesicatoria. SYNONYMS (NONPREFERRED SCIENTIFIC NAMES) Bacterium exitiosum, Bacterium vesicatorium, Phytomonas exitiosa, Phytomonas vesicatoria, Pseudomonas exitiosa, Pseudomonas gardneri, Pseudomonas vesicatoria, Xanthomonas axonopodis pv. vesicatoria, Xanthomonas campestris pv. vesicatoria, Xanthomonas cynarae pv. gardneri, Xanthomonas gardneri, Xanthomonas perforans. MICROBIOLOGICAL PROPERTIES Colonies are gram-negative, oxidase-negative, and catalase-positive and have oxidative metabolism. Pale-yellow domed circular colonies of 1-2 mm in diameter grow on general culture media. DISTRIBUTION The bacteria are widespread in Africa, Brazil, Canada and the USA, Australia, eastern Europe, and south-east Asia. Occurrence in western Europe is restricted. PHYTOSANITARY CATEGORIZATION A2 no. 157, EU Annex designation II/A2. EPPO CODES XANTEU, XANTGA, XANTPF, XANTVE.
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Affiliation(s)
- Ebrahim Osdaghi
- Department of Plant ProtectionCollege of AgricultureUniversity of TehranKarajIran
| | - Jeffrey B. Jones
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
| | - Anuj Sharma
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
| | - Erica M. Goss
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
- Emerging Pathogens InstituteUniversity of FloridaGainesvilleFloridaUSA
| | - Peter Abrahamian
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
- Gulf Coast Research and Education CenterUniversity of FloridaWimaumaFloridaUSA
| | - Eric A. Newberry
- Department of Entomology and Plant PathologyAuburn UniversityAuburnAlabamaUSA
| | - Neha Potnis
- Department of Entomology and Plant PathologyAuburn UniversityAuburnAlabamaUSA
| | - Renato Carvalho
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
| | - Manoj Choudhary
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
| | - Mathews L. Paret
- Department of Plant PathologyNorth Florida Research and Education CenterUniversity of FloridaQuincyFloridaUSA
| | - Sujan Timilsina
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFloridaUSA
| | - Gary E. Vallad
- Gulf Coast Research and Education CenterUniversity of FloridaWimaumaFloridaUSA
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Hu M, Li C, Zhou X, Xue Y, Wang S, Hu A, Chen S, Mo X, Zhou J. Microbial Diversity Analysis and Genome Sequencing Identify Xanthomonas perforans as the Pathogen of Bacterial Leaf Canker of Water Spinach ( Ipomoea aquatic). Front Microbiol 2021; 12:752760. [PMID: 34777306 PMCID: PMC8579042 DOI: 10.3389/fmicb.2021.752760] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/22/2021] [Indexed: 11/13/2022] Open
Abstract
Ipomoea aquatica is a leafy vegetable widely cultivated in tropical Asia, Africa, and Oceania. Bacterial leaf canker disease has been attacking the planting fields and seriously affecting the quality of I. aquatica in epidemic areas in China. This study examined the microbial composition of I. aquatica leaves with classical symptoms of spot disease. The results showed that Xanthomonas was overwhelmingly dominant in all four diseased leaf samples but rarely present in rhizospheric soil or irrigation water samples. In addition, Pantoea was also detected in two of the diseased leaf samples. Pathogen isolation, identification, and inoculation revealed that both Xanthomonas sp. TC2-1 and P. ananatis were pathogenic to the leaves of I. aquatic, causing crater-shaped ulcerative spots and yellowing with big brown rot lesions on leaves, respectively. We further sequenced the whole genome of strain TC2-1 and showed that it is a member of X. perforans. Overall, this study identified X. perforans as the causal pathogen of I. aquatica bacterial leaf canker, and P. ananatis as a companion pathogen causing yellowing and brown rot on leaves. The correct identification of the pathogens will provide important basis for future efforts to formulate targeted application strategy for bacterial disease control.
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Affiliation(s)
- Ming Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Chuhao Li
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiaofan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Yang Xue
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Si Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Anqun Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Shanshan Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiuwen Mo
- Agricultural Technology Service Centre of Daojiao Town, Dongguan, China
| | - Jianuan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
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32
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Sharma A, Timilsina S, Abrahamian P, Minsavage GV, Colee J, Ojiambo PS, Goss EM, Vallad GE, Jones JB. Need for speed: bacterial effector XopJ2 is associated with increased dispersal velocity of Xanthomonas perforans. Environ Microbiol 2021; 23:5850-5865. [PMID: 33891376 PMCID: PMC8597037 DOI: 10.1111/1462-2920.15541] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/20/2021] [Indexed: 11/28/2022]
Abstract
Bacterial spot caused by Xanthomonas perforans (Xp) is an economically important disease in tomato. Previous studies have shown that the recently isolated Xp strains have acquired and retained the effector gene, xopJ2, which has been reported to increase fitness of the pathogen in the field. To elucidate the fitness benefit of xopJ2, we quantified the effect of xopJ2 on the dispersal and evolution of Xp populations on tomato. We compared movement of two wild-type Xp strains expressing xopJ2 to their respective xopJ2 mutants when co-inoculated in the field. We developed a binary logistic model to predict the presence of Xp over spatial and temporal dimensions with or without xopJ2. Based on the model, wild-type bacteria were dispersed approximately three times faster than the xopJ2 mutants. In a simulation experiment, the selective advantage due to increased dispersal velocity led to an increase in the frequency of xopJ2 gene in the Xp population and its apparent fixation within 10 to 12 cropping seasons of the tomato crop. Our results show that the presence of a single gene can affect the dispersal of a bacterial pathogen and significantly alter its population dynamics.
