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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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2
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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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Liyanapathiranage P, Jones JB, Potnis N. Mutation of a Single Core Gene, tssM, of Type VI Secretion System of Xanthomonas perforans Influences Virulence, Epiphytic Survival, and Transmission During Pathogenesis on Tomato. PHYTOPATHOLOGY 2022; 112:752-764. [PMID: 34543058 DOI: 10.1094/phyto-02-21-0069-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Xanthomonas perforans is a seedborne hemibiotrophic pathogen that successfully establishes infection in the phyllosphere of tomato. While most studies investigating mechanistic basis of pathogenesis have focused on successful apoplastic growth, factors important during asymptomatic colonization in the early stages of disease development are not well understood. In this study, we show that tssM gene of the type VI secretion system cluster i3* (T6SS-i3*) plays a significant role during initial asymptomatic epiphytic colonization at different stages during the life cycle of the pathogen. Mutation in a core gene, tssM of T6SS-i3*, imparted higher aggressiveness to the pathogen, as indicated by higher overall disease severity, higher in planta growth, and shorter latent infection period compared with the wild-type upon dip inoculation of 4- to 5-week-old tomato plants. Contribution of tssM toward aggressiveness was evident during vertical transmission from seed to seedling, with wild-type showing reduced disease severity as well as lower in planta populations on seedlings compared with the mutant. Presence of functional TssM offered higher epiphytic fitness as well as higher dissemination potential to the pathogen when tested in an experimental setup mimicking transplant house high-humidity conditions. We showed higher osmotolerance being one mechanism by which TssM offers higher epiphytic fitness. Taken together, these data reveal that functional TssM plays a larger role in offering ecological advantage to the pathogen. TssM prolongs the association of hemibiotrophic pathogen with the host, minimizing overall disease severity yet facilitating successful dissemination.
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Affiliation(s)
| | - 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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Luneau JS, Cerutti A, Roux B, Carrère S, Jardinaud M, Gaillac A, Gris C, Lauber E, Berthomé R, Arlat M, Boulanger A, Noël LD. Xanthomonas transcriptome inside cauliflower hydathodes reveals bacterial virulence strategies and physiological adaptations at early infection stages. MOLECULAR PLANT PATHOLOGY 2022; 23:159-174. [PMID: 34837293 PMCID: PMC8743013 DOI: 10.1111/mpp.13117] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/22/2021] [Accepted: 07/22/2021] [Indexed: 06/01/2023]
Abstract
Xanthomonas campestris pv. campestris (Xcc) is a seed-transmitted vascular pathogen causing black rot disease on cultivated and wild Brassicaceae. Xcc enters the plant tissues preferentially via hydathodes, which are organs localized at leaf margins. To decipher both physiological and virulence strategies deployed by Xcc during early stages of infection, the transcriptomic profile of Xcc was analysed 3 days after entry into cauliflower hydathodes. Despite the absence of visible plant tissue alterations and despite a biotrophic lifestyle, 18% of Xcc genes were differentially expressed, including a striking repression of chemotaxis and motility functions. The Xcc full repertoire of virulence factors had not yet been activated but the expression of the HrpG regulon composed of 95 genes, including genes coding for the type III secretion machinery important for suppression of plant immunity, was induced. The expression of genes involved in metabolic adaptations such as catabolism of plant compounds, transport functions, sulphur and phosphate metabolism was upregulated while limited stress responses were observed 3 days postinfection. We confirmed experimentally that high-affinity phosphate transport is needed for bacterial fitness inside hydathodes. This analysis provides information about the nutritional and stress status of bacteria during the early biotrophic infection stages and helps to decipher the adaptive strategy of Xcc to the hydathode environment.
