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Zuo S, Xu L, Zhang H, Jiang M, Wu S, Zhang LH, Zhou X, Wang J. FlgI Is a Sec-Dependent Effector of Candidatus Liberibacter asiaticus That Can Be Blocked by Small Molecules Identified Using a Yeast Screen. PLANTS (BASEL, SWITZERLAND) 2024; 13:318. [PMID: 38276775 PMCID: PMC10819201 DOI: 10.3390/plants13020318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas) is considered to be the main pathogen responsible for HLB. There is currently no effective practical strategy for the control of HLB. Our understanding of how pathogens cause HLB is limited because CLas has not been artificially cultured. In this study, 15 potential virulence factors were predicted from the proteome of CLas through DeepVF and PHI-base searches. One among them, FlgI, was found to inhibit yeast growth when expressed in Saccharomyces cerevisiae. The expression of the signal peptide of FlgI fused with PhoA in Escherichia coli resulted in the discovery that FlgI was a novel Sec-dependent secretory protein. We further found that the carboxyl-terminal HA-tagged FlgI was secreted via outer membrane vesicles in Sinorhizobium meliloti. Fluoresence localization of transient expression FlgI-GFP in Nicotiana benthamiana revealed that FlgI is mainly localized in the cytoplasm, cell periphery, and nuclear periphery of tobacco cells. In addition, our experimental results suggest that FlgI has a strong ability to induce callose deposition and cell necrosis in N. benthamiana. Finally, by screening a large library of compounds in a high-throughput format, we found that cyclosporin A restored the growth of FlgI-expressing yeast. These results confirm that FlgI is a novel Sec-dependent effector, enriching our understanding of CLas pathogenicity and helping to develop new and more effective strategies to manage HLB.
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Affiliation(s)
| | | | | | | | | | | | - Xiaofan Zhou
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (S.Z.); (L.X.); (H.Z.); (M.J.); (S.W.); (L.-H.Z.)
| | - Junxia Wang
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (S.Z.); (L.X.); (H.Z.); (M.J.); (S.W.); (L.-H.Z.)
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2
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Pandey SS, Xu J, Achor DS, Li J, Wang N. Microscopic and Transcriptomic Analyses of Early Events Triggered by ' Candidatus Liberibacter asiaticus' in Young Flushes of Huanglongbing-Positive Citrus Trees. PHYTOPATHOLOGY 2023; 113:985-997. [PMID: 36449527 DOI: 10.1094/phyto-10-22-0360-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: 06/17/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas) is associated with the devastating citrus disease Huanglongbing (HLB). Young flushes are the center of the HLB pathosystem due to their roles in the psyllid life cycle and in the acquisition and transmission of CLas. However, the early events of CLas infection and how CLas modulates young flush physiology remain poorly understood. Here, transmission electron microscopy analysis showed that the mean diameter of the sieve pores decreased in young leaves of HLB-positive trees after CLas infection, consistent with CLas-triggered callose deposition. RNA-seq-based global expression analysis of young leaves of HLB-positive sweet orange with (CLas-Pos) and without (CLas-Neg) detectable CLas demonstrated a significant impact on gene expression in young leaves, including on the expression of genes involved in host immunity, stress response, and plant hormone biosynthesis and signaling. CLas-Pos and CLas-Neg expression data displayed distinct patterns. The number of upregulated genes was higher than that of the downregulated genes in CLas-Pos for plant-pathogen interactions, glutathione metabolism, peroxisome, and calcium signaling, which are commonly associated with pathogen infections, compared with the healthy control. On the contrary, the number of upregulated genes was lower than that of the downregulated genes in CLas-Neg for genes involved in plant-pathogen interactions and peroxisome biogenesis/metabolism. Additionally, a time-course quantitative reverse transcription-PCR-based expression analysis visualized the induced expression of companion cell-specific genes, phloem protein 2 genes, and sucrose transport genes in young flushes triggered by CLas. This study advances our understanding of early events during CLas infection of citrus young flushes.
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Affiliation(s)
- Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Diann S Achor
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
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3
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Higgins SA, Mann M, Heck M. Strain Tracking of ' Candidatus Liberibacter asiaticus', the Citrus Greening Pathogen, by High-Resolution Microbiome Analysis of Asian Citrus Psyllids. PHYTOPATHOLOGY 2022; 112:2273-2287. [PMID: 35678589 DOI: 10.1094/phyto-02-22-0067-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The Asian citrus psyllid, Diaphorina citri, is an invasive insect and a vector of 'Candidatus Liberibacter asiaticus' (CLas), a bacterium whose growth in Citrus species results in huanglongbing (HLB), also known as citrus greening disease. Methods to enrich and sequence CLas from D. citri often rely on biased genome amplification and nevertheless contain significant quantities of host DNA. To overcome these hurdles, we developed a simple pretreatment DNase and filtration (PDF) protocol to remove host DNA and directly sequence CLas and the complete, primarily uncultivable microbiome from D. citri adults. The PDF protocol yielded CLas abundances upward of 60% and facilitated direct measurement of CLas and endosymbiont replication rates in psyllids. The PDF protocol confirmed our lab strains derived from a progenitor Florida CLas strain and accumulated 156 genetic variants, underscoring the utility of this method for bacterial strain tracking. CLas genetic polymorphisms arising in lab-reared psyllid populations included prophage-encoding regions with key functions in CLas pathogenesis, putative antibiotic resistance loci, and a single secreted effector. These variants suggest that laboratory propagation of CLas could result in different phenotypic trajectories among laboratories and could confound CLas physiology or therapeutic design and evaluation if these differences remain undocumented. Finally, we obtained genetic signatures affiliated with Citrus nuclear and organellar genomes, entomopathogenic fungal mitochondria, and commensal bacteria from laboratory-reared and field-collected D. citri adults. Hence, the PDF protocol can directly inform agricultural management strategies related to bacterial strain tracking, insect microbiome surveillance, and antibiotic resistance screening.
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Affiliation(s)
- Steven A Higgins
- Emerging Pests and Pathogens Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Ithaca, NY 14853
| | - Marina Mann
- Plant Pathology and Plant Microbe Biology Department, Cornell University, Ithaca, NY 14853
| | - Michelle Heck
- Emerging Pests and Pathogens Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Ithaca, NY 14853
- Plant Pathology and Plant Microbe Biology Department, Cornell University, Ithaca, NY 14853
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4
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Cai Q, Liu C, Yuan M, Pan L, Yang Q, Zhou L. HLB induce changes in the tree physiology of citron ( Citrus medica L. var. sarcodactylis Swingle). PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2022; 28:517-531. [PMID: 35400879 PMCID: PMC8943090 DOI: 10.1007/s12298-022-01129-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/22/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
UNLABELLED Huanglongbing (HLB) is a highly destructive disease that decreases the yield and quality of Citrus medica L. var. sarcodactylis Swingle (C. medica var. sarcodactylis) and poses a great threat to the development of the global citrus industry. To explore the influence of HLB infection on C. medica var. sarcodactylis, levels of photosynthetic pigments, malondialdehyde (MDA), and carbohydrates, as well as antioxidant enzyme activities, were measured. The results show that HLB infection decreased photosynthetic pigment content, increased MDA content and antioxidant enzyme activities, and caused various changes in carbohydrate levels in stem, fruit, and leaf tissues. Transcriptomic analysis of C. medica var. sarcodactylis was also used to identify key genes related to the carbohydrate metabolic synthesis pathway in C. medica var. sarcodactylis. The C. medica var. sarcodactylis ADP-glucose pyrophosphorylase1 (CmAGP1), CmAGP2, C. medica var. sarcodactylis Granule-bound starch synthase (CmGBSS), C. medica var. sarcodactylis Sucrose synthases1 (CmSUS1), CmSUS2, C. medica var. sarcodactylis Sucrose phosphate synthase (CmSPS), C. medica var. sarcodactylis alkaline/neutral invertase1 (CmNi1), CmNi2, CmNi3 and CmNi4 were successfully cloned and identified, and differential expression analysis showed that HLB infection significantly upregulated these genes in stems and leaves. In conclusion, HLB infection causes cellular damage, a reduction in photosynthetic capacity, decreased pathogen resistance, and severe disorders in carbohydrate metabolism in C. medica var. sarcodactylis. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s12298-022-01129-z.
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Affiliation(s)
- Qizhong Cai
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangdong Provincial Research Center On Good Agricultural Practice and Comprehensive Agricultural Development Engineering Technology of Cantonese Medicinal Materials, Comprehensive Experimental Station of Guangzhou, Chinese Material Medica, China Agriculture Research System (CARS-21-16), Key Laboratory of State Administration of Traditional Chinese Medicine for Production & Development of Cantonese Medicinal Materials, Guangzhou, 510006 China
| | - Changzheng Liu
- State Key Laboratory Breeding Base of Dao-Di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700 China
| | - Meng Yuan
- Shanting District Healthealth Bureau, Zaozhuang, 277299 China
| | - Liming Pan
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangdong Provincial Research Center On Good Agricultural Practice and Comprehensive Agricultural Development Engineering Technology of Cantonese Medicinal Materials, Comprehensive Experimental Station of Guangzhou, Chinese Material Medica, China Agriculture Research System (CARS-21-16), Key Laboratory of State Administration of Traditional Chinese Medicine for Production & Development of Cantonese Medicinal Materials, Guangzhou, 510006 China
| | - Quan Yang
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangdong Provincial Research Center On Good Agricultural Practice and Comprehensive Agricultural Development Engineering Technology of Cantonese Medicinal Materials, Comprehensive Experimental Station of Guangzhou, Chinese Material Medica, China Agriculture Research System (CARS-21-16), Key Laboratory of State Administration of Traditional Chinese Medicine for Production & Development of Cantonese Medicinal Materials, Guangzhou, 510006 China
| | - Liangyun Zhou
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangdong Provincial Research Center On Good Agricultural Practice and Comprehensive Agricultural Development Engineering Technology of Cantonese Medicinal Materials, Comprehensive Experimental Station of Guangzhou, Chinese Material Medica, China Agriculture Research System (CARS-21-16), Key Laboratory of State Administration of Traditional Chinese Medicine for Production & Development of Cantonese Medicinal Materials, Guangzhou, 510006 China
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Ibanez F, Suh JH, Wang Y, Rivera M, Setamou M, Stelinski LL. Salicylic acid mediated immune response of Citrus sinensis to varying frequencies of herbivory and pathogen inoculation. BMC PLANT BIOLOGY 2022; 22:7. [PMID: 34979915 PMCID: PMC8722004 DOI: 10.1186/s12870-021-03389-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/08/2021] [Indexed: 05/07/2023]
Abstract
BACKGROUND Plant immunity against pathogens and pests is comprised of complex mechanisms orchestrated by signaling pathways regulated by plant hormones [Salicylic acid (SA) and Jasmonic acid (JA)]. Investigations of plant immune response to phytopathogens and phloem-feeders have revealed that SA plays a critical role in reprogramming of the activity and/or localization of transcriptional regulators via post-translational modifications. We explored the contributing effects of herbivory by a phytopathogen vector [Asian citrus psyllid, Diaphorina citri] and pathogen [Candidatus Liberibacter asiaticus (CaLas)] infection on response of sweet orange [Citrus sinensis (L.) Osbeck] using manipulative treatments designed to mimic the types of infestations/infections that citrus growers experience when cultivating citrus in the face of Huanglongbing (HLB) disease. RESULTS A one-time (7 days) inoculation access period with CaLas-infected vectors caused SA-associated upregulation of PR-1, stimulating defense response after a long period of infection without herbivory (270 and 360 days). In contrast, while repeated (monthly) 'pulses' of 7 day feeding injury by psyllids stimulated immunity in CaLas-infected citrus by increasing SA in leaves initially (up to 120 days), long-term (270 and 360 days) repeated herbivory caused SA to decrease coincident with upregulation of genes associated with SA metabolism (BMST and DMR6). Similarly, transcriptional responses and metabolite (SA and its analytes) accumulation in citrus leaves exposed to a continuously reproducing population of D. citri exhibited a transitory upregulation of genes associated with SA signaling at 120 days and a posterior downregulation after long-term psyllid (adults and nymphs) feeding (270 and 360 days). CONCLUSIONS Herbivory played an important role in regulation of SA accumulation in mature leaves of C. sinensis, whether or not those trees were coincidentally infected with CaLas. Our results indicate that prevention of feeding injury inflicted by D. citri from the tritrophic interaction may allow citrus plants to better cope with the consequences of CaLas infection, highlighting the importance of vector suppression as a component of managing this cosmopolitan disease.