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Affiliation(s)
- Anuj Sharma
- Department of Plant PathologyUniversity of FloridaGainesvilleFloridaUSA
| | - Sujan Timilsina
- Department of Plant PathologyUniversity of FloridaGainesvilleFloridaUSA
| | - Peter Abrahamian
- Gulf Coast Research and Education CenterUniversity of FloridaWimaumaFloridaUSA
| | | | - James Colee
- Statistics Consulting Unit, Institute of Food and Agricultural SciencesUniversity of FloridaGainesvilleFloridaUSA
| | - Peter S. Ojiambo
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Erica M. Goss
- Department of Plant PathologyUniversity of FloridaGainesvilleFloridaUSA
- Emerging Pathogens InstituteUniversity of FloridaGainesvilleFloridaUSA
| | - Gary E. Vallad
- Gulf Coast Research and Education CenterUniversity of FloridaWimaumaFloridaUSA
| | - Jeffrey B. Jones
- Department of Plant PathologyUniversity of FloridaGainesvilleFloridaUSA
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Teper D, Xu J, Pandey SS, Wang N. PthAW1, a Transcription Activator-Like Effector of Xanthomonas citri subsp. citri, Promotes Host-Specific Immune Responses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1033-1047. [PMID: 33970668 DOI: 10.1094/mpmi-01-21-0026-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Citrus canker disease caused by Xanthomonas citri subsp. citri is one of the most destructive diseases in citrus. X. citri subsp. citri pathotypes display different host ranges. X. citri subsp. citri strain A (XccA) causes canker disease in most commercial citrus varieties, whereas strain AW (XccAW), which is genetically similar to XccA, infects only lime and alemow. Understanding the mechanism that determines the host range of pathogens is critical to investigating and utilizing host resistance. We hypothesized that XccAW would undergo mutations in genes that restrict its host range when artificially inoculated into incompatible citrus varieties. To test this hypothesis, we used an experimental evolution approach to identify phenotypic traits and genetic loci associated with the adaptation of XccAW to incompatible sweet orange. Repeated inoculation and reisolation cycles improved the ability of three independent XccAW strains to colonize sweet orange. Adapted XccAW strains displayed increased expression of type III secretion system and effector genes. Genome sequencing analysis indicated that two of the adapted strains harbored mutations in pthAW1, a transcription activator-like effector (TALE) gene, that corresponded to the removal of one or two repeats from the central DNA-binding repeat region. Introduction of the original but not the adapted pthAW1 variants into XccA abolished its ability to cause canker symptoms in sweet orange, Meyer lemon, and clementine but not in other XccAW-resistant citrus varieties. The original pthAW1, when expressed in XccA, induced ion leakage and the expression of pathogenesis-related genes but had no effect on CsLOB1 expression in sweet orange. Our study has identified a novel host-specific avirulence TALE and demonstrated active adaptive rearrangements of the TALE repeat array during host adaptation.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Doron Teper
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
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34
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Bi G, Zhou JM. Regulation of Cell Death and Signaling by Pore-Forming Resistosomes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:239-263. [PMID: 33957051 DOI: 10.1146/annurev-phyto-020620-095952] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nucleotide-binding leucine-rich repeat receptors (NLRs) are the largest class of immune receptors in plants. They play a key role in the plant surveillance system by monitoring pathogen effectors that are delivered into the plant cell. Recent structural biology and biochemical analyses have uncovered how NLRs are activated to form oligomeric resistosomes upon the recognition of pathogen effectors. In the resistosome, the signaling domain of the NLR is brought to the center of a ringed structure to initiate immune signaling and regulated cell death (RCD). The N terminus of the coiled-coil (CC) domain of the NLR protein HOPZ-ACTIVATED RESISTANCE 1 likely forms a pore in the plasma membrane to trigger RCD in a way analogous to animal pore-forming proteins that trigger necroptosis or pyroptosis. NLRs that carry TOLL-INTERLEUKIN1-RECEPTOR as a signaling domain may also employ pore-forming resistosomes for RCD execution. In addition, increasing evidence supports intimate connections between NLRs and surface receptors in immune signaling. These new findings are rapidly advancing our understanding of the plant immune system.
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Affiliation(s)
- Guozhi Bi
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China;
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China;
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
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35
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Potnis N. Harnessing Eco-Evolutionary Dynamics of Xanthomonads on Tomato and Pepper to Tackle New Problems of an Old Disease. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:289-310. [PMID: 34030449 DOI: 10.1146/annurev-phyto-020620-101612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bacterial spot is an endemic seedborne disease responsible for recurring outbreaks on tomato and pepper around the world. The disease is caused by four diverse species, Xanthomonas gardneri, Xanthomonas euvesicatoria, Xanthomonas perforans, and Xanthomonas vesicatoria. There are no commercially available disease-resistant tomato varieties, and the disease is managed by chemical/biological control options, although these have not reduced the incidence of outbreaks. The disease on peppers is managed by disease-resistant cultivars that are effective against X. euvesicatoria but not X. gardneri. A significant shift in composition and prevalence of different species and races of the pathogen has occurred over the past century. Here, I attempt to review ecological and evolutionary processes associated with the population dynamics leading to disease emergence and spread. The goal of this review is to integrate the knowledge on population genomics and molecular plant-microbe interactions for this pathosystem to tailor disease management strategies.