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Affiliation(s)
- Julien S. Luneau
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Aude Cerutti
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Brice Roux
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
- Present address:
Brice Roux, HalioDx, Luminy Biotech EntreprisesMarseille Cedex 9France
| | - Sébastien Carrère
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | | | - Antoine Gaillac
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Carine Gris
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Emmanuelle Lauber
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Richard Berthomé
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Matthieu Arlat
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Alice Boulanger
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
| | - Laurent D. Noël
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul SabatierCastanet‐TolosanFrance
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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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6
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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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7
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Soldan R, Fusi M, Cardinale M, Daffonchio D, Preston GM. The effect of plant domestication on host control of the microbiota. Commun Biol 2021; 4:936. [PMID: 34354230 PMCID: PMC8342519 DOI: 10.1038/s42003-021-02467-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 07/16/2021] [Indexed: 02/07/2023] Open
Abstract
Macroorganisms are colonized by microbial communities that exert important biological and ecological functions, the composition of which is subject to host control and has therefore been described as "an ecosystem on a leash". However, domesticated organisms such as crop plants are subject to both artificial selection and natural selection exerted by the agricultural ecosystem. Here, we propose a framework for understanding how host control of the microbiota is influenced by domestication, in which a double leash acts from domesticator to host and host to microbes. We discuss how this framework applies to a plant compartment that has demonstrated remarkable phenotypic changes during domestication: the seed.
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Affiliation(s)
- Riccardo Soldan
- University of Oxford, Department of Plant Sciences, Oxford, UK.
| | - Marco Fusi
- Edinburgh Napier University, School of Applied Sciences, Edinburgh, UK
| | - Massimiliano Cardinale
- University of Salento, Department of Biological and Environmental Sciences and Technologies, Lecce, Italy
| | - Daniele Daffonchio
- King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, Saudi Arabia
| | - Gail M Preston
- University of Oxford, Department of Plant Sciences, Oxford, UK.
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8
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Burris KP, Simmons OD, Webb HM, Moore RG, Jaykus LA, Zheng J, Reed E, Ferreira CM, Brown E, Bell RL. Salmonella enterica colonization and fitness in pre-harvest cantaloupe production. Food Microbiol 2020; 93:103612. [PMID: 32912584 DOI: 10.1016/j.fm.2020.103612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/14/2020] [Accepted: 07/29/2020] [Indexed: 11/25/2022]
Abstract
Cantaloupes have emerged as significant vehicles of widespread foodborne illness outbreaks caused by bacterial pathogens, including Salmonella. The purpose of this study was to investigate the efficiency of Salmonella colonization and internalization in cantaloupes by relevant routes of contamination. Cantaloupe plants (Cucumis melo 'reticulatus') from two cultivars 'Athena' (Eastern) and 'Primo' (Western) were grown from commercial seed. Plants were maintained in the NCSU BSL-3P phytotron greenhouse. Salmonella enterica (a cocktail of cantaloupe-associated outbreak serovars Javiana, Newport, Panama, Poona and Typhimurium) contamination was introduced via blossoms or soil at ca. 4.4 log10 CFU/blossom or 8.4 log10 CFU/root zone, respectively. Cantaloupes were analyzed for Salmonella by enrichment in accordance with modified FDA-BAM methods. Five randomly chosen colonies from each Salmonella-positive sample were typed using the Agilent 2100 bioanalyzer following multiplex PCR. Data were analyzed for prevalence of contamination and serovar predominance in fruit, stems and soil. Of the total cantaloupe fruit harvested from Salmonella-inoculated blossoms (n = 63), 89% (56/63) were externally contaminated and 73% (46/63) had Salmonella internalized into the fruit. Serovar Panama was the most commonly isolated from the surface of fruit while S. Panama and S. Poona were the most prevalent inside the fruit. When soil was inoculated with Salmonella at one day post-transplant, 13% (8/60) of the plants were shown to translocate the organism to the lower stem (ca. 4 cm) by 7 days post-inoculation (dpi). We observed Salmonella persistence in the soil up to 60 dpi with S. Newport being the predominant serovar at 10 and 20 dpi. These data demonstrate that contaminated soil and blossoms can lead to Salmonella internalization into the plant or fruit at a relatively high frequency.