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Affiliation(s)
- Freddy Ibanez
- Department of Entomology and Nematology, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, 33850 USA
- Present address: Texas A&M University-AgriLife Research, 2415 E Highway 83 –, Weslaco, TX 78596 USA
| | - Joon Hyuk Suh
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, 33850 USA
| | - Yu Wang
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, 33850 USA
| | - Monique Rivera
- Department of Entomology, University of California Riverside, Riverside, California, 92521 USA
| | - Mamoudou Setamou
- Texas A&M University-Kingsville Citrus Center, 312 N International Blvd, Weslaco, TX 78599 USA
| | - Lukasz L. Stelinski
- Department of Entomology and Nematology, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, 33850 USA
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6
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Vasconcelos FNC, Li J, Pang Z, Vincent C, Wang N. The Total Population Size of ' Candidatus Liberibacter asiaticus' Inside the Phloem of Citrus Trees and the Corresponding Metabolic Burden Related to Huanglongbing Disease Development. PHYTOPATHOLOGY 2021; 111:1122-1128. [PMID: 33090080 DOI: 10.1094/phyto-09-20-0388-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas) is the predominant causal agent of citrus huanglongbing, the most devastating citrus disease worldwide. CLas colonizes phloem tissue and causes phloem dysfunction. The pathogen population size in local tissues and in the whole plant is critical for the development of disease symptoms by determining the load of pathogenicity factors and metabolic burden to the host. However, the total population size of CLas in a whole plant and the ratio of CLas to citrus cells in local tissues have not been addressed previously. The total CLas population size for 2.5-year-old 'Valencia' sweet orange on 'Kuharske' citrange rootstock trees was quantified using quantitative PCR to be approximately 1.74 × 109 cells/tree, whereas 7- and 20-year-old sweet orange trees were estimated to be 4.3 × 1010 cells/tree, and 6.0 × 1010 cells/tree, respectively. The majority of CLas cells were distributed in leaf tissues (55.58%), followed by those in branch (36.78%), feeder root (4.75%), trunk (2.39%), and structural root (0.51%) tissues. The ratios of citrus cells to CLas cells for branch, leaf, trunk, feeder root, and structural root samples were within approximately 39 to 79, 44 to 124, 153 to 1,355, 191 to 1,054, and 561 to 3,760, respectively, representing the metabolic burden of CLas in different organs. It was estimated that the ratios of phloem cells to CLas cells for branch, leaf, trunk, feeder root, and structural root samples are approximately 0.39 to 0.79, 0.44 to 1.24, 1.53 to 13.55, 1.91 to 10.54, and 5.61 to 37.60, respectively. Approximately 0.01% of the total citrus phloem volume was estimated to be occupied by CLas, explaining the difficulty to observe CLas in most tissues under transmission electron microscopy. The CLas titer inside the leaf was estimated to be approximately 1.64 × 106 cells/leaf or 9.2 × 104 cells cm-2 in leaves, approximately 104 times less than that of typical apoplastic bacterial pathogens. This study provides quantitative estimates of phloem colonization by bacterial pathogens and furthers the understanding of the biology and virulence mechanisms of CLas.
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Affiliation(s)
- Fernanda N C Vasconcelos
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Jinuyn Li
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Zhiqian Pang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Christopher Vincent
- Citrus Research and Education Center (CREC), Department of Horticultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
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7
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Liu K, He J, Guan Z, Zhong M, Pang R, Han Q. Transcriptomic and Metabolomic Analyses of Diaphorina citri Kuwayama Infected and Non-infected With Candidatus Liberibacter Asiaticus. Front Physiol 2021; 11:630037. [PMID: 33716757 PMCID: PMC7943627 DOI: 10.3389/fphys.2020.630037] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/21/2020] [Indexed: 11/13/2022] Open
Abstract
The Asian citrus psyllid Diaphorina citri is the transmission vector of Huanglongbing (HLB), a devastating disease of citrus plants. The bacterium “Candidatus Liberibacter asiaticus” (CLas) associated with HLB is transmitted between host plants by D. citri in a circulative manner. Understanding the interaction between CLas and its insect vector is key for protecting citrus cultivation from HLB damage. Here, we used RNA sequencing and liquid chromatography-mass spectrometry (LC-MS) to analyze the transcriptome and metabolome of D. citri interacting with CLas. We identified 662 upregulated and 532 downregulated genes in CLas-infected insects. These genes were enriched in pathways involving carbohydrate metabolism, the insects’ immune system, and metabolism of cofactors and vitamins. We also detected 105 differential metabolites between CLas-infected and non-infected insects, including multiple nucleosides and lipid-related molecules. The integrated analysis revealed nine pathways—including those of the glycine, serine, threonine, and purine metabolism—affected by the differentially expressed genes from both groups. The network for these pathways was subsequently constructed. Our results thus provide insights regarding the cross-talk between the transcriptomic and metabolomic changes in D. citri in response to CLas infection, as well as information on the pathways and genes/metabolites related to the CLas–D. citri interaction.
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Affiliation(s)
- Kai Liu
- College of Agriculture and Biology, Innovative Institute for Plant Health, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Jiawei He
- College of Agriculture and Biology, Innovative Institute for Plant Health, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Ziying Guan
- College of Agriculture and Biology, Innovative Institute for Plant Health, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Mingzhao Zhong
- College of Agriculture and Biology, Innovative Institute for Plant Health, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Rui Pang
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Qunxin Han
- College of Agriculture and Biology, Innovative Institute for Plant Health, Zhongkai University of Agriculture and Engineering, Guangzhou, China
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Coates LC, Mahoney J, Ramsey JS, Warwick E, Johnson R, MacCoss MJ, Krasnoff SB, Howe KJ, Moulton K, Saha S, Mueller LA, Hall DG, Shatters RG, Heck ML, Slupsky CM. Development on Citrus medica infected with 'Candidatus Liberibacter asiaticus' has sex-specific and -nonspecific impacts on adult Diaphorina citri and its endosymbionts. PLoS One 2020; 15:e0239771. [PMID: 33022020 PMCID: PMC7537882 DOI: 10.1371/journal.pone.0239771] [Citation(s) in RCA: 8] [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: 06/24/2020] [Accepted: 09/11/2020] [Indexed: 12/11/2022] Open
Abstract
Huanglongbing (HLB) is a deadly, incurable citrus disease putatively caused by the unculturable bacterium, 'Candidatus Liberibacter asiaticus' (CLas), and transmitted by Diaphorina citri. Prior studies suggest D. citri transmits CLas in a circulative and propagative manner; however, the precise interactions necessary for CLas transmission remain unknown, and the impact of insect sex on D. citri-CLas interactions is poorly understood despite reports of sex-dependent susceptibilities to CLas. We analyzed the transcriptome, proteome, metabolome, and microbiome of male and female adult D. citri reared on healthy or CLas-infected Citrus medica to determine shared and sex-specific responses of D. citri and its endosymbionts to CLas exposure. More sex-specific than shared D. citri responses to CLas were observed, despite there being no difference between males and females in CLas density or relative abundance. CLas exposure altered the abundance of proteins involved in immunity and cellular and oxidative stress in a sex-dependent manner. CLas exposure impacted cuticular proteins and enzymes involved in chitin degradation, as well as energy metabolism and abundance of the endosymbiont 'Candidatus Profftella armatura' in both sexes similarly. Notably, diaphorin, a toxic Profftella-derived metabolite, was more abundant in both sexes with CLas exposure. The responses reported here resulted from a combination of CLas colonization of D. citri as well as the effect of CLas infection on C. medica. Elucidating these impacts on D. citri and their endosymbionts contributes to our understanding of the HLB pathosystem and identifies the responses potentially critical to limiting or promoting CLas acquisition and propagation in both sexes.
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Affiliation(s)
- Laurynne C. Coates
- Department of Food Science and Technology, University of California, Davis, California, United States of America
| | - Jaclyn Mahoney
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
| | - John S. Ramsey
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
- Robert W. Holley Center for Agriculture and Health, Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Ithaca, New York, United States of America
| | - EricaRose Warwick
- Plant Pathology, University of Florida Citrus Research and Education Center, Lake Alfred, Florida, United States of America
| | - Richard Johnson
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Stuart B. Krasnoff
- Robert W. Holley Center for Agriculture and Health, Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Ithaca, New York, United States of America
| | - Kevin J. Howe
- Robert W. Holley Center for Agriculture and Health, Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Ithaca, New York, United States of America
| | - Kathy Moulton
- U.S. Horticultural Research Laboratory, Unit of Subtropical Insects and Horticulture, USDA Agricultural Research Service, Fort Pierce, Florida, United States of America
| | - Surya Saha
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
| | - Lukas A. Mueller
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
| | - David G. Hall
- U.S. Horticultural Research Laboratory, Unit of Subtropical Insects and Horticulture, USDA Agricultural Research Service, Fort Pierce, Florida, United States of America
| | - Robert G. Shatters
- U.S. Horticultural Research Laboratory, Unit of Subtropical Insects and Horticulture, USDA Agricultural Research Service, Fort Pierce, Florida, United States of America
| | - Michelle L. Heck
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
- Robert W. Holley Center for Agriculture and Health, Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Ithaca, New York, United States of America
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, United States of America
| | - Carolyn M. Slupsky
- Department of Food Science and Technology, University of California, Davis, California, United States of America
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9
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Zuñiga C, Peacock B, Liang B, McCollum G, Irigoyen SC, Tec-Campos D, Marotz C, Weng NC, Zepeda A, Vidalakis G, Mandadi KK, Borneman J, Zengler K. Linking metabolic phenotypes to pathogenic traits among "Candidatus Liberibacter asiaticus" and its hosts. NPJ Syst Biol Appl 2020; 6:24. [PMID: 32753656 PMCID: PMC7403731 DOI: 10.1038/s41540-020-00142-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/18/2020] [Indexed: 12/21/2022] Open
Abstract
Candidatus Liberibacter asiaticus (CLas) has been associated with Huanglongbing, a lethal vector-borne disease affecting citrus crops worldwide. While comparative genomics has provided preliminary insights into the metabolic capabilities of this uncultured microorganism, a comprehensive functional characterization is currently lacking. Here, we reconstructed and manually curated genome-scale metabolic models for the six CLas strains A4, FL17, gxpsy, Ishi-1, psy62, and YCPsy, in addition to a model of the closest related culturable microorganism, L. crescens BT-1. Predictions about nutrient requirements and changes in growth phenotypes of CLas were confirmed using in vitro hairy root-based assays, while the L. crescens BT-1 model was validated using cultivation assays. Host-dependent metabolic phenotypes were revealed using expression data obtained from CLas-infected citrus trees and from the CLas-harboring psyllid Diaphorina citri Kuwayama. These results identified conserved and unique metabolic traits, as well as strain-specific interactions between CLas and its hosts, laying the foundation for the development of model-driven Huanglongbing management strategies.
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Affiliation(s)
- Cristal Zuñiga
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
| | - Beth Peacock
- Department of Microbiology and Plant Pathology, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA
| | - Bo Liang
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Greg McCollum
- USDA, ARS, US Horticultural Research Laboratory, 2001 S. Rock Road, Fort Pierce, FL, 34945, USA
| | - Sonia C Irigoyen
- Texas A&M AgriLife Research and Extension Center, Texas A&M University System, Weslaco, TX, USA
| | - Diego Tec-Campos
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Campus de Ciencias Exactas e Ingenierías, Mérida, 97203, Yucatán, México
| | - Clarisse Marotz
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
| | - Nien-Chen Weng
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
| | - Alejandro Zepeda
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Campus de Ciencias Exactas e Ingenierías, Mérida, 97203, Yucatán, México
| | - Georgios Vidalakis
- Department of Microbiology and Plant Pathology, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA
| | - Kranthi K Mandadi
- Texas A&M AgriLife Research and Extension Center, Texas A&M University System, Weslaco, TX, USA
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - James Borneman
- Department of Microbiology and Plant Pathology, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA.
| | - Karsten Zengler
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA.
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093-0412, USA.
- Center for Microbiome Innovation, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0403, USA.