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Affiliation(s)
- Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama 36849, USA;
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36
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Abrahamian P, Klein-Gordon JM, Jones JB, Vallad GE. Epidemiology, diversity, and management of bacterial spot of tomato caused by Xanthomonas perforans. Appl Microbiol Biotechnol 2021; 105:6143-6158. [PMID: 34342710 DOI: 10.1007/s00253-021-11459-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/05/2021] [Accepted: 07/09/2021] [Indexed: 11/28/2022]
Abstract
Tomato is an important crop grown worldwide. Various plant diseases cause massive losses in tomato plants due to diverse biotic agents. Bacterial spot of tomato (BST) is a worldwide disease that results in high losses in processed and fresh tomato. Xanthomonas perforans, an aerobic, single-flagellated, rod-shaped, Gram-negative plant pathogenic bacterium, is one of the leading causes of BST. Over the past three decades, X. perforans has increasingly been reported from tomato-growing regions and became a major bacterial disease. X. perforans thrives under high humidity and high temperature, which is commonplace in tropical and subtropical climates. Distinguishing symptoms of BST are necrotic lesions that can coalesce and cause a shot-hole appearance. X. perforans can occasionally cause fruit symptoms depending on disease pressure during fruit development. Short-distance movement in the field is mainly dependent on wind-driven rain, whereas long distance movement occurs through contaminated seed or plant material. X. perforans harbors a suite of effectors that increase pathogen virulence, fitness, and dissemination. BST management mainly relies on copper-based compounds; however, resistance is widespread. Alternative compounds, such as nanomaterials, are currently being evaluated and show high potential for BST management. Resistance breeding remains difficult to attain due to limited resistant germplasm. While the increased genetic diversity and gain and loss of effectors in X. perforans limits the success of single-gene resistance, the adoption of effector-specific transgenes and quantitative resistance may lead to durable host resistance. However, further research that aims to more effectively implement novel management tools is required to curb disease spread. KEY POINTS: • Xanthomonas perforans causes bacterial spot on tomato epidemics through infected seedlings and movement of plant material. • Genetic diversity plays a major role in shaping populations which is evident in loss and gain of effectors. • Management relies on copper sprays, but nanoparticles are a promising alternative to reduce copper toxicity.
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Affiliation(s)
- Peter Abrahamian
- Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, USDA-ARS, Beltsville, MD, 20705, USA.
| | | | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Gary E Vallad
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA.
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37
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Rai R, Pasion J, Majumdar T, Green CE, Hind SR. Genome Sequencing and Functional Characterization of Xanthomonas cucurbitae, the Causal Agent of Bacterial Spot Disease of Cucurbits. PHYTOPATHOLOGY 2021; 111:1289-1300. [PMID: 33734871 DOI: 10.1094/phyto-06-20-0228-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bacterial leaf spot disease caused by Xanthomonas cucurbitae has severely affected the pumpkin industries in the Midwestern region of United States, with the bacteria mainly infecting pumpkin leaves and fruits, and leading to significant yield losses. In this study, we utilized genomics and genetics approaches to elucidate X. cucurbitae molecular mechanisms of pathogenesis during interaction with its host. We generated the first reference-quality whole-genome sequence of the X. cucurbitae type isolate and compared with other Xanthomonas species, X. cucurbitae has a smaller genome size with fewer virulence-related genes. RNA-seq analysis of X. cucurbitae under plant-mimicking media conditions showed altered transcriptional responses, with upregulation of virulence genes and downregulation of cellular homeostasis genes. Additionally, characterization of key virulence genes using gene deletion methods revealed that both type II enzymes and type III effectors are necessary for X. cucurbitae to cause infection in the pumpkin host.