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Affiliation(s)
- Kellie P Burris
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA; Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA.
| | - Otto D Simmons
- Department of Horticultural Science, North Carolina State University, Raleigh, NC, USA
| | - Hannah M Webb
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Robin Grant Moore
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Lee-Ann Jaykus
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Jie Zheng
- Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA
| | - Elizabeth Reed
- Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA
| | - Christina M Ferreira
- Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA
| | - Eric Brown
- Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA
| | - Rebecca L Bell
- Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, College Park, MD, USA
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Burris KP, Simmons OD, Webb HM, Deese LM, Moore RG, Jaykus LA, Zheng J, Reed E, Ferreira CM, Brown EW, Bell RL. Colonization and Internalization of Salmonella enterica and Its Prevalence in Cucumber Plants. Front Microbiol 2020; 11:1135. [PMID: 32547530 PMCID: PMC7273826 DOI: 10.3389/fmicb.2020.01135] [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: 01/05/2020] [Accepted: 05/05/2020] [Indexed: 11/21/2022] Open
Abstract
Consumption of cucumbers (Cucumis sativus var. sativus) has been linked to several foodborne outbreaks involving Salmonella enterica. The purpose of this work was to investigate the efficiency of colonization and internalization of S. enterica into cucumber plants by various routes of contamination. Produce-associated outbreak strains of Salmonella (a cocktail of serovars Javiana, Montevideo, Newport, Poona, and Typhimurium) were introduced to three cultivars of cucumber plants (two slicing cultivars and one pickling) via blossoms (ca. 6.4 log10 CFU/blossom, 4.5 log10 CFU/blossom, or 2.5 log10 CFU/blossom) or soil (ca. 8.3 log10 CFU/root zone) and were analyzed for prevalence of Salmonella contamination (internal and external) and serovar predominance in fruit and stems. Of the total slicing fruit harvested from Salmonella-inoculated blossoms (ca. 6.4, 4.5, or 2.5 log10 CFU/blossom), 83.9% (47/56), 81.4% (48/59) or 71.2% (84/118) were found colonized and 67.9% (38/56), 35.6% (21/59) or 22.0% (26/118) had Salmonella internalized into the fruit, respectively. S. Poona was the most prevalent serovar isolated on or in cucumber fruits at all inoculation levels. When soil was inoculated at 1 day post-transplant (dpt), 8% (10/120) of the plants were shown to translocate Salmonella to the lower stem 7 days post-inoculation (dpi). Results identified blossoms as an important route by which Salmonella internalized at a high percentage into cucumbers, and S. Poona, the same strain isolated from the 2015 outbreak of cucumbers imported from Mexico, was shown to be well-adapted to the blossom niche.
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Affiliation(s)
- Kellie P. Burris
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, United States
| | - Otto D. Simmons
- Department of Horticultural Science, North Carolina State University, Raleigh, NC, United States
| | - Hannah M. Webb
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, United States
| | - Lauren M. Deese
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, United States
| | - Robin Grant Moore
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, United States
| | - Lee-Ann Jaykus
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, United States
| | - Jie Zheng
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States
| | - Elizabeth Reed
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States
| | - Christina M. Ferreira
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States
| | - Eric W. Brown
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States
| | - Rebecca L. Bell
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States
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10
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Multiplex real-time PCR for the detection of Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato and pathogenic Xanthomonas species on tomato plants. PLoS One 2020; 15:e0227559. [PMID: 31910230 PMCID: PMC6946519 DOI: 10.1371/journal.pone.0227559] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 12/20/2019] [Indexed: 01/08/2023] Open
Abstract
A multiplex real-time PCR method based on fluorescent TaqMan® probes was developed for the simultaneous detection of the tomato pathogenic bacteria Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato and bacterial spot-causing xanthomonads. The specificity of the multiplex assay was validated on 44 bacterial strains, including 32 target pathogen strains as well as closely related species and nontarget tomato pathogenic bacteria. The designed multiplex real-time PCR showed high sensitivity when positive amplification was observed for one pg of bacterial DNA in the cases of Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato bacteria and 100 pg for bacterial spot-causing xanthomonads. The reliability of the developed multiplex real-time PCR assay for in planta detection was verified by recognition of the target pathogens in 18 tomato plants artificially inoculated by each of the target bacteria and tomato samples from production greenhouses.