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10
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Wu Y, Qu M, Pu X, Lin J, Shu B. Distinct microbial communities among different tissues of citrus tree Citrus reticulata cv. Chachiensis. Sci Rep 2020; 10:6068. [PMID: 32269258 PMCID: PMC7142118 DOI: 10.1038/s41598-020-62991-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/18/2020] [Indexed: 11/17/2022] Open
Abstract
Plant microbiota colonize all organs of a plant and play crucial roles including supplying nutrients to plants, stimulating seed germination, promoting plant growth, and defending plants against biotic and abiotic stress. Because of the economic importance, interactions between citrus and microbes have been studied relatively extensively, especially citrus-pathogen interactions. However, the spatial distribution of microbial taxa in citrus trees remains under-studied. In this study, Citrus reticulata cv. Chachiensis was examined for the spatial distribution of microbes by sequencing 16S rRNA genes. More than 2.5 million sequences were obtained from 60 samples collected from soil, roots, leaves, and phloem. The dominant microbial phyla from all samples were Proteobacteria, Actinobacteria and Acidobacteria. The composition and structure of microbial communities in different samples were analyzed by PCoA, CAP, Anosim and MRPP methods. Variation in microbial species between samples were analyzed and the indicator microbes of each sample group were identified. Our results suggested that the microbial communities from different tissues varied significantly and the microenvironments of tree tissues could affect the composition of its microbial community.
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Affiliation(s)
- Yongxian Wu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Mengqiu Qu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Xinhua Pu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Jintian Lin
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China.
| | - Benshui Shu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China.
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11
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Li H, Ying X, Shang L, Redfern B, Kypraios N, Xie X, Xu F, Wang S, Zhang J, Jian H, Yu H, Lv D. Heterologous Expression of CLIBASIA_03915/CLIBASIA_04250 by Tobacco Mosaic Virus Resulted in Phloem Necrosis in the Senescent Leaves of Nicotiana benthamiana. Int J Mol Sci 2020; 21:E1414. [PMID: 32093101 PMCID: PMC7073121 DOI: 10.3390/ijms21041414] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 02/15/2020] [Accepted: 02/17/2020] [Indexed: 12/02/2022] Open
Abstract
Huanglongbing (HLB), also known as citrus greening, is the most notorious citrus disease worldwide. Candidatus Liberibacter asiaticus (CaLas) is a phloem-restricted bacterium associated with HLB. Because there is no mutant library available, the pathogenesis of CaLas is obscure. In this study, we employed tobacco mosaic virus (TMV) to express two mature secretion proteins CLIBASIA_03915 (m03915) and CLIBASIA_04250 (m04250) in Nicotiana benthamiana (N. benthamiana). Phloem necrosis was observed in the senescent leaves of N. benthamiana that expressed the two low molecular weight proteins, while no phloem necrosis was observed in the plants that expressed the control, green fluorescent protein (GFP). Additionally, no phloem necrosis was observed in the senescent leaves of N. benthamiana that expressed the null mutation of m03915 and frameshifting m04250. The subcellular localizations of m03915 and m04250 were determined by fusion with GFP using confocal microscopy. The subcellular localization of m03915 was found to be as free GFP without a nuclear localization sequence (NLS). However, m04250 did have an NLS. Yeast two-hybrid (Y2H) was carried out to probe the citrus proteins interacting with m03915 and m04250. Six citrus proteins were found to interact with m03915. The identified proteins were involved in the metabolism of compounds, transcription, response to abiotic stress, ubiquitin-mediated protein degradation, etc. The prey of m04250 was involved in the processing of specific pre-mRNAs. Identification of new virulence factors of CaLas will give insight into the pathogenesis of CaLas, and therefore, it will eventually help develop the HLB-resistant citrus.
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Affiliation(s)
- Hui Li
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
| | - Xiaobao Ying
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Lina Shang
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
| | - Bryce Redfern
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Nicholas Kypraios
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Xuejun Xie
- Changzhou Institute of Technology, Changzhou 213032, China;
| | - FeiFei Xu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Shaopeng Wang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Jinghua Zhang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Hongju Jian
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
| | - Hongtao Yu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Dianqiu Lv
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
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12
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Tran TT, Clark K, Ma W, Mulchandani A. Detection of a secreted protein biomarker for citrus Huanglongbing using a single-walled carbon nanotubes-based chemiresistive biosensor. Biosens Bioelectron 2020; 147:111766. [DOI: 10.1016/j.bios.2019.111766] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/24/2019] [Accepted: 10/07/2019] [Indexed: 01/17/2023]
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13
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Ying X, Wan M, Hu L, Zhang J, Li H, Lv D. Identification of the Virulence Factors of Candidatus Liberibacter asiaticus via Heterologous Expression in Nicotiana benthamiana using Tobacco Mosaic Virus. Int J Mol Sci 2019; 20:E5575. [PMID: 31717281 PMCID: PMC6888081 DOI: 10.3390/ijms20225575] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 10/31/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022] Open
Abstract
Huanglongbing (HLB), also known as citrus greening, is the most destructive disease of citrus worldwide. HLB is associated with the non-culturable bacterium, Candidatus Liberibacter asiaticus (CaLas) in the United States. The virulence mechanism of CaLas is largely unknown, partly because of the lack of a mutant library. In this study, Tobacco mosaic virus (TMV) and Nicotiana benthamiana (N. benthamiana) were used for large-scale screening of the virulence factors of CaLas. Agroinfiltration of 60 putative virulence factors in N. benthamiana led to the identification of four candidates that caused severe symptoms in N. benthamiana, such as growth inhibition and cell death. CLIBASIA_05150 and CLIBASIA_04065C (C-terminal of CLIBASIA_04065) could cause cell death in the infiltrated leaves at five days post infiltration. Two low-molecular-weight candidates, CLIBASIA_00470 and CLIBASIA_04025, could inhibit plant growth. By converting start codon to stop codon or frameshifting, the four genes lost their harmful effects to N. benthamiana. It indicated that the four virulence factors functioned at the protein level rather than at the RNA level. The subcellular localization of the four candidates was determined by confocal laser scanning microscope. CLIBASIA_05150 located in the Golgi apparatus; CLIBASIA_04065 located in the mitochondrion; CLIBASIA_00470 and CLIBASIA_04025 distributed in cells as free GFP. The host proteins interacting with the four virulence factors were identified by yeast two-hybrid. The host proteins interacting with CLIBASIA_00470 and CLIBASIA_04025 were overlapping. Based on the phenotypes, the subcellular localization and the host proteins identified by yeast two-hybrid, CLIBASIA_00470 and CLIBASIA_04025, functioned redundantly. The hypothesis of CaLas virulence was proposed. CaLas affects citrus development and suppresses citrus disease resistance, comprehensively, in a complicated manner. Ubiquitin-mediated protein degradation might play a vital role in CaLas virulence. Deep characterization of the interactions between the identified virulence factors and their prey will shed light on HLB. Eventually, it will help in developing HLB-resistant citrus and save the endangered citrus industry worldwide.
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Affiliation(s)
- Xiaobao Ying
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA;
| | - Mengyuan Wan
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, Chongqing 400715, China
| | - Linshuang Hu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China; (L.H.); (J.Z.)
| | - Jinghua Zhang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China; (L.H.); (J.Z.)
| | - Hui Li
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
| | - Dianqiu Lv
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, Chongqing 400715, China
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14
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Cruz-Munoz M, Munoz-Beristain A, Petrone JR, Robinson MA, Triplett EW. Growth parameters of Liberibacter crescens suggest ammonium and phosphate as essential molecules in the Liberibacter-plant host interface. BMC Microbiol 2019; 19:222. [PMID: 31606047 PMCID: PMC6790036 DOI: 10.1186/s12866-019-1599-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 09/20/2019] [Indexed: 12/25/2022] Open
Abstract
Background Liberibacter crescens is the closest cultured relative of four important uncultured crop pathogens. Candidatus. L. asiaticus, L. americanus, L. africanus cause citrus greening disease, while Ca. L. solanacearum causes potato Zebra chip disease. None of the pathogens grows in axenic culture. L. crescens grows in three media: a BM-7, a serum-free Hi® Grace’s Insect Medium (Hi-GI), and a chemically-defined medium called M15. To date, no optimal growth parameters of the model species L. crescens have been reported. Studying the main growth parameters of L. crescens in axenic culture will give us insights into the lifestyle of the Ca. Liberibacter pathogens. Results The evaluation of the growth parameters—pH, aeration, temperature, and buffering capacity—reflects the optimal living conditions of L. crescens. These variables revealed that L. crescens is an aerobic, neutrophilic bacterium, that grows optimally in broth in a pH range of 5.8 to 6.8, in a fully oxygenated environment (250 rpm), at 28 °C, and with monosodium phosphate (10 mM or 11.69 mM) as the preferred buffer for growth. The increase of pH in the external media likely results from the deamination activity within the cell, with the concomitant over-production of ammonium in the external medium. Conclusion L. crescens and the Ca. Liberibacter pathogens are metabolically similar and grow in similar environments—the phloem and the gut of their insect vectors. The evaluation of the growth parameters of L. crescens reveals the lifestyle of Liberibacter, elucidating ammonium and phosphate as essential molecules for colonization within the hosts. Ammonium is the main driver of pH modulation by active deamination of amino acids in the L. crescens amino acid rich media. In plants, excess ammonium induces ionic imbalances, oxidative stress, and pH disturbances across cell membranes, causing stunted root and shoot growth and chlorosis—the common symptoms of HLB-disease. Phosphate, which is also present in Ca. L. asiaticus hosts, is the preferred buffer for the growth of L. crescens. The interplay between ammonium, sucrose, potassium (K+), phosphate, nitrate (NO3−), light and other photosynthates might lead to develop better strategies for disease management.
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Affiliation(s)
- Maritsa Cruz-Munoz
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Alam Munoz-Beristain
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Joseph R Petrone
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Matthew A Robinson
- Biostatistics Department, College of Health Professions and College of Medicine, University of Florida, Gainesville, FL, USA
| | - Eric W Triplett
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA.
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15
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Lessons from One Fastidious Bacterium to Another: What Can We Learn about Liberibacter Species from Xylella fastidiosa. INSECTS 2019; 10:insects10090300. [PMID: 31527458 PMCID: PMC6780969 DOI: 10.3390/insects10090300] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 02/06/2023]
Abstract
Huanglongbing is causing economic devastation to the citrus industry in Florida, and threatens the industry everywhere the bacterial pathogens in the Candidatus Liberibacter genus and their insect vectors are found. Bacteria in the genus cannot be cultured and no durable strategy is available for growers to control plant infection or pathogen transmission. However, scientists and grape growers were once in a comparable situation after the emergence of Pierce’s disease, which is caused by Xylella fastidiosa and spread by its hemipteran insect vector. Proactive quarantine and vector control measures coupled with interdisciplinary data-driven science established control of this devastating disease and pushed the frontiers of knowledge in the plant pathology and vector biology fields. Our review highlights the successful strategies used to understand and control X. fastidiosa and their potential applicability to the liberibacters associated with citrus greening, with a focus on the interactions between bacterial pathogen and insect vector. By placing the study of Candidatus Liberibacter spp. within the current and historical context of another fastidious emergent plant pathogen, future basic and applied research to develop control strategies can be prioritized.
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16
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A high-throughput system to identify inhibitors of Candidatus Liberibacter asiaticus transcription regulators. Proc Natl Acad Sci U S A 2019; 116:18009-18014. [PMID: 31427509 DOI: 10.1073/pnas.1905149116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Citrus greening disease, also known as huanglongbing (HLB), is the most devastating disease of Citrus worldwide. This incurable disease is caused primarily by the bacterium Candidatus Liberibacter asiaticus and spread by feeding of the Asian Citrus Psyllid, Diaphorina citri Ca L. asiaticus cannot be cultured; its growth is restricted to citrus phloem and the psyllid insect. Management of infected trees includes use of broad-spectrum antibiotics, which have disadvantages. Recent work has sought to identify small molecules that inhibit Ca L. asiaticus transcription regulators, based on a premise that at least some regulators control expression of genes necessary for virulence. We describe a synthetic, high-throughput screening system to identify compounds that inhibit activity of Ca L. asiaticus transcription activators LdtR, RpoH, and VisNR. Our system uses the closely related model bacterium, Sinorhizobium meliloti, as a heterologous host for expression of a Ca L. asiaticus transcription activator, the activity of which is detected through expression of an enhanced green fluorescent protein (EGFP) gene fused to a target promoter. We used this system to screen more than 120,000 compounds for compounds that inhibited regulator activity, but not growth. Our screen identified several dozen compounds that inhibit regulator activity in our assay. This work shows that, in addition to providing a means of characterizing Ca L. asiaticus regulators, an S. meliloti host can be used for preliminary identification of candidate inhibitory molecules.