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Affiliation(s)
- Rikky Rai
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Julius Pasion
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Tanvi Majumdar
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Cory E Green
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Sarah R Hind
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
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38
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Thomazella DPDT, Seong K, Mackelprang R, Dahlbeck D, Geng Y, Gill US, Qi T, Pham J, Giuseppe P, Lee CY, Ortega A, Cho MJ, Hutton SF, Staskawicz B. Loss of function of a DMR6 ortholog in tomato confers broad-spectrum disease resistance. Proc Natl Acad Sci U S A 2021; 118:2026152118. [PMID: 34215692 DOI: 10.1101/064824] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023] Open
Abstract
Plant diseases are among the major causes of crop yield losses around the world. To confer disease resistance, conventional breeding relies on the deployment of single resistance (R) genes. However, this strategy has been easily overcome by constantly evolving pathogens. Disabling susceptibility (S) genes is a promising alternative to R genes in breeding programs, as it usually offers durable and broad-spectrum disease resistance. In Arabidopsis, the S gene DMR6 (AtDMR6) encodes an enzyme identified as a susceptibility factor to bacterial and oomycete pathogens. Here, we present a model-to-crop translational work in which we characterize two AtDMR6 orthologs in tomato, SlDMR6-1 and SlDMR6-2. We show that SlDMR6-1, but not SlDMR6-2, is up-regulated by pathogen infection. In agreement, Sldmr6-1 mutants display enhanced resistance against different classes of pathogens, such as bacteria, oomycete, and fungi. Notably, disease resistance correlates with increased salicylic acid (SA) levels and transcriptional activation of immune responses. Furthermore, we demonstrate that SlDMR6-1 and SlDMR6-2 display SA-5 hydroxylase activity, thus contributing to the elucidation of the enzymatic function of DMR6. We then propose that SlDMR6 duplication in tomato resulted in subsequent subfunctionalization, in which SlDMR6-2 specialized in balancing SA levels in flowers/fruits, while SlDMR6-1 conserved the ability to fine-tune SA levels during pathogen infection of the plant vegetative tissues. Overall, this work not only corroborates a mechanism underlying SA homeostasis in plants, but also presents a promising strategy for engineering broad-spectrum and durable disease resistance in crops.
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Affiliation(s)
- Daniela Paula de Toledo Thomazella
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
| | - Kyungyong Seong
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Rebecca Mackelprang
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Douglas Dahlbeck
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
| | - Yu Geng
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Upinder S Gill
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108
| | - Tiancong Qi
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Julie Pham
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
| | - Priscila Giuseppe
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas SP 13083-100, Brazil
| | - Clara Youngna Lee
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Arturo Ortega
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
| | - Myeong-Je Cho
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
| | - Samuel F Hutton
- Horticultural Sciences Department, University of Florida, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Brian Staskawicz
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720;
- Innovative Genomics Institute, University of California, Berkeley, CA 94704
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39
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Genome editing for resistance against plant pests and pathogens. Transgenic Res 2021; 30:427-459. [PMID: 34143358 DOI: 10.1007/s11248-021-00262-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 05/27/2021] [Indexed: 12/12/2022]
Abstract
The conventional breeding of crops struggles to keep up with increasing food needs and ever-adapting pests and pathogens. Global climate changes have imposed another layer of complexity to biological systems, increasing the challenge to obtain improved crop cultivars. These dictate the development and application of novel technologies, like genome editing (GE), that assist targeted and fast breeding programs in crops, with enhanced resistance to pests and pathogens. GE does not require crossings, hence avoiding the introduction of undesirable traits through linkage in elite varieties, speeding up the whole breeding process. Additionally, GE technologies can improve plant protection by directly targeting plant susceptibility (S) genes or virulence factors of pests and pathogens, either through the direct edition of the pest genome or by adding the GE machinery to the plant genome or to microorganisms functioning as biocontrol agents (BCAs). Over the years, GE technology has been continuously evolving and more so with the development of CRISPR/Cas. Here we review the latest advancements of GE to improve plant protection, focusing on CRISPR/Cas-based genome edition of crops and pests and pathogens. We discuss how other technologies, such as host-induced gene silencing (HIGS) and the use of BCAs could benefit from CRISPR/Cas to accelerate the development of green strategies to promote a sustainable agriculture in the future.
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40
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Srivastava V, Deblais L, Kathayat D, Rotondo F, Helmy YA, Miller SA, Rajashekara G. Novel Small Molecule Growth Inhibitors of Xanthomonas spp. Causing Bacterial Spot of Tomato. PHYTOPATHOLOGY 2021; 111:940-953. [PMID: 34311554 DOI: 10.1094/phyto-08-20-0341-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bacterial spot (BS) of tomato, caused by Xanthomonas gardneri, X. perforans, X. vesicatoria, and X. euvesicatoria, is difficult to control because of the high prevalence of copper- and streptomycin-resistant strains and the lack of resistance cultivars and effective bactericides. The objective of this study was to identify novel growth inhibitors of BS-causing Xanthomonas (BS-X) species by using small molecules (SM; n = 4,182). Several SMs (X1, X2, X5, X9, X12, and X16) completely inhibited the growth of BS-X isolates (n = 68 X. gardneri, 55 X. perforans, 4 X. vesicatoria, and 32 X. euvesicatoria) at ≥12.5 µM by disrupting Xanthomonas cell integrity through weakening of the cell membrane and formation of pores. These SMs were also effective against biofilm-embedded, copper- and streptomycin-resistant Xanthomonas strains while having minimal impact on other plant pathogenic (n = 20) and beneficial bacteria (n = 12). Furthermore, these SMs displayed equivalent antimicrobial activity against BS-X in seeds and X. gardneri in seedlings compared with conventional control methods (copper sulfate and streptomycin) at similar concentrations while having no detectable toxicity to tomato tissues. SMs X2, X5, and X12 reduced X. gardneri, X. perforans, X. vesicatoria, and X. euvesicatoria populations in artificially infested seeds ≤3.4-log CFU/seed 1 day postinfection (dpi) compared with the infested untreated control (P ≤ 0.05). SMs X1, X2, X5, and X12 reduced disease severity ≤72% and engineered bioluminescent X. gardneri populations ≤3.0-log CFU/plant in infected seedlings at 7 dpi compared with the infected untreated control (P ≤ 0.05). Additional studies are needed to increase the applicability of these SMs for BS management in tomato production.