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11
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Dutta B, Langston DB, Luo X, Carlson S, Kichler J, Gitaitis R. A Risk Assessment Model for Bacterial Leaf Spot of Pepper (Capsicum annuum), Caused by Xanthomonas euvesicatoria, Based on Concentrations of Macronutrients, Micronutrients, and Micronutrient Ratios. PHYTOPATHOLOGY 2017; 107:1331-1338. [PMID: 28686086 DOI: 10.1094/phyto-05-17-0187-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The phytopathogenic bacterium Xanthomonas euvesicatoria causes bacterial leaf spot (BLS) of pepper and has a worldwide distribution. BLS is difficult to control and an integrated management strategy that incorporates crop rotation, use of clean seed and clean plants, weed control, resistant varieties, applications of bactericides, biocontrol agents, and systemic acquired resistance (SAR) inducers is generally recommended. However, even with that arsenal of weapons, BLS can still be responsible for severe losses under favorable environmental conditions. Thus, additional tools need to be added to an overall integrated management strategy to combat BLS. In this article, we developed several models from 2012 to 2014 that were based on how macronutrients, micronutrients, and micronutrient ratios affect BLS severity. Factors used to select a model for validation included highly significant P values, high adjusted R2 values, low variance inflation factor values (<5), root mean square error, Mallow's Cp, and high Akaike's information criterion correction values. In addition, salicylic acid (SA) concentrations and relative expression of nonexpresser pathogenesis-related gene1 (NPR1) and pathogenesis-related protein 1 (PR1) in pepper tissues were also considered in model selection. A model (ECGA1) consisting of concentrations of copper, manganese, potassium, and the iron/zinc ratio as independent variables was used for validation in three different commercial pepper fields in Georgia: Colquitt County and Worth County in 2015 and Tift County in 2016. When area under the disease progress curve (AUDPC) values for two field sites (Colquitt and Worth Counties) in 2015 were pulled together and plotted against ECGA1-predicted values for both sites, the resulting relationship was highly significant (P = 0.0001) with an R2 value of 0.92. A significant relationship between observed AUDPC versus predicted values was also observed in Tift County in 2016 (P < 0.001; adjusted R2 = 0.98). Relative gene expression of both NPR1 and PR1 genes was significantly (P < 0.01) higher in pepper grown in predicted low-risk sites compared with pepper from high-risk sites in Colquitt, Worth, and Tift Counties. Although BLS severity will fluctuate depending on environmental conditions, the data indicate that the level of risk at a particular location may be influenced by how macronutrient and micronutrient concentrations affect plant disease resistance genes in the SAR pathway.
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Affiliation(s)
- B Dutta
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
| | - D B Langston
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
| | - X Luo
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
| | - S Carlson
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
| | - J Kichler
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
| | - R Gitaitis
- First and sixth authors: Department of Plant Pathology, University of Georgia, Tifton 31793; second author: Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk 23437; third author: Experimental Statistics, University of Georgia, Tifton; fourth author: County Extension Agent, Tift County, University of Georgia Cooperative Extension; and fifth author: County Extension Agent, Colquitt County, University of Georgia Cooperative Extension, Moultrie 31788
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Petkar A, Ji P. Infection Courts in Watermelon Plants Leading to Seed Infestation by Fusarium oxysporum f. sp. niveum. PHYTOPATHOLOGY 2017; 107:828-833. [PMID: 28414630 DOI: 10.1094/phyto-12-16-0429-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Fusarium wilt incited by Fusarium oxysporum f. sp. niveum is a seed-transmitted disease that causes significant yield loss in watermelon production. The pathogen may infect watermelon seeds latently, which can be an important inoculum source and contribute to severe disease outbreak. However, information regarding infection courts of F. oxysporum f. sp. niveum leading to infestation of watermelon seeds is limited. To determine how seeds in watermelon fruit can be infested by F. oxysporum f. sp. niveum during the watermelon growing season, greenhouse and field experiments were conducted in 2014 and 2015 where watermelon flowers and immature fruit