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17
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da Silva PA, Fassini CG, Sampaio LS, Dequigiovanni G, Zucchi MI, Wulff NA. Genetic Diversity of ' Candidatus Liberibacter asiaticus' Revealed by Short Tandem Repeats and Prophage Typing Indicates Population Homogeneity in Brazil. PHYTOPATHOLOGY 2019; 109:960-971. [PMID: 30694114 DOI: 10.1094/phyto-08-18-0295-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
'Candidatus Liberibacter asiaticus' is the most common huanglongbing-associated bacteria, being present in Asia, South, Central, and North America. Genomic approaches enabled sequencing of 'Ca. L. asiaticus' genomes, allowing for a broader assessment of its genetic variability with the application of polymerase chain reaction (PCR)-based tools such as microsatellite or short tandem repeat (STR) analysis. Although these tools contributed to a detailed analysis of strains from Japan, China, and the United States, Brazilian strains were analyzed in either too few samples with several STRs or in several strains with only a single microsatellite and a single PCR marker. We used 573 'Ca. L. asiaticus' strains, mainly collected from São Paulo State (SPS), in our genetic analyses, employing three STRs and several prophage PCR markers. STR revealed a homogeneous population regardless of sampling year or geographic regions of SPS. Thirty-eight haplotypes were recognized with a predominance of VNTR_005 higher than 10 repeats, with VNTR_002 and VNTR_077 containing 11 and 8 repeats, respectively. This haplotype is indicated as class HE, which comprised 80.28% of strains. Classes HA and HB, predominant in Florida, were not found. A new genomic organization in the junction of prophages SC2 and SC1 is prevalent in Brazilian strains, indicating gene rearrangement and a widespread occurrence of a type 1 prophage as well as the presence of a type 2-like prophage. Our results indicate that 'Ca. L. asiaticus' populations are homogeneous and harbor a new genomic organization in prophages type 1 and 2.
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Affiliation(s)
| | - Camila Giacomo Fassini
- 1 Departamento de Pesquisa & Desenvolvimento-Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | - Laís Simões Sampaio
- 1 Departamento de Pesquisa & Desenvolvimento-Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | - Gabriel Dequigiovanni
- 2 Agência Paulista de Tecnologia dos Agronegócios, Polo Regional Centro-Sul, Rodovia SP 127, km 30, Piracicaba, SP, 13400-970 Brazil; and
| | - Maria Imaculada Zucchi
- 2 Agência Paulista de Tecnologia dos Agronegócios, Polo Regional Centro-Sul, Rodovia SP 127, km 30, Piracicaba, SP, 13400-970 Brazil; and
| | - Nelson Arno Wulff
- 1 Departamento de Pesquisa & Desenvolvimento-Fundecitrus, Araraquara, SP, 14807-040, Brazil
- 3 PPG Biotecnologia, IQ/UNESP Araraquara, SP, 14800-060, Brazil
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18
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Wulff NA, Fassini CG, Marques VV, Martins EC, Coletti DAB, Teixeira DDC, Sanches MM, Bové JM. Molecular Characterization and Detection of 16SrIII Group Phytoplasma Associated with Huanglongbing Symptoms. PHYTOPATHOLOGY 2019; 109:366-374. [PMID: 30226423 DOI: 10.1094/phyto-03-18-0081-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
When huanglongbing (HLB) was found in Brazil in 2004, 'Candidatus Liberibacter americanus' was infecting most of the trees while 'Ca. L. asiaticus' was present in a minor proportion. Currently, 'Ca. L. asiaticus' is the predominant bacterium associated with HLB in citrus trees in São Paulo (SP) and Minas Gerais (MG) States, the major citrus-growing regions in Brazil. A phytoplasma from the 16SrIX group was associated with HLB symptoms in Brazil in 2007, in plants free of Liberibacter spp. In this report, HLB samples testing negative for 'Ca. L. asiaticus', 'Ca. L. americanus', and 16SrIX phytoplasma were infected with 16SrIII phytoplasmas. Coinfection with 'Ca. L. asiaticus' and 16SrIII was also found. The 16S ribosomal RNA (rRNA) gene sequences from 22 samples were obtained and sequenced, confirming that the 16SrIII group phytoplasma is associated with HLB symptoms in SP and MG States. Ten single-nucleotide polymorphisms (SNPs) were found in the 1,427-bp 16S rRNA gene sequences from 16SrIII phytoplasmas from citrus, whereas none was detected in 16S rRNA gene sequences among 16SrIX phytoplasma from citrus. Ribosomal protein (rp) rpsSrplVrpsC gene sequences were amplified with 16SrIII group-specific primers, sequenced from a subset of nine samples, and assembled into three groups based on eight SNPs. SNPs in 16S rRNA gene and rp gene sequences are common in 16SrIII phytoplasmas from other hosts and this phytoplasma group is widespread in South America. 16SrIII phytoplasmas highly related are commonly found in Melia azedarach, a widespread tree in Brazil and Argentina. The finding of a new phytoplasma associated with HLB symptoms belonging to the 16SrIII group reinforces the need to develop diagnostic tools to assess HLB-associated microbiomes.
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Affiliation(s)
- Nelson Arno Wulff
- 1 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040 and PPG Biotecnologia, IQ/UNESP Araraquara, SP, 14800-060. Brazil
| | - Camila Giacomo Fassini
- 2 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | - Viviani Vieira Marques
- 2 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | - Elaine Cristina Martins
- 2 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | | | - Diva do Carmo Teixeira
- 2 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040, Brazil
| | | | - Joseph Marie Bové
- 2 Departamento de Pesquisa & Desenvolvimento, Fundecitrus, Araraquara, SP, 14807-040, Brazil
- 4 UMR 1332 Biologie du Fruit et Pathologie, Université de Bordeaux, INRA, 71 avenue Edouard Bourlaux, CS20032, F-33882 Villenave d'Ornon Cedex, France
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19
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Wu F, Huang J, Xu M, Fox EGP, Beattie GAC, Holford P, Cen Y, Deng X. Host and environmental factors influencing 'Candidatus Liberibacter asiaticus' acquisition in Diaphorina citri. PEST MANAGEMENT SCIENCE 2018; 74:2738-2746. [PMID: 29726075 DOI: 10.1002/ps.5060] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/14/2018] [Accepted: 05/03/2018] [Indexed: 05/27/2023]
Abstract
BACKGROUND Diaphorina citri is a vector of 'Candidatus Liberibacter asiaticus' (CLas) associated with citrus Huanglongbing. In this study, the infection and titers of CLas in the psyllid, were monitored for life cycle stage, sex, host-plant CLas titer, host-plant genotype, and ambient temperature. RESULTS Acquisition efficiency of CLas by D. citri was highest in nymphs reared at 25 °C on a host plant with high CLas titers but was independent of the host genotypes assessed and of vector sex. We further observed that D. citri nymphs acquired CLas more rapidly than adults based on acquisition access periods (AAPs). CLas did not multiply in the alimentary canal, hemolymph, and salivary glands of adults for 18 days after a 3-day AAP as adult. However, CLas multiplication was detected in hemolymph and salivary gland of adults after the bacterium was acquired by nymphs. Eighty percent of salivary glands of adults contained CLas 18 days after a 3-day AAP as nymph compared to 10% 18 days after a 3-day AAP as adults. CONCLUSION Different factors tested herein influenced CLas acquisition efficiency of D. citri, CLas multiplication and spread inside the psyllid. These observations serve to better understand mechanisms of CLas infection in D. citri. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Fengnian Wu
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
| | - Jiaquan Huang
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
| | - Meirong Xu
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
| | - Eduardo G P Fox
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
| | - G Andrew C Beattie
- School of Science and Health, Western Sydney University, Penrith, New South Wales, Australia
| | - Paul Holford
- School of Science and Health, Western Sydney University, Penrith, New South Wales, Australia
| | - Yijing Cen
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
| | - Xiaoling Deng
- Citrus Huanglongbing Research Laboratory/Laboratory of Insect Ecology, South China Agricultural University, Guangzhou, China
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Hilf ME, Luo W. Dynamics of 'Candidatus Liberibacter asiaticus' Colonization of New Growth of Citrus. PHYTOPATHOLOGY 2018; 108:1165-1171. [PMID: 29757704 DOI: 10.1094/phyto-12-17-0408-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
'Candidatus Liberibacter asiaticus' is a phloem-colonizing intracellular bacterial pathogen of citrus associated with the disease huanglongbing. A study of patterns of colonization and bacterial population growth in new growth of different citrus types was conducted by pruning infected citron, sweet orange, sour orange, mandarin, citrange, and Citrus macrophylla trees to force the growth of axillary and adventitious shoots. The first three leaves on newly emerged shoots were collected at 30, 60, and 90 days to assess colonization and population growth of 'Ca. L. asiaticus' using real time PCR (qPCR). Single trials were conducted with mandarin and citron, two trials each for citrange, sour orange and sweet orange, and four trials for C. macrophylla. In citron the proportion of colonized leaves increased significantly over time, with 67, 85, and 96% of leaves colonized at 30, 60, and 90 days, respectively. For the other citrus types, the exact proportion of colonized leaves differed, but colonization exceeded 60% in mandarin, sour orange, and citrange, and exceeded 80% at 30 days in two trials with sweet orange and three trials with C. macrophylla, but there was no significant increase in the proportion of colonized leaves at 60 and 90 days. Bacteria were readily detected by 30 days in new leaves of all citrus types. Differences in the growth of the bacterial population between citrus types and at different times of the year were noted, but common trends were apparent. In general, bacterial titers peaked at 60 days, except in leaves of C. macrophylla where bacterial titers peaked at 30 days. The early and consistently high proportion of leaf colonization observed for new growth of sweet orange during two trials and for C. macrophylla during three trials indicates a near synchronous colonization of new leaves by 30 days.
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Affiliation(s)
- Mark E Hilf
- First author: U.S. Department of Agriculture-Agriculture Research Service (USDA-ARS), 2001 South Rock Road, Fort Pierce, FL 34945; and second author: USDA-ARS, Fort Pierce, Florida and North Carolina State University, Center for Integrated Pest Management, Raleigh 27606
| | - Weiqi Luo
- First author: U.S. Department of Agriculture-Agriculture Research Service (USDA-ARS), 2001 South Rock Road, Fort Pierce, FL 34945; and second author: USDA-ARS, Fort Pierce, Florida and North Carolina State University, Center for Integrated Pest Management, Raleigh 27606
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21
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Kaur P, Gonzalez P, Dutt M, Etxeberria E. Identification of sieve elements and companion cell protoplasts by a combination of brightfield and fluorescence microscopy. APPLICATIONS IN PLANT SCIENCES 2018; 6:e01179. [PMID: 30276027 PMCID: PMC6159646 DOI: 10.1002/aps3.1179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Phloem-limited diseases are becoming increasingly pervasive, threatening the existence of crops worldwide. Studies of phloem diseases are complicated by the inaccessibility of the phloem tissue. Phloem cells are located deep inside the plant body, are interspersed with other cell types, are among the smallest cells in the plant kingdom, and make up a small percentage of the total cell population in a plant. These properties make phloem cells difficult to investigate. METHODS We used leaf midrib protoplasts and a combination of organelle-specific dyes including Neutral Red (acidic compartments), MitoTracker Green (mitochondria), Hoechst 3342 (nucleus), and chloroplast autofluorescence. We examined the protoplasts under light and fluorescence microscopy. RESULTS When observed using brightfield and fluorescence microscopy, sieve element protoplasts were distinguished by the lack of vacuole and a nucleus, and by containing various mitochondria. Companion cells showed a dense cytoplasm and various small vacuoles. They also revealed their characteristic large nucleus and abundant mitochondria. DISCUSSION We present evidence that a combination of organelle-specific dyes and autofluorescence allows for the identification of sieve elements and companion cell protoplasts from citrus leaf tissue.