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Affiliation(s)
- Vishal Srivastava
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH
| | - Loic Deblais
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH
| | - Dipak Kathayat
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH
| | - Francesca Rotondo
- Department of Plant Pathology, The Ohio State University, Wooster, OH
| | - Yosra A Helmy
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH
| | - Sally A Miller
- Department of Plant Pathology, The Ohio State University, Wooster, OH
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH
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Klein-Gordon JM, Xing Y, Garrett KA, Abrahamian P, Paret ML, Minsavage GV, Strayer-Scherer AL, Fulton JC, Timilsina S, Jones JB, Goss EM, Vallad GE. Assessing Changes and Associations in the Xanthomonas perforans Population Across Florida Commercial Tomato Fields Via a Statewide Survey. PHYTOPATHOLOGY 2021; 111:1029-1041. [PMID: 33048630 DOI: 10.1094/phyto-09-20-0402-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Before 1991, Xanthomonas euvesicatoria was the causal agent of bacterial spot of tomato in Florida but was quickly replaced by X. perforans. The X. perforans population has changed in genotype and phenotype despite lack of a clear selection pressure. To determine the current Xanthomonas population in Florida, we collected 585 Xanthomonas strains from 70 tomato fields, representing 22 farms across eight counties, in the Florida tomato production region. Strains were isolated from 23 cultivars across eight seed producers and were associated with eight transplant facilities during the fall 2017 season. Our collection was phenotypically and genotypically characterized. Only X. perforans was identified, and all strains except one (99.8%) were tolerant to copper sulfate and 25% of strains were resistant to streptomycin sulfate. Most of the strains (99.3%) that were resistant to streptomycin sulfate were sequence type 1. The X. perforans population consisted of tomato races 3 (8%) and 4 (92%) and all three previously reported sequence types, ranging from 22 to 46% frequency. Approximately half of all strains, none of which were sequence type 2, produced bacteriocins against X. euvesicatoria. Effector profiles were highly variable among strains, which could impact the strains' host range. The effector xopJ4, which was previously thought to be conserved in X. perforans tomato pathogens, was absent in 19 strains. Nonmetric multidimensional scaling and network analyses show how strains and strain traits were associated with production system variables, including anonymized farms and transplant facilities. These analyses show that the composition of the Florida X. perforans population is diverse and complex.
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Affiliation(s)
- Jeannie M Klein-Gordon
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
| | - Yanru Xing
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
- Food Systems Institute, University of Florida, Gainesville, FL 32611
| | - Karen A Garrett
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
- Food Systems Institute, University of Florida, Gainesville, FL 32611
| | - Peter Abrahamian
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Gulf Coast Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Balm, FL 33598
| | - Matthews L Paret
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- North Florida Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Quincy, FL 32351
| | - Gerald V Minsavage
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
| | | | - James C Fulton
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
| | - Sujan Timilsina
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
| | - Jeffrey B Jones
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
| | - Erica M Goss
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
| | - Gary E Vallad
- Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
- Gulf Coast Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Balm, FL 33598
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Sacristán S, Goss EM, Eves-van den Akker S. How Do Pathogens Evolve Novel Virulence Activities? MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:576-586. [PMID: 33522842 DOI: 10.1094/mpmi-09-20-0258-ia] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This article is part of the Top 10 Unanswered Questions in MPMI invited review series.We consider the state of knowledge on pathogen evolution of novel virulence activities, broadly defined as anything that increases pathogen fitness with the consequence of causing disease in either the qualitative or quantitative senses, including adaptation of pathogens to host immunity and physiology, host species, genotypes, or tissues, or the environment. The evolution of novel virulence activities as an adaptive trait is based on the selection exerted by hosts on variants that have been generated de novo or arrived from elsewhere. In addition, the biotic and abiotic environment a pathogen experiences beyond the host may influence pathogen virulence activities. We consider host-pathogen evolution, host range expansion, and external factors that can mediate pathogen evolution. We then discuss the mechanisms by which pathogens generate and recombine the genetic variation that leads to novel virulence activities, including DNA point mutation, transposable element activity, gene duplication and neofunctionalization, and genetic exchange. In summary, if there is an (epi)genetic mechanism that can create variation in the genome, it will be used by pathogens to evolve virulence factors. Our knowledge of virulence evolution has been biased by pathogen evolution in response to major gene resistance, leaving other virulence activities underexplored. Understanding the key driving forces that give rise to novel virulence activities and the integration of evolutionary concepts and methods with mechanistic research on plant-microbe interactions can help inform crop protection.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Soledad Sacristán
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo-UPM, 28223-Pozuelo de Alarcón (Madrid), Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, 28040-Madrid, Spain
| | - Erica M Goss
- Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, U.S.A
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Vancheva T, Bogatzevska N, Moncheva P, Mitrev S, Vernière C, Koebnik R. Molecular Epidemiology of Xanthomonas euvesicatoria Strains from the Balkan Peninsula Revealed by a New Multiple-Locus Variable-Number Tandem-Repeat Analysis Scheme. Microorganisms 2021; 9:microorganisms9030536. [PMID: 33807692 PMCID: PMC8002079 DOI: 10.3390/microorganisms9030536] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/25/2021] [Accepted: 03/01/2021] [Indexed: 11/24/2022] Open
Abstract
Bacterial spot of pepper and tomato is caused by at least three species of Xanthomonas, among them two pathovars of Xanthomonas euvesicatoria, which are responsible for significant yield losses on all continents. In order to trace back the spread of bacterial spot pathogens within and among countries, we developed the first multilocus variable number of tandem repeat analyses (MLVA) scheme for pepper- and tomato-pathogenic strains of X. euvesicatoria. In this work, we assessed the repeat numbers by DNA sequencing of 16 tandem repeat loci and applied this new tool to analyse a representative set of 88 X. euvesicatoria pepper strains from Bulgaria and North Macedonia. The MLVA-16 scheme resulted in a Hunter–Gaston Discriminatory Index (HGDI) score of 0.944 and allowed to resolve 36 MLVA haplotypes (MTs), thus demonstrating its suitability for high-resolution molecular typing. Strains from the different regions of Bulgaria and North Macedonia were found to be widespread in genetically distant clonal complexes or singletons. Sequence types of the variable number of tandem repeats (VNTR) amplicons revealed cases of size homoplasy and suggested the coexistence of different populations and different introduction events. The large geographical distribution of MTs and the existence of epidemiologically closely related strains in different regions and countries suggest long dispersal of strains on pepper in this area.