were inoculated with F. oxysporum f. sp. niveum. Seeds were extracted from mature watermelon fruit, and infestation of watermelon seeds was determined by isolation of F. oxysporum f. sp. niveum and further confirmed by real-time polymerase chain reaction (PCR) analysis. Inoculation of the pericarp of immature fruit resulted in 17.8 to 54.4% of infested seeds under field conditions and 0.6 to 12.8% of infested seeds under greenhouse conditions when seeds were not surface disinfested prior to isolation. Seed infestation was also detected in 0 to 4.5% of the seeds when seeds were surface disinfested prior to isolation. Inoculation of pistil resulted in 0 to 7.2% and 0 to 18.3% of infested seeds under greenhouse and field conditions when seeds were surface disinfested or not disinfested before isolation, respectively. Inoculation of peduncle resulted in 0.6 to 6.1% and 0 to 10.0% of infested seeds in the greenhouse and field experiments when seeds were surface disinfested or not disinfested before isolation, respectively. Seed infestation was also detected in all the experiments using real-time PCR assay when pericarp or pistil was inoculated, and in three of four experiments when peduncle was inoculated, regardless of whether seeds were surface disinfested or not disinfested. Pericarp and peduncle of immature watermelon fruit and pistil of watermelon flowers could be potential infection courts for F. oxysporum f. sp. niveum leading to infestation of seeds in asymptomatic watermelon fruit.
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Affiliation(s)
- Aparna Petkar
- Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31794
| | - Pingsheng Ji
- Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31794
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Dutta B, Gitaitis R, Smith S, Langston D. Interactions of seedborne bacterial pathogens with host and non-host plants in relation to seed infestation and seedling transmission. PLoS One 2014; 9:e99215. [PMID: 24936863 PMCID: PMC4061015 DOI: 10.1371/journal.pone.0099215] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/12/2014] [Indexed: 11/18/2022] Open
Abstract
The ability of seed-borne bacterial pathogens (Acidovorax citrulli, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas euvesicatoria, and Pseudomonas syringae pv. glycinea) to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean) and subsequent pathogen transmission to seedlings was investigated. A non-pathogenic, pigmented strain of Serratia marcescens was also included to assess a null-interacting situation with the same plant species. Flowers of host and non-host plants were inoculated with 1 × 10(6) colony forming units (CFUs)/flower for each bacterial species and allowed to develop into fruits or umbels (in case of onion). Seeds harvested from each host/non-host bacterial species combination were assayed for respective bacteria by plating on semi-selective media. Additionally, seedlots for each host/non-host bacterial species combination were also assayed for pathogen transmission by seedling grow-out (SGO) assays under greenhouse conditions. The mean percentage of seedlots infested with compatible and incompatible pathogens was 31.7 and 30.9% (by plating), respectively and they were not significantly different (P = 0.67). The percentage of seedlots infested with null-interacting bacterial species was 16.8% (by plating) and it was significantly lower than the infested lots generated with compatible and incompatible bacterial pathogens (P = 0.03). None of the seedlots with incompatible/null-interacting bacteria developed symptoms on seedlings; however, when seedlings were assayed for epiphytic bacterial presence, 19.5 and 9.4% of the lots were positive, respectively. These results indicate that the seeds of non-host plants can become infested with incompatible and null-interacting bacterial species through flower colonization and they can be transmitted via epiphytic colonization of seedlings. In addition, it was also observed that flowers and seeds of non-host plants can be colonized by compatible/incompatible/null-interacting bacteria to higher populations; however, the level of colonization differed significantly depending on the type of bacterial species used.
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Affiliation(s)
- Bhabesh Dutta
- Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton, Georgia, United States of America
| | - Ronald Gitaitis
- Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton, Georgia, United States of America
| | - Samuel Smith
- Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton, Georgia, United States of America
| | - David Langston
- Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton, Georgia, United States of America
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