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Affiliation(s)
- Prabhjot Kaur
- Citrus Research and Education CenterDepartment of Horticultural SciencesInstitute of Food and Agricultural SciencesUniversity of FloridaLake AlfredFlorida33850USA
| | - Pedro Gonzalez
- Citrus Research and Education CenterDepartment of Horticultural SciencesInstitute of Food and Agricultural SciencesUniversity of FloridaLake AlfredFlorida33850USA
| | - Manjul Dutt
- Citrus Research and Education CenterDepartment of Horticultural SciencesInstitute of Food and Agricultural SciencesUniversity of FloridaLake AlfredFlorida33850USA
| | - Ed Etxeberria
- Citrus Research and Education CenterDepartment of Horticultural SciencesInstitute of Food and Agricultural SciencesUniversity of FloridaLake AlfredFlorida33850USA
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Munir S, He P, Wu Y, He P, Khan S, Huang M, Cui W, He P, He Y. Huanglongbing Control: Perhaps the End of the Beginning. MICROBIAL ECOLOGY 2018; 76:192-204. [PMID: 29196843 DOI: 10.1007/s00248-017-1123-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/23/2017] [Indexed: 05/25/2023]
Abstract
Huanglongbing (HLB) is one of the most destructive citrus plant diseases worldwide. It is associated with the fastidious phloem-limited α-proteobacteria 'Candidatus Liberibacter asiaticus', 'Ca. Liberibacter africanus' and 'Ca. Liberibacter americanus'. In recent years, HLB-associated Liberibacters have extended to North and South America. The causal agents of HLB have been putatively identified, and their transmission pathways and worldwide population structure have been extensively studied. However, very little is known about the epidemiologic relationships of Ca. L. asiaticus, which has limited the scope of HLB research and especially the development of control strategies. HLB-affected plants produce damaged fruits and die within several years. To control the disease, scientists have developed new compounds and screened existing compounds for their antibiotic and antimicrobial activities against the disease. These compounds, however, have very little or even no effect on the disease. The aim of the present review was to compile and compare different methods of HLB disease control with newly developed integrative strategies. In light of recent studies, we also describe how to control the vectors of this disease and the biological control of other citrus plant pathogens. This work could steer the attention of scientists towards integrative control strategies.
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Affiliation(s)
- Shahzad Munir
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengfei He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Yixin Wu
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengbo He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Sehroon Khan
- World Agroforestry Centre, East and Central Asia, 132 Lanhei Rd, Heilongtan, Kunming, Yunnan, 650201, China
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
| | - Min Huang
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
- Agriculture College and Urban Modern Agriculture Engineering Research Center, Kunming University, Kunming, 650214, China
| | - Wenyan Cui
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengjie He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Yueqiu He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China.
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23
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Killiny N, Jones SE. Metabolic alterations in the nymphal instars of Diaphorina citri induced by Candidatus Liberibacter asiaticus, the putative pathogen of huanglongbing. PLoS One 2018; 13:e0191871. [PMID: 29370262 PMCID: PMC5785020 DOI: 10.1371/journal.pone.0191871] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/12/2018] [Indexed: 11/24/2022] Open
Abstract
Currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. The disease is caused by the Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). The pathogen is transmitted in a persistent propagative circulative manner within its vector, the Asian citrus psyllid, Diaphorina citri. Exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of CLas and to designing an artificial medium for culturing the pathogen. It has been shown that the nymphal stages have a greater role in transmission mainly because they feed on plants more actively than adults. In this study, we carried out an untargeted comparative metabolomic analysis for healthy and CLas-infected 4th / 5th instar nymphs. The metabolic analysis was performed using trimethylsilylation and methyl chloroformate derivatization followed by Gas Chromatography-Mass Spectrometry (GC-MS). Overall, the changes in the nymph metabolism due to the infection with CLas were more pronounced than in adults, as we previously published. Nymphs reared on CLas-infected Valencia sweet orange were higher in many metabolites, mainly those of the TCA cycle, C16 and C18 fatty acids, glucose, sucrose, L-proline, L-serine, pyroglutamic acid, saccharic acid, threonic acid and myo-inositol than those reared on healthy plants. In contrast, CLas-infected nymphs were lower in putrescine, glycine, L -phenylalanine, L -tyrosine, L -valine, and chiro-inositol. The information provided from this study may contribute in acceleration of the availability of CLas in culture and consequent screening of antibacterial compounds to discover a definitive solution for huanglongbing.
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Affiliation(s)
- Nabil Killiny
- Citrus Research and Education Center, Department of Plant Pathology, IFAS, University of Florida, Lake Alfred, Florida, United States of America
| | - Shelley E Jones
- Citrus Research and Education Center, Department of Plant Pathology, IFAS, University of Florida, Lake Alfred, Florida, United States of America
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Balan B, Ibáñez AM, Dandekar AM, Caruso T, Martinelli F. Identifying Host Molecular Features Strongly Linked With Responses to Huanglongbing Disease in Citrus Leaves. FRONTIERS IN PLANT SCIENCE 2018; 9:277. [PMID: 29541089 PMCID: PMC5836289 DOI: 10.3389/fpls.2018.00277] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A bioinformatic analysis of previously published RNA-Seq studies on Huanglongbing (HLB) response and tolerance in leaf tissues was performed. The aim was to identify genes commonly modulated between studies and genes, pathways and gene set categories strongly associated with this devastating Citrus disease. Bioinformatic analysis of expression data of four datasets present in NCBI provided 46-68 million reads with an alignment percentage of 72.95-86.76%. Only 16 HLB-regulated genes were commonly identified between the three leaf datasets. Among them were key genes encoding proteins involved in cell wall modification such as CESA8, pectinesterase, expansin8, expansin beta 3.1, and a pectate lyase. Fourteen HLB-regulated genes were in common between all four datasets. Gene set enrichment analysis showed some different gene categories affected by HLB disease. Although sucrose and starch metabolism was highly linked with disease symptoms, different genes were significantly regulated depending on leaf growth and infection stages and experimental conditions. Histone-related transcription factors were highly affected by HLB in the analyzed RNA-Seq datasets. HLB tolerance was linked with induction of proteins involved in detoxification. Protein-protein interaction (PPI) network analysis confirmed a possible role for heat shock proteins in curbing disease progression.
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Affiliation(s)
- Bipin Balan
- Dipartimento di Scienze Agrarie, Alimentari e Forestali, Università degli Studi di Palermo, Palermo, Italy
| | - Ana M. Ibáñez
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Abhaya M. Dandekar
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Tiziano Caruso
- Dipartimento di Scienze Agrarie, Alimentari e Forestali, Università degli Studi di Palermo, Palermo, Italy
| | - Federico Martinelli
- Dipartimento di Scienze Agrarie, Alimentari e Forestali, Università degli Studi di Palermo, Palermo, Italy
- *Correspondence: Federico Martinelli,
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25
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Pan L, Gardner CL, Pagliai FA, Gonzalez CF, Lorca GL. Identification of the Tolfenamic Acid Binding Pocket in PrbP from Liberibacter asiaticus. Front Microbiol 2017; 8:1591. [PMID: 28878750 PMCID: PMC5572369 DOI: 10.3389/fmicb.2017.01591] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 08/04/2017] [Indexed: 12/31/2022] Open
Abstract
In Liberibacter asiaticus, PrbP is an important transcriptional accessory protein that was found to regulate gene expression through interactions with the RNA polymerase β-subunit and a specific sequence on the promoter region. It was found that inactivation of PrbP, using the inhibitor tolfenamic acid, resulted in a significant decrease in the overall transcriptional activity of L. asiaticus, and the suppression of L. asiaticus infection in HLB symptomatic citrus seedlings. The molecular interactions between PrbP and tolfenamic acid, however, were yet to be elucidated. In this study, we modeled the structure of PrbP and identified a ligand binding pocket, TaP, located at the interface of the predicted RNA polymerase interaction domain (N-terminus) and the DNA binding domain (C-terminus). The molecular interactions of PrbP with tolfenamic acid were predicted using in silico docking. Site-directed mutagenesis of specific amino acids was followed by electrophoresis mobility shift assays and in vitro transcription assays, where residues N107, G109, and E148 were identified as the primary amino acids involved in interactions with tolfenamic acid. These results provide insight into the binding mechanism of PrbP to a small inhibitory molecule, and a starting scaffold for the identification and development of therapeutics targeting PrbP and other homologs in the CarD_CdnL_TRCF family.
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Affiliation(s)
| | | | | | | | - Graciela L. Lorca
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of FloridaGainesville, FL, United States
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Wang N, Pierson EA, Setubal JC, Xu J, Levy JG, Zhang Y, Li J, Rangel LT, Martins J. The Candidatus Liberibacter-Host Interface: Insights into Pathogenesis Mechanisms and Disease Control. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017. [PMID: 28637377 DOI: 10.1146/annurev-phyto-080516-035513] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
"Candidatus Liberibacter" species are associated with economically devastating diseases of citrus, potato, and many other crops. The importance of these diseases as well as the proliferation of new diseases on a wider host range is likely to increase as the insects vectoring the "Ca. Liberibacter" species expand their territories worldwide. Here, we review the progress on understanding pathogenesis mechanisms of "Ca. Liberibacter" species and the control approaches for diseases they cause. We discuss the Liberibacter virulence traits, including secretion systems, putative effectors, and lipopolysaccharides (LPSs), as well as other important traits likely to contribute to disease development, e.g., flagella, prophages, and salicylic acid hydroxylase. The pathogenesis mechanisms of Liberibacters are discussed. Liberibacters secrete Sec-dependent effectors (SDEs) or other virulence factors into the phloem elements or companion cells to interfere with host targets (e.g., proteins or genes), which cause cell death, necrosis, or other phenotypes of phloem elements or companion cells, leading to localized cell responses and systemic malfunction of phloem. Receptors on the remaining organelles in the phloem, such as plastid, vacuole, mitochondrion, or endoplasmic reticulum, interact with secreted SDEs and/or other virulence factors secreted or located on the Liberibacter outer membrane to trigger cell responses. Some of the host genes or proteins targeted by SDEs or other virulence factors of Liberibacters serve as susceptibility genes that facilitate compatibility (e.g., promoting pathogen growth or suppressing immune responses) or disease development. In addition, Liberibacters trigger plant immunity response via pathogen-associated molecular patterns (PAMPs, such as lipopolysaccharides), which leads to premature cell death, callose deposition, or phloem protein accumulation, causing a localized response and/or systemic effect on phloem transportation. Physical presence of Liberibacters and their metabolic activities may disturb the function of phloem, via disrupting osmotic gradients, or the integrity of phloem conductivity. We also review disease management strategies, including promising new technologies. Citrus production in the presence of Huanglongbing is possible if the most promising management approaches are integrated. HLB management is discussed in the context of local, area-wide, and regional Huanglongbing/Asian Citrus Psyllid epidemiological zones. For zebra chip disease control, aggressive psyllid management enables potato production, although insecticide resistance is becoming an issue. Meanwhile, new technologies such as clustered regularly interspaced short palindromic repeat (CRISPR)-derived genome editing provide an unprecedented opportunity to provide long-term solutions.
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Affiliation(s)
- Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Elizabeth A Pierson
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - João Carlos Setubal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Julien G Levy
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - Yunzeng Zhang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Luiz Thiberio Rangel
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Joaquim Martins
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
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Pitino M, Armstrong CM, Duan Y. Molecular mechanisms behind the accumulation of ATP and H 2O 2 in citrus plants in response to ' Candidatus Liberibacter asiaticus' infection. HORTICULTURE RESEARCH 2017; 4:17040. [PMID: 35211319 PMCID: PMC7713647 DOI: 10.1038/hortres.2017.40] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/29/2017] [Accepted: 07/05/2017] [Indexed: 05/22/2023]
Abstract
Candidatus Liberibacter asiaticus (Las) is a fastidious, phloem-restricted pathogen with a significantly reduced genome, and attacks all citrus species with no immune cultivars documented to date. Like other plant bacterial pathogens, Las deploys effector proteins into the organelles of plant cells, such as mitochondria and chloroplasts to manipulate host immunity and physiology. These organelles are responsible for the synthesis of adenosine triphosphate (ATP) and have a critical role in plant immune signaling during hydrogen peroxide (H2O2) production. In this study, we investigated H2O2 and ATP accumulation in relation to citrus huanglongbing (HLB) in addition to revealing the expression profiles of genes critical for the production and detoxification of H2O2 and ATP synthesis. We also found that as ATP and H2O2 concentrations increased in the leaf, so did the severity of the HLB symptoms, a trend that remained consistent among the four different citrus varieties tested. Furthermore, the upregulation of ATP synthase, a key enzyme for energy conversion, may contribute to the accumulation of ATP in infected tissues, whereas downregulation of the H2O2 detoxification system may cause oxidative damage to plant macromolecules and cell structures. This may explain the cause of some of the HLB symptoms such as chlorosis or leaf discoloration. The findings in this study highlight important molecular and physiological mechanisms involved in the host plants' response to Las infection and provide new targets for interrupting the disease cycle.