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Affiliation(s)
- Taca Vancheva
- IPME, Univ Montpellier, Cirad, IRD, Montpellier, France;
- Department of General and Industrial Microbiology, Faculty of Biology, Sofia University ‘St. Kliment Ohridski’, Sofia, Bulgaria;
| | - Nevena Bogatzevska
- Institute of Soil Science, Agrotechnologies and Plant Protection ‘Nikola Pushkarov’, Sofia, Bulgaria;
| | - Penka Moncheva
- Department of General and Industrial Microbiology, Faculty of Biology, Sofia University ‘St. Kliment Ohridski’, Sofia, Bulgaria;
| | - Sasa Mitrev
- Department for Plant and Environment Protection, Faculty of Agriculture, Goce Delchev University, Štip, North Macedonia;
| | - Christian Vernière
- Plant Health Institute of Montpellier (PHIM), Univ Montpellier, Cirad, INRAe, Insitut Agro, IRD, Montpellier, France;
| | - Ralf Koebnik
- IPME, Univ Montpellier, Cirad, IRD, Montpellier, France;
- Plant Health Institute of Montpellier (PHIM), Univ Montpellier, Cirad, INRAe, Insitut Agro, IRD, Montpellier, France;
- Correspondence: ; Tel.: +33-467-416-228
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Abrahamian P, Sharma A, Jones JB, Vallad GE. Dynamics and Spread of Bacterial Spot Epidemics in Tomato Transplants Grown for Field Production. PLANT DISEASE 2021; 105:566-575. [PMID: 32865478 DOI: 10.1094/pdis-05-20-0945-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Tomato transplants are the primary means of establishing commercial tomato production fields in the eastern United States. Transplants are often suspected as the source of inoculum for major outbreaks in production fields of bacterial spot of tomato (BST) caused by Xanthomonas perforans (Xp). A combination of high plant densities with overhead irrigation, high humidity, and high temperatures are conducive to BST outbreaks during transplant production. In addition to chemical control, transplant growers use roguing to remove diseased transplants, as a primary way to manage BST during transplant production. The value of roguing is often questioned, because information about the rate of pathogen spread and the incubation period between infection and symptom development is limited. In this study, we evaluated the extent of X. perforans spread on tomato transplants relative to symptom development by using a rifampicin-resistant X. perforans strain and conducting experiments in an environmentally controlled greenhouse simulating grower practices and also at a commercial transplant facility in Florida. BST symptom development typically lagged behind X. perforans dispersal by at least 5 to 7 days depending on environmental conditions. Furthermore, X. perforans was capable of aerosolization, which resulted in long-distance dispersal of ≤2 m under highly favorable conditions. Growers should rogue diseased plants and surrounding nonsymptomatic plants by >1 and ≤3 m, depending on outbreak severity, to limit disease spread. As a result, proper disease management should reduce introduction of nonsymptomatic transplants into the field and subsequently reduce pesticide applications.
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Affiliation(s)
| | - Anuj Sharma
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Gary E Vallad
- Gulf Coast Research and Education Center, Wimauma, FL 33598
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Zhang X, Li N, Liu X, Wang J, Zhang Y, Liu D, Wang Y, Cao H, Zhao B, Yang W. Tomato protein Rx4 mediates the hypersensitive response to Xanthomonas euvesicatoria pv. perforans race T3. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1630-1644. [PMID: 33345374 DOI: 10.1111/tpj.15138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/06/2020] [Accepted: 12/15/2020] [Indexed: 06/12/2023]
Abstract
Bacterial spot, which is caused by several Xanthomonas species, is an economically important disease in tomato (Solanum lycopersicum). Great efforts have been made for the identification of resistant sources and the genetic analysis of resistance. However, the development of resistant commercial varieties is slow due to the existence of multiple species of the pathogen and a poor understanding of the resistance mechanism in tomato. The current study revealed that the Rx4 gene encodes a nucleotide-binding leucine-rich repeat protein in the wild tomato species Solanum pimpinellifolium and specifically recognizes and confers a hypersensitive response (HR) to Xanthomonas euvesicatoria pv. perforans race T3 expressing the AvrXv3 avirulence protein. Complementation of the Rx4 gene in the susceptible tomato line Ohio 88119 using a transgenic approach resulted in HR, whereas knockout of the gene through CRISPR/Cas9 editing in resistant lines Hawaii 7981 and PI 128216 led to non-HR to race T3. Transcription of Rx4 was not induced by the presence of race T3. Furthermore, the Rx4 protein did not show physical interaction with AvrXv3 but interacted with SGT1-1 and RAR1. Virus-induced gene silencing of SGT1-1 and RAR1 in the resistant line PI128216 suppressed the HR to race T3. Taken together, our study confirms Rx4 is the gene conferring the HR to bacterial spot race T3 and reveals the potential roles of SGT1-1 and RAR1 as signals in the Rx4-mediated HR. This discovery represents a step forward in our understanding of the mechanism of resistance to bacterial spot in tomato and may have important implications for understanding plant-bacterial interactions.
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Affiliation(s)
- Xiaofei Zhang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Ning Li
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Xin Liu
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Jiajing Wang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Yaxian Zhang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Dong Liu
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Yuqing Wang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
| | - Haipeng Cao
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
| | - Baimei Zhao
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
| | - Wencai Yang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, China Agricultural University, Beijing, 100193, China
- Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education of the People's Republic of China, Beijing, 100193, China
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46
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Tyagi S, Kumar R, Kumar V, Won SY, Shukla P. Engineering disease resistant plants through CRISPR-Cas9 technology. GM CROPS & FOOD 2021; 12:125-144. [PMID: 33079628 PMCID: PMC7583490 DOI: 10.1080/21645698.2020.1831729] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 09/13/2020] [Accepted: 09/27/2020] [Indexed: 01/08/2023]
Abstract
Plants are susceptible to phytopathogens, including bacteria, fungi, and viruses, which cause colossal financial shortfalls (pre- and post-harvest) and threaten global food safety. To combat with these phytopathogens, plant possesses two-layer of defense in the form of PAMP-triggered immunity (PTI), or Effectors-triggered immunity (ETI). The understanding of plant-molecular interactions and revolution of high-throughput molecular techniques have opened the door for innovations in developing pathogen-resistant plants. In this context, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) has transformed genome editing (GE) technology and being harnessed for altering the traits. Here we have summarized the complexities of plant immune system and the use of CRISPR-Cas9 to edit the various components of plant immune system to acquire long-lasting resistance in plants against phytopathogens. This review also sheds the light on the limitations of CRISPR-Cas9 system, regulation of CRISPR-Cas9 edited crops and future prospective of this technology.
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Affiliation(s)
- Swati Tyagi
- Genomic Division, National Institute of Agriculture Science, Rural Development Administration, Jeonju, Republic of Korea
| | - Robin Kumar
- Department of Soil Science and Agricultural Chemistry, Acharya Narendra Dev University of Agriculture and Technology, Kumarganj, Ayodhya, India
- Department of Agriculture Engineering, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, India
| | - Vivak Kumar
- Department of Agriculture Engineering, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, India
| | - So Youn Won
- Genomic Division, National Institute of Agriculture Science, Rural Development Administration, Jeonju, Republic of Korea
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
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Abstract
Population genomics is transforming our understanding of pathogen biology and evolution, and contributing to the prevention and management of disease in diverse crops. We provide an overview of key methods in bacterial population genomics and describe recent work focusing on three topics of critical importance to plant pathology: (i) resolving pathogen origins and transmission pathways during outbreak events, (ii) identifying the genetic basis of host specificity and virulence, and (iii) understanding how pathogens evolve in response to changing agricultural practices.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Christina Straub
- Institute of Environmental Science and Research, Health and Environment, Auckland, New Zealand
- Genomics Aotearoa, New Zealand
| | - Elena Colombi
- Curtin Health Innovation Research Institute (CHIRI), Curtin University, Perth, Western Australia, Australia
- School of Pharmacy and Biomedical Sciences, Curtin University, Perth, Western Australia, Australia
| | - Honour C McCann
- New Zealand Institute for Advanced Study, Massey University, Albany, New Zealand
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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Fatty Acids from Hermetia illucens Larvae Fat Inhibit the Proliferation and Growth of Actual Phytopathogens. Microorganisms 2020; 8:microorganisms8091423. [PMID: 32948050 PMCID: PMC7563668 DOI: 10.3390/microorganisms8091423] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/03/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023] Open
Abstract
The rapid increase of plant diseases caused by bacterial phytopathogens calls for an urgent search for new antibacterials. Antimicrobial compounds of natural origin stand up as frontiers in the attempts of the antibiotic overuse replacement. With this in mind, the Hermetia illucens (H. illucens) larvae have recently gained attention as a promising approach to fulfill this need. This study aimed to isolate the active constituents of H. illucens larvae fat and to estimate its antimicrobial capacity. We discovered the best composition of extracting solution retaining the pronounced antimicrobial activity of the extract. Using gas chromatography-mass spectrometry (GC-MS), we identified the unique natural array of fatty acids as the major constituents of the acidified water-methanol extract (AWME) as having new antimicrobial potency. In standard turbidimetric assay, the minimum inhibitory concentration (MIC) of the AWME was 0.78 mg/mL after 24 h of incubation for all five tested phytopathogenic bacteria strains: Pantoea agglomerans, Xanthomonas campestris, Pectobacterium carotovorum subsp. carotovorum, Pectobacterium atrosepticum, and Dickeya solani. The minimum bactericidal concentration (MBC) ranged from 0.78 to 1.56 mg/mL against all tested strains after 24 h of incubation. The inhibition zone size of AWME (INZ) at 50 mg/mL concentration was in the range 12.2 ± 0.56 to 19.0 ± 0.28 mm, while zone size for the positive control (penicillin-streptomycin) (5000 IU/mL-5000 µg/mL) was in the scale of 20.63 ± 0.53 to 24.0 ± 0.35 mm as revealed by standard disk diffusion assay. For the first time, our findings indicated the substantial antibacterial potential of AWME of H. illucens larvae fat against these actual phytopathogens, thus paving the way for further research to determine the mechanism of action in crop protection.