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Affiliation(s)
- Marco Pitino
- USDA-ARS, US Horticultural Research Laboratory, 2001 S. Rock Road, Fort Pierce, 34945 FL USA
| | - Cheryl M Armstrong
- USDA-ARS, US Horticultural Research Laboratory, 2001 S. Rock Road, Fort Pierce, 34945 FL USA
| | - Yongping Duan
- USDA-ARS, US Horticultural Research Laboratory, 2001 S. Rock Road, Fort Pierce, 34945 FL USA
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Martinelli F, Reagan RL, Dolan D, Fileccia V, Dandekar AM. Proteomic analysis highlights the role of detoxification pathways in increased tolerance to Huanglongbing disease. BMC PLANT BIOLOGY 2016; 16:167. [PMID: 27465111 PMCID: PMC4963945 DOI: 10.1186/s12870-016-0858-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/20/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Huanglongbing (HLB) disease is still the greatest threat to citriculture worldwide. Although there is not any resistance source in the Citrus germplasm, a certain level of moderated tolerance is present. A large-scale analysis of proteomic responses of Citrus may help: 1) clarifying physiological and molecular effects of disease progression, 2) validating previous data at transcriptomic level, and 3) identifying biomarkers for development of early diagnostics, short-term therapeutics and long-term genetic resistance. RESULTS In this work we have conducted a proteomic analysis of mature leaves of two Citrus genotypes with well-known differing tolerances to HLB: Navel orange (highly susceptible) and Volkameriana (moderately tolerant). Pathway enrichment analysis showed that amino acid degradation processes occurred to a larger degree in the Navel orange. No clear differences between the two genotypes were observed for primary metabolic pathways. The most important finding was that four glutathione-S-transferases were upregulated in Volkameriana and not in Navel orange. These proteins are involved in radical ion detoxification. CONCLUSIONS Upregulation of proteins involved in radical ion detoxification should be considered as an important mechanism of increased tolerance to HLB.
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Affiliation(s)
- Federico Martinelli
- Department of Agricultural and Forest Sciences, University of Palermo, viale delle scienze ed. 4, 90128 Palermo, Italy
| | - Russell L. Reagan
- Plant Sciences Department, University of California, One Shields Avenue, 95616 Davis, CA USA
| | - David Dolan
- Plant Sciences Department, University of California, One Shields Avenue, 95616 Davis, CA USA
| | - Veronica Fileccia
- Department of Agricultural and Forest Sciences, University of Palermo, viale delle scienze ed. 4, 90128 Palermo, Italy
| | - Abhaya M. Dandekar
- Plant Sciences Department, University of California, One Shields Avenue, 95616 Davis, CA USA
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Molecular Responses to Small Regulating Molecules against Huanglongbing Disease. PLoS One 2016; 11:e0159610. [PMID: 27459099 PMCID: PMC4961454 DOI: 10.1371/journal.pone.0159610] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/06/2016] [Indexed: 11/19/2022] Open
Abstract
Huanglongbing (HLB; citrus greening) is the most devastating disease of citrus worldwide. No cure is yet available for this disease and infected trees generally decline after several months. Disease management depends on early detection of symptoms and chemical control of insect vectors. In this work, different combinations of organic compounds were tested for the ability to modulate citrus molecular responses to HLB disease beneficially. Three small-molecule regulating compounds were tested: 1) L-arginine, 2) 6-benzyl-adenine combined with gibberellins, and 3) sucrose combined with atrazine. Each treatment contained K-phite mineral solution and was tested at two different concentrations. Two trials were conducted: one in the greenhouse and the other in the orchard. In the greenhouse study, responses of 42 key genes involved in sugar and starch metabolism, hormone-related pathways, biotic stress responses, and secondary metabolism in treated and untreated mature leaves were analyzed. TGA5 was significantly induced by arginine. Benzyladenine and gibberellins enhanced two important genes involved in biotic stress responses: WRKY54 and WRKY59. Sucrose combined with atrazine mainly upregulated key genes involved in carbohydrate metabolism such as sucrose-phosphate synthase, sucrose synthase, starch synthase, and α-amylase. Atrazine also affected expression of some key genes involved in systemic acquired resistance such as EDS1, TGA6, WRKY33, and MYC2. Several treatments upregulated HSP82, which might help protect protein folding and integrity. A subset of key genes was chosen as biomarkers for molecular responses to treatments under field conditions. GPT2 was downregulated by all small-molecule treatments. Arginine-induced genes involved in systemic acquired resistance included PR1, WRKY70, and EDS1. These molecular data encourage long-term application of treatments that combine these regulating molecules in field trials.
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Ammar ED, Ramos JE, Hall DG, Dawson WO, Shatters RG. Acquisition, Replication and Inoculation of Candidatus Liberibacter asiaticus following Various Acquisition Periods on Huanglongbing-Infected Citrus by Nymphs and Adults of the Asian Citrus Psyllid. PLoS One 2016; 11:e0159594. [PMID: 27441694 PMCID: PMC4956146 DOI: 10.1371/journal.pone.0159594] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 06/29/2016] [Indexed: 11/18/2022] Open
Abstract
The Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), is the primary vector of Candidatus Liberibacter asiaticus (Las) implicated as causative agent of citrus huanglongbing (citrus greening), currently the most serious citrus disease worldwide. Las is transmitted by D. citri in a persistent-circulative manner, but the question of replication of this bacterium in its psyllid vector has not been resolved. Thus, we studied the effects of the acquisition access period (AAP) by nymphs and adults of D. citri on Las acquisition, multiplication and inoculation/transmission. D. citri nymphs or adults (previously non-exposed to Las) were caged on Las-infected citrus plants for an AAP of 1, 7 or 14 days. These 'Las-exposed' psyllids were then transferred weekly to healthy citrus or orange jasmine plants, and sampled via quantitative polymerase chain reaction (qPCR) analysis 1-42 days post-first access to diseased plants (padp); all tested nymphs became adults 7-14 days padp. Our results indicate that following 1 or 7 day AAP as nymphs 49-59% of Las-exposed psyllids became Las-infected (qPCR-positive), whereas only 8-29% of the psyllids were infected following 1-14 day AAP as adults. Q-PCR analysis also indicated that Las titer in the Las-exposed psyllids (relative to that of the psyllid S20 ribosomal protein gene) was: 1) significantly higher, and increasing at a faster rate, following Las acquisition as nymphs compared to that following Las acquisition as adults; 2) higher as post-acquisition time of psyllids on healthy plants increased reaching a peak at 14-28 days padp for nymphs and 21-35 days padp for adults, with Las titer decreasing or fluctuating after that; 3) higher with longer AAP on infected plants, especially with acquisition as adults. Our results strongly suggest that Las multiplies in both nymphs and adults of D. citri but attains much higher levels in a shorter period of time post-acquisition when acquired by nymphs than when acquired by adults, and that adults may require longer access to infected plants compared to nymphs for Las to reach higher levels in the vector. However, under the conditions of our experiments, only D. citri that had access to infected plants as nymphs were able to inoculate Las into healthy citrus seedlings or excised leaves. The higher probability of Las inoculation into citrus by psyllids when they have acquired this bacterium from infected plants during the nymphal rather than the adult stage, as reported by us and others, has significant implications in the epidemiology and control of this economically important citrus disease.
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Affiliation(s)
- El-Desouky Ammar
- United States Department of Agriculture-Agricultural Research Service, Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
- University of Florida, IFAS-CREC, Lake Alfred, Florida, United States of America
| | - John E. Ramos
- United States Department of Agriculture-Agricultural Research Service, Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - David G. Hall
- United States Department of Agriculture-Agricultural Research Service, Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - William O. Dawson
- University of Florida, IFAS-CREC, Lake Alfred, Florida, United States of America
| | - Robert G. Shatters
- United States Department of Agriculture-Agricultural Research Service, Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
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Yang C, Powell CA, Duan Y, Shatters R, Fang J, Zhang M. Deciphering the Bacterial Microbiome in Huanglongbing-Affected Citrus Treated with Thermotherapy and Sulfonamide Antibiotics. PLoS One 2016; 11:e0155472. [PMID: 27171468 PMCID: PMC4865244 DOI: 10.1371/journal.pone.0155472] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/26/2016] [Indexed: 11/23/2022] Open
Abstract
Huanglongbing (HLB) is a serious citrus disease that threatens the citrus industry. In previous studies, sulfonamide antibiotics and heat treatment suppressed ‘Candidatus Liberibacter asiaticus’ (Las), but did not completely eliminate the Las. Furthermore, there are few reports studying the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. In this study, combinations of heat (45°C or 40°C) and sulfonamide treatment (sulfathiazole sodium–STZ, or sulfadimethoxine sodium—SDX) were applied to HLB-affected citrus. The bacterial microbiome of HLB-affected citrus following thermotherapy and/or chemotherapy was characterized by PhyloChipTMG3-based metagenomics. Our results showed that the combination of thermotherapy at 45°C and chemotherapy with STZ and SDX was more effective against HLB than thermotherapy alone, chemotherapy alone, or a combination of thermotherapy at 40°C and chemotherapy. The PhyloChipTMG3-based results indicated that 311 empirical Operational Taxonomic Units (eOTUs) were detected in 26 phyla. Cyanobacteria (18.01%) were dominant after thermo-chemotherapy. Thermotherapy at 45°C decreased eOTUs (64.43%) in leaf samples, compared with thermotherapy at 40°C (73.96%) or without thermotherapy (90.68%) and it also reduced bacterial family biodiversity. The eOTU in phylum Proteobacteria was reduced significantly and eOTU_28, representing “Candidatus Liberibacter,” was not detected following thermotherapy at 45°C. Following antibiotic treatment with SDX and STZ, there was enhanced abundance of specific eOTUs belonging to the families Streptomycetaceae, Desulfobacteraceae, Chitinophagaceae, and Xanthomonadaceae, which may be implicated in increased resistance to plant pathogens. Our study further develops an integrated strategy for combating HLB, and also provides new insight into the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics.
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Affiliation(s)
- Chuanyu Yang
- State Key Lab for Conservation and Utilization of Subtropical Agro-biological Resources, Guangxi University, Nanning, 530005, China
- Indian River Research and Education Center, IFAS, University of Florida, Fort Pierce, FL, 34945, United States of America
- College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Charles A. Powell
- Indian River Research and Education Center, IFAS, University of Florida, Fort Pierce, FL, 34945, United States of America
| | - Yongping Duan
- Horticultural Research Lab, USDA-ARS, Fort Pierce, FL, 34945, United States of America
| | - Robert Shatters
- Horticultural Research Lab, USDA-ARS, Fort Pierce, FL, 34945, United States of America
| | - Jingping Fang
- College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Muqing Zhang
- State Key Lab for Conservation and Utilization of Subtropical Agro-biological Resources, Guangxi University, Nanning, 530005, China
- Indian River Research and Education Center, IFAS, University of Florida, Fort Pierce, FL, 34945, United States of America
- College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- * E-mail:
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Lai KK, Davis-Richardson AG, Dias R, Triplett EW. Identification of the Genes Required for the Culture of Liberibacter crescens, the Closest Cultured Relative of the Liberibacter Plant Pathogens. Front Microbiol 2016; 7:547. [PMID: 27148230 PMCID: PMC4837290 DOI: 10.3389/fmicb.2016.00547] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 04/04/2016] [Indexed: 11/26/2022] Open
Abstract
Here Tn5 random transposon mutagenesis was used to identify the essential elements for culturing Liberibacter crescens BT-1 that can serve as antimicrobial targets for the closely related pathogens of citrus, Candidatus Liberibacter asiaticus (Las) and tomato and potato, Candidatus Liberibacter solanacearum (Lso). In order to gain insight on the virulence, metabolism, and culturability of the pathogens within the genus Liberibacter, a mini-Tn5 transposon derivative system consisting of a gene specifying resistance to kanamycin, flanked by a 19-base-pair terminal repeat sequence of Tn5, was used for the genome-wide mutagenesis of L. crescens BT-1 and created an insertion mutant library. By analyzing the location of insertions using Sanger and Illumina Mi-Seq sequencing, 314 genes are proposed as essential for the culture of L. crescens BT-1 on BM-7 medium. Of those genes, 76 are not present in the uncultured Liberibacter pathogens and, as a result, suggest molecules necessary for the culturing these pathogens. Those molecules include the aromatic amino acids, several vitamins, histidine, cysteine, lipopolysaccharides, and fatty acids. In addition, the 238 essential genes of L. crescens in common with L. asiaticus are potential targets for the development of therapeutics against the disease.
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Affiliation(s)
- Kin-Kwan Lai
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida Gainesville, FL, USA
| | - Austin G Davis-Richardson
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida Gainesville, FL, USA
| | - Raquel Dias
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida Gainesville, FL, USA
| | - Eric W Triplett
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida Gainesville, FL, USA
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da Graça JV, Douhan GW, Halbert SE, Keremane ML, Lee RF, Vidalakis G, Zhao H. Huanglongbing: An overview of a complex pathosystem ravaging the world's citrus. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:373-87. [PMID: 26466921 DOI: 10.1111/jipb.12437] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/12/2015] [Indexed: 05/24/2023]
Abstract
Citrus huanglongbing (HLB) has become a major disease and limiting factor of production in citrus areas that have become infected. The destruction to the affected citrus industries has resulted in a tremendous increase to support research that in return has resulted in significant information on both applied and basic knowledge concerning this important disease to the global citrus industry. Recent research indicates the relationship between citrus and the causal agent of HLB is shaped by multiple elements, in which host defense responses may also play an important role. This review is intended to provide an overview of the importance of HLB to a wider audience of plant biologists. Recent advances on host-pathogen interactions, population genetics and vectoring of the causal agent are discussed.
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Affiliation(s)
- John V da Graça
- Texas A&M University-Kingsville Citrus Center, Weslaco, Texas 78599, USA
| | - Greg W Douhan
- Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
| | - Susan E Halbert
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, P.O. Box 147100, Gainesville, Florida 32614, USA
| | - Manjunath L Keremane
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, California 92507, USA
| | - Richard F Lee
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, California 92507, USA
| | - Georgios Vidalakis
- Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
| | - Hongwei Zhao
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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Hu J, Akula N, Wang N. Development of a Microemulsion Formulation for Antimicrobial SecA Inhibitors. PLoS One 2016; 11:e0150433. [PMID: 26963811 PMCID: PMC4786163 DOI: 10.1371/journal.pone.0150433] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 02/13/2016] [Indexed: 11/19/2022] Open
Abstract
In our previous study, we have identified five antimicrobial small molecules via structure based design, which inhibit SecA of Candidatus Liberibacter asiaticus (Las). SecA is a critical protein translocase ATPase subunit and is involved in pre-protein translocation across and integration into the cellular membrane in bacteria. In this study, eleven compounds were identified using similarity search method based on the five lead SecA inhibitors identified previously. The identified SecA inhibitors have poor aqueous solubility. Thus a microemulsion master mix (MMX) was developed to address the solubility issue and for application of the antimicrobials. MMX consists of N-methyl-2-pyrrolidone and dimethyl sulfoxide as solvent and co-solvent, as well as polyoxyethylated castor oil, polyalkylene glycol, and polyoxyethylene tridecyl ether phosphate as surfactants. MMX has significantly improved the solubility of SecA inhibitors and has no or little phytotoxic effects at concentrations less than 5.0% (v/v). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the SecA inhibitors and streptomycin against eight bacteria including Agrobacterium tumefaciens, Liberibacter crescens, Rhizobium etli, Bradyrhizobium japonicum, Mesorhizobium loti, and Sinorhizobium meliloti phylogenetically related to Las were determined using the broth microdilution method. MIC and MBC results showed that the 16 SecA inhibitors have antibacterial activities comparable to that of streptomycin. Overall, we have identified 11 potent SecA inhibitors using similarity search method. We have developed a microemulsion formulation for SecA inhibitors which improved the antimicrobial activities of SecA inhibitors.
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Affiliation(s)
- Jiahuai Hu
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Nagaraju Akula
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Nian Wang
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
- * E-mail:
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Jenkins DA, Hall DG, Goenaga R. Diaphorina citri (Hemiptera: Liviidae) Abundance in Puerto Rico Declines with Elevation. JOURNAL OF ECONOMIC ENTOMOLOGY 2015; 108:252-258. [PMID: 26470127 DOI: 10.1093/jee/tou050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/21/2014] [Indexed: 06/05/2023]
Abstract
Diaphorina citri Kuwayama is the primary vector of Huanglongbing, the most devastating disease of citrus. D. citri populations in Puerto Rico were monitored with yellow sticky traps on citrus trees or other psyllid host plants at different elevations, ranging from 10 to 880 m above sea level. Trapping was conducted in March through May of 2013 and 2014 when psyllid populations usually are highest. Population levels of D. citri, based on the trapping data, varied among the sites, and there was a strong trend in both years for decreasing psyllid abundance with increased elevation based on the number of psyllids captured on traps and the proportion of trees shown to be infested. No psyllids were collected at an elevation of >600 m. Reduced populations at higher elevations could be a consequence of differences in temperature, air pressure, oxygen levels, ultraviolet light, or other factors alone or in combination. We discuss our results as they pertain to management of D. citri and Huanglongbing.
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Affiliation(s)
- David A Jenkins
- USDA-ARS-Tropical Agriculture Research Station, 2200 Ave. P.A. Campos, Ste. 201, Mayaguez, PR 00680. Corresponding author, e-mail:
| | - David G Hall
- USDA-ARS Horticultural Research Laboratory, 2100 South Rock Rd., Fort Pierce, FL 34945
| | - Ricardo Goenaga
- USDA-ARS-Tropical Agriculture Research Station, 2200 Ave. P.A. Campos, Ste. 201, Mayaguez, PR 00680
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Monteiro F, Romeiras MM, Figueiredo A, Sebastiana M, Baldé A, Catarino L, Batista D. Tracking cashew economically important diseases in the West African region using metagenomics. FRONTIERS IN PLANT SCIENCE 2015; 6:482. [PMID: 26175748 PMCID: PMC4485029 DOI: 10.3389/fpls.2015.00482] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/15/2015] [Indexed: 05/05/2023]
Abstract
During the last decades, agricultural land-uses in West Africa were marked by dramatic shifts in the coverage of individual crops. Nowadays, cashew (Anacardium occidentale L.) is one of the most export-oriented horticulture crops, notably in Guinea-Bissau. Relying heavily on agriculture to increase their income, developing countries have been following a strong trend of moving on from traditional farming systems toward commercial production. Emerging infectious diseases, driven either by adaptation to local conditions or inadvertent importation of plant pathogens, are able to cause tremendous cashew production losses, with economic and social impact of which, in developing countries is often underestimated. Presently, plant genomics with metagenomics as an emergent tool, presents an enormous potential to better characterize diseases by providing extensive knowledge on plant pathogens at a large scale. In this perspective, we address metagenomics as a promising genomic tool to identify cashew fungal associated diseases as well as to discriminate the causal pathogens, aiming at obtaining tools to help design effective strategies for disease control and thus promote the sustainable production of cashew in West African Region.
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Affiliation(s)
- Filipa Monteiro
- BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Maria M. Romeiras
- BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Tropical Research Institute, Lisboa, Portugal
| | - Andreia Figueiredo
- BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Mónica Sebastiana
- BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Aladje Baldé
- Instituto Piaget da Guiné-Bissau, Bissau, Guiné-Bissau
| | - Luís Catarino
- Tropical Research Institute, Lisboa, Portugal
- Centre in Biodiversity and Genetic Resources, Universidade do Porto, Vairão, Portugal
| | - Dora Batista
- Tropical Research Institute, Lisboa, Portugal
- cE3c - Centre for Ecology, Evolution and Environmental Changes,Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- *Correspondence: Dora Batista, Tropical Research Institute, Centro de Investigação das Ferrugens do Cafeeiro, Quinta do Marquês, 2784-505 Oeiras, Portugal; Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande,1749-016 Lisboa, Portugal,
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Coletta-Filho HD, Daugherty MP, Ferreira C, Lopes JRS. Temporal progression of 'Candidatus Liberibacter asiaticus' infection in citrus and acquisition efficiency by Diaphorina citri. PHYTOPATHOLOGY 2014; 104:416-21. [PMID: 24620723 DOI: 10.1094/phyto-06-13-0157-r] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Over the last decade, the plant disease huanglongbing (HLB) has emerged as a primary threat to citrus production worldwide. HLB is associated with infection by phloem-limited bacteria ('Candidatus Liberibacter' spp.) that are transmitted by the Asian citrus psyllid, Diaphorina citri. Transmission efficiency varies with vector-related aspects (e.g., developmental stage and feeding periods) but there is no information on the effects of host-pathogen interactions. Here, acquisition efficiency of 'Candidatus Liberibacter asiaticus' by D. citri was evaluated in relation to temporal progression of infection and pathogen titer in citrus. We graft inoculated sweet orange trees with 'Ca. L. asiaticus'; then, at different times after inoculation, we inspected plants for HLB symptoms, measured bacterial infection levels (i.e., titer or concentration) in plants, and measured acquisition by psyllid adults that were confined on the trees. Plant infection levels increased rapidly over time, saturating at uniformly high levels (≈10(8) copy number of 16S ribosomal DNA/g of plant tissue) near 200 days after inoculation-the same time at which all infected trees first showed disease symptoms. Pathogen acquisition by vectors was positively associated with plant infection level and time since inoculation, with acquisition occurring as early as the first measurement, at 60 days after inoculation. These results suggest that there is ample potential for psyllids to acquire the pathogen from trees during the asymptomatic phase of infection. If so, this could limit the effectiveness of tree rouging as a disease management tool and would likely explain the rapid spread observed for this disease in the field.
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Kogenaru S, Yan Q, Riera N, Roper MC, Deng X, Ebert TA, Rogers M, Irey ME, Pietersen G, Rush CM, Wang N. Repertoire of novel sequence signatures for the detection of Candidatus Liberibacter asiaticus by quantitative real-time PCR. BMC Microbiol 2014; 14:39. [PMID: 24533511 PMCID: PMC4015361 DOI: 10.1186/1471-2180-14-39] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 02/12/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Huanglongbing (HLB) or citrus greening is a devastating disease of citrus. The gram-negative bacterium Candidatus Liberibacter asiaticus (Las) belonging to the α-proteobacteria is responsible for HLB in North America as well as in Asia. Currently, there is no cure for this disease. Early detection and quarantine of Las-infected trees are important management strategies used to prevent HLB from invading HLB-free citrus producing regions. Quantitative real-time PCR (qRT-PCR) based molecular diagnostic assays have been routinely used in the detection and diagnosis of Las. The oligonucleotide primer pairs based on conserved genes or regions, which include 16S rDNA and the β-operon, have been widely employed in the detection of Las by qRT-PCR. The availability of whole genome sequence of Las now allows the design of primers beyond the conserved regions for the detection of Las explicitly. RESULTS We took a complimentary approach by systematically screening the genes in a genome-wide fashion, to identify the unique signatures that are only present in Las by an exhaustive sequence based similarity search against the nucleotide sequence database. Our search resulted in 34 probable unique signatures. Furthermore, by designing the primer pair specific to the identified signatures, we showed that most of our primer sets are able to detect Las from the infected plant and psyllid materials collected from the USA and China by qRT-PCR. Overall, 18 primer pairs of the 34 are found to be highly specific to Las with no cross reactivity to the closely related species Ca. L. americanus (Lam) and Ca. L. africanus (Laf). CONCLUSIONS We have designed qRT-PCR primers based on Las specific genes. Among them, 18 are suitable for the detection of Las from Las-infected plant and psyllid samples. The repertoire of primers that we have developed and characterized in this study enhanced the qRT-PCR based molecular diagnosis of HLB.
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Affiliation(s)
- Sunitha Kogenaru
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred 33850, USA
- Present address: Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0676, USA
| | - Qing Yan
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred 33850, USA
| | - Nadia Riera
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred 33850, USA
| | - M Caroline Roper
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - Xiaoling Deng
- Department of Plant Pathology, South China Agricultural University, Guangzhou, Guangdong, P. R. China
| | - Timothy A Ebert
- Department of Entomology and Nematology, Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred 33850, USA
| | - Michael Rogers
- Department of Entomology and Nematology, Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred 33850, USA
| | | | - Gerhard Pietersen
- Department of Microbiology & Plant Pathology, ARC-Plant Protection Research Institute, University of Pretoria, Pretoria, South Africa
| | - Charles M Rush
- Texas A&M AgriLife Research and Extension Center, Texas A&M University, Amarillo, USA
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred 33850, USA
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Pitino M, Hoffman MT, Zhou L, Hall DG, Stocks IC, Duan Y. The phloem-sap feeding mealybug (Ferrisia virgata) carries 'Candidatus Liberibacter asiaticus' populations that do not cause disease in host plants. PLoS One 2014; 9:e85503. [PMID: 24465578 PMCID: PMC3896372 DOI: 10.1371/journal.pone.0085503] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/27/2013] [Indexed: 11/25/2022] Open
Abstract
'Candidatus Liberibacter asiaticus' (Las) is the primary causal agent of huanglongbing (HLB), the most devastating disease of citrus worldwide. There are three known insect vectors of the HLB-associated bacteria, and all are members of the Hemiptera: Diaphorina citri (Psyllidae), Trioza erytreae (Triozidae), and Cacopsylla (Psylla) citrisuga (Psyllidae). In this study, we found that another hemipteran, the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae), was able to acquire and retain Las bacteria. The bacterial titers were positively correlated with the feeding acquisition time on Las-infected leaf discs, with a two-weeks feeding period resulting in Ct values ranging from 23.1 to 36.1 (8.24 × 10(7) to 1.07 × 10(4) Las cells per mealybug). We further discovered that the prophage/phage populations of Las in the mealybugs were different from those of Las in psyllids based on Las prophage-specific molecular markers: infected psyllids harbored the Las populations with prophage/phage FP1 and FP2, while infected mealybugs carried the Las populations with the iFP3 being the dominant prophage/phage. As in the psyllids, Las bacteria were shown to move through the insect gut wall to the salivary glands after being ingested by the mealybug based on a time-course quantitative polymerase chain reaction (qPCR) assay of the dissected digestive systems. However, Las populations transmitted by the mealybugs did not cause disease in host plants. This is the first evidence of genetic difference among Las populations harbored by different insect vectors and difference among Las populations with respect to whether or not they cause disease in host plants.
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Affiliation(s)
- Marco Pitino
- United States Horticultural Research Laboratory, United States Department of Agriculture-Agriculture Research Service, Fort Pierce, Florida, United States of America
| | - Michele T. Hoffman
- United States Horticultural Research Laboratory, United States Department of Agriculture-Agriculture Research Service, Fort Pierce, Florida, United States of America
| | - Lijuan Zhou
- United States Horticultural Research Laboratory, United States Department of Agriculture-Agriculture Research Service, Fort Pierce, Florida, United States of America
- University of Florida, Institute of Food and Agricultural Sciences-Indian River Research and Education Center, Fort Pierce, Florida, United States of America
| | - David G. Hall
- United States Horticultural Research Laboratory, United States Department of Agriculture-Agriculture Research Service, Fort Pierce, Florida, United States of America
| | - Ian C. Stocks
- Florida Department of Agriculture and Consumer Services-Drug Policy Institute, Gainesville, Florida, United States of America
| | - Yongping Duan
- United States Horticultural Research Laboratory, United States Department of Agriculture-Agriculture Research Service, Fort Pierce, Florida, United States of America
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Parker JK, Wisotsky SR, Johnson EG, Hijaz FM, Killiny N, Hilf ME, De La Fuente L. Viability of 'Candidatus Liberibacter asiaticus' prolonged by addition of citrus juice to culture medium. PHYTOPATHOLOGY 2014; 104:15-26. [PMID: 23883155 DOI: 10.1094/phyto-05-13-0119-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Huanglongbing, or citrus greening disease, is associated with infection by the phloem-limited bacterium 'Candidatus Liberibacter asiaticus'. Infection with 'Ca. L. asiaticus' is incurable; therefore, knowledge regarding 'Ca. L. asiaticus' biology and pathogenesis is essential to develop a treatment. However, 'Ca. L. asiaticus' cannot currently be successfully cultured, limiting its study. To gain insight into the conditions conducive for growth of 'Ca. L. asiaticus' in vitro, 'Ca. L. asiaticus' inoculum obtained from seed of fruit from infected pomelo trees (Citrus maxima 'Mato Buntan') was added to different media, and cell viability was monitored for up to 2 months using quantitative polymerase chain reaction in conjunction with ethidium monoazide. Media tested included one-third King's B (K), K with 50% juice from the infected fruit, K with 50% commercially available grapefruit juice, and 100% commercially available grapefruit juice. Results show that juice-containing media dramatically prolong viability compared with K in experiments reproduced during 2 years using different juice sources. Furthermore, biofilm formed at the air-liquid interface of juice cultures contained 'Ca. L. asiaticus' cells, though next-generation sequencing indicated that other bacterial genera were predominant. Chemical characterization of the media was conducted to discuss possible factors sustaining 'Ca. L. asiaticus' viability in vitro, which will contribute to future development of a culture medium for 'Ca. L. asiaticus'.
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Zhang M, Powell CA, Benyon LS, Zhou H, Duan Y. Deciphering the bacterial microbiome of citrus plants in response to 'Candidatus Liberibacter asiaticus'-infection and antibiotic treatments. PLoS One 2013; 8:e76331. [PMID: 24250784 PMCID: PMC3826729 DOI: 10.1371/journal.pone.0076331] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/23/2013] [Indexed: 11/18/2022] Open
Abstract
The bacterial microbiomes of citrus plants were characterized in response to 'Candidatus Liberibacter asiaticus' (Las)-infection and treatments with ampicillin (Amp) and gentamicin (Gm) by Phylochip-based metagenomics. The results revealed that 7,407 of over 50,000 known Operational Taxonomic Units (OTUs) in 53 phyla were detected in citrus leaf midribs using the PhyloChip™ G3 array, of which five phyla were dominant, Proteobacteria (38.7%), Firmicutes (29.0%), Actinobacteria (16.1%), Bacteroidetes (6.2%) and Cyanobacteria (2.3%). The OTU62806, representing 'Candidatus Liberibacter', was present with a high titer in the plants graft-inoculated with Las-infected scions treated with Gm at 100 mg/L and in the water-treated control (CK1). However, the Las bacterium was not detected in the plants graft-inoculated with Las-infected scions treated with Amp at 1.0 g/L or in plants graft-inoculated with Las-free scions (CK2). The PhyloChip array demonstrated that more OTUs, at a higher abundance, were detected in the Gm-treated plants than in the other treatment and the controls. Pairwise comparisons indicated that 23 OTUs from the Achromobacter spp. and 12 OTUs from the Methylobacterium spp. were more abundant in CK2 and CK1, respectively. Ten abundant OTUs from the Stenotrophomonas spp. were detected only in the Amp-treatment. These results provide new insights into microbial communities that may be associated with the progression of citrus huanglongbing (HLB) and the potential effects of antibiotics on the disease and microbial ecology.
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Affiliation(s)
- Muqing Zhang
- Indian River Research and Education Center, IFAS-UF, Fort Pierce, Florida, United States of America
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
- State Key Lab for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, Guangxi, China
| | - Charles A. Powell
- Indian River Research and Education Center, IFAS-UF, Fort Pierce, Florida, United States of America
| | - Lesley S. Benyon
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
| | - Hui Zhou
- State Key Lab for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, Guangxi, China
| | - Yongping Duan
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
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Martinelli F, Reagan RL, Uratsu SL, Phu ML, Albrecht U, Zhao W, Davis CE, Bowman KD, Dandekar AM. Gene regulatory networks elucidating huanglongbing disease mechanisms. PLoS One 2013; 8:e74256. [PMID: 24086326 PMCID: PMC3783430 DOI: 10.1371/journal.pone.0074256] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/29/2013] [Indexed: 12/02/2022] Open
Abstract
Next-generation sequencing was exploited to gain deeper insight into the response to infection by Candidatus liberibacter asiaticus (CaLas), especially the immune disregulation and metabolic dysfunction caused by source-sink disruption. Previous fruit transcriptome data were compared with additional RNA-Seq data in three tissues: immature fruit, and young and mature leaves. Four categories of orchard trees were studied: symptomatic, asymptomatic, apparently healthy, and healthy. Principal component analysis found distinct expression patterns between immature and mature fruits and leaf samples for all four categories of trees. A predicted protein - protein interaction network identified HLB-regulated genes for sugar transporters playing key roles in the overall plant responses. Gene set and pathway enrichment analyses highlight the role of sucrose and starch metabolism in disease symptom development in all tissues. HLB-regulated genes (glucose-phosphate-transporter, invertase, starch-related genes) would likely determine the source-sink relationship disruption. In infected leaves, transcriptomic changes were observed for light reactions genes (downregulation), sucrose metabolism (upregulation), and starch biosynthesis (upregulation). In parallel, symptomatic fruits over-expressed genes involved in photosynthesis, sucrose and raffinose metabolism, and downregulated starch biosynthesis. We visualized gene networks between tissues inducing a source-sink shift. CaLas alters the hormone crosstalk, resulting in weak and ineffective tissue-specific plant immune responses necessary for bacterial clearance. Accordingly, expression of WRKYs (including WRKY70) was higher in fruits than in leaves. Systemic acquired responses were inadequately activated in young leaves, generally considered the sites where most new infections occur.
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Affiliation(s)
- Federico Martinelli
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
- Dipartimento di Sistemi Agro-ambientali, Università degli Studi di Palermo, Palermo, Italy
| | - Russell L. Reagan
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Sandra L. Uratsu
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - My L. Phu
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Ute Albrecht
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America
| | - Weixiang Zhao
- Department of Mechanical and Aerospace Engineering, University of California Davis, Davis, California, United States of America
| | - Cristina E. Davis
- Department of Mechanical and Aerospace Engineering, University of California Davis, Davis, California, United States of America
| | - Kim D. Bowman
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America
| | - Abhaya M. Dandekar
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
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Graham JH, Johnson EG, Gottwald TR, Irey MS. Presymptomatic Fibrous Root Decline in Citrus Trees Caused by Huanglongbing and Potential Interaction with Phytophthora spp. PLANT DISEASE 2013; 97:1195-1199. [PMID: 30722426 DOI: 10.1094/pdis-01-13-0024-re] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Huanglongbing (HLB), associated with 'Candidatus Liberibacter asiaticus', was first detected in Florida in late 2005 and is now widely distributed throughout the commercial citrus-growing regions. In recent seasons, concurrent with freeze and drought episodes, symptomatic HLB-infected trees were much more affected by the extremes of temperature and moisture than trees without HLB. Symptoms exhibited by the stressed trees were excessive leaf loss and premature fruit drop even when HLB-infected trees were managed with good nutritional and irrigation practices recommended to support health of HLB-affected trees. This stress intolerance may be due to a loss of fibrous roots. To assess root status of HLB-infected trees on 'Swingle' citrumelo rootstock (Citrus paradisi × Poncirus trifoliata), blocks of 2,307 3-year-old 'Hamlin' orange trees and 2,693 4-year-old 'Valencia' orange trees were surveyed visually and with a real-time polymerase chain reaction (PCR) assay to determine 'Ca. L. asiaticus' infection status. The incidence of 'Ca. L. asiaticus'-infected trees (presymptomatic: 'Ca. L. asiaticus'+, visually negative; and symptomatic: 'Ca. L. asiaticus'+, visually positive) trees was 89% for the Hamlin block and 88% for the Valencia block. 'Ca. L. asiaticus'+ trees had 30 and 37% lower fibrous root mass density for presymptomatic and symptomatic trees, respectively, compared with 'Ca. L. asiaticus'- trees. In a second survey, 10- to 25-year-old Valencia trees on Swingle citrumelo or 'Carrizo' citrange (C. sinensis (L.) × P. trifoliata) rootstock were sampled within 3 to 6 months after identification of visual HLB status as symptomatic ('Ca. L. asiaticus'+, visually positive) or nonsymptomatic ('Ca. L. asiaticus'-, visually negative) in orchards located in the central ridge, south-central, and southwest flatwoods. Pairs of HLB symptomatic and nonsymptomatic trees were evaluated for PCR status, fibrous root mass density, and Phytophthora nicotianae propagules in the rhizosphere soil. 'Ca. L. asiaticus'+ trees had 27 to 40% lower fibrous root mass density and, in one location, higher P. nicotianae per root but Phytophthora populations per cubic centimeter of soil were high on both 'Ca. L. asiaticus'+ and 'Ca. L. asiaticus'- trees. Fibrous root loss from HLB damage interacted with P. nicotianae depending on orchard location and time of year.
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Affiliation(s)
- J H Graham
- University of Florida, Citrus Research and Education Center, Lake Alfred 33850
| | - E G Johnson
- University of Florida, Citrus Research and Education Center, Lake Alfred 33850
| | | | - M S Irey
- U.S. Sugar Corp., Clewiston, FL 33440
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Morey M, Fernández-Marmiesse A, Castiñeiras D, Fraga JM, Couce ML, Cocho JA. A glimpse into past, present, and future DNA sequencing. Mol Genet Metab 2013; 110:3-24. [PMID: 23742747 DOI: 10.1016/j.ymgme.2013.04.024] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/30/2013] [Accepted: 04/30/2013] [Indexed: 12/21/2022]
Abstract
Current advances in DNA sequencing technologies are dropping down sequencing cost while increasing throughput at a pace never shown before. Past-decade great milestones, as the establishment of a reference human genome (amongst others) and large-scale human genetic variation study in the 1000 Genome project are, in conjunction with the use of these techniques, triggering advances in many areas of basic and applied science. These tools, stored in and combined with the vast amount of information present in biological online databases are, with the use