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49
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Timilsina S, Potnis N, Newberry EA, Liyanapathiranage P, Iruegas-Bocardo F, White FF, Goss EM, Jones JB. Xanthomonas diversity, virulence and plant-pathogen interactions. Nat Rev Microbiol 2020; 18:415-427. [PMID: 32346148 DOI: 10.1038/s41579-020-0361-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
Xanthomonas spp. encompass a wide range of plant pathogens that use numerous virulence factors for pathogenicity and fitness in plant hosts. In this Review, we examine recent insights into host-pathogen co-evolution, diversity in Xanthomonas populations and host specificity of Xanthomonas spp. that have substantially improved our fundamental understanding of pathogen biology. We emphasize the virulence factors in xanthomonads, such as type III secreted effectors including transcription activator-like effectors, type II secretion systems, diversity resulting in host specificity, evolution of emerging strains, activation of susceptibility genes and strategies of host evasion. We summarize the genomic diversity in several Xanthomonas spp. and implications for disease outbreaks, management strategies and breeding for disease resistance.
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Affiliation(s)
- Sujan Timilsina
- Plant Pathology Department, University of Florida, Gainesville, FL, USA
| | - Neha Potnis
- Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Eric A Newberry
- Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | | | | | - Frank F White
- Plant Pathology Department, University of Florida, Gainesville, FL, USA
| | - Erica M Goss
- Plant Pathology Department, University of Florida, Gainesville, FL, USA. .,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
| | - Jeffrey B Jones
- Plant Pathology Department, University of Florida, Gainesville, FL, USA.
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50
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Thomas NC, Hendrich CG, Gill US, Allen C, Hutton SF, Schultink A. The Immune Receptor Roq1 Confers Resistance to the Bacterial Pathogens Xanthomonas, Pseudomonas syringae, and Ralstonia in Tomato. FRONTIERS IN PLANT SCIENCE 2020; 11:463. [PMID: 32391034 PMCID: PMC7192161 DOI: 10.3389/fpls.2020.00463] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 03/30/2020] [Indexed: 05/22/2023]
Abstract
Xanthomonas species, Pseudomonas syringae and Ralstonia species are bacterial plant pathogens that cause significant yield loss in many crop species. Generating disease-resistant crop varieties can provide a more sustainable solution to control yield loss compared to chemical methods. Plant immune receptors encoded by nucleotide-binding, leucine-rich repeat (NLR) genes typically confer resistance to pathogens that produce a cognate elicitor, often an effector protein secreted by the pathogen to promote virulence. The diverse sequence and presence/absence variation of pathogen effector proteins within and between pathogen species usually limits the utility of a single NLR gene to protecting a plant from a single pathogen species or particular strains. The NLR protein Recognition of XopQ 1 (Roq1) was recently identified from the plant Nicotiana benthamiana and mediates perception of the effector proteins XopQ and HopQ1 from Xanthomonas and P. syringae respectively. Unlike most recognized effectors, alleles of XopQ/HopQ1 are highly conserved and present in most plant pathogenic strains of Xanthomonas and P. syringae. A homolog of XopQ/HopQ1, named RipB, is present in most Ralstonia strains. We found that Roq1 confers immunity to Xanthomonas, P. syringae, and Ralstonia when expressed in tomato. Strong resistance to Xanthomonas perforans was observed in three seasons of field trials with both natural and artificial inoculation. The Roq1 gene can therefore be used to provide safe, economical, and effective control of these pathogens in tomato and other crop species and reduce or eliminate the need for traditional chemical controls.
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Affiliation(s)
- Nicholas C. Thomas
- Fortiphyte Inc., Berkeley, CA, United States
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Connor G. Hendrich
- Department of Plant Pathology, University of Wisconsin–Madison, Madison, WI, United States
| | - Upinder S. Gill
- IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin–Madison, Madison, WI, United States
| | - Samuel F. Hutton
- IFAS, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States
| | - Alex Schultink
- Fortiphyte Inc., Berkeley, CA, United States
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, United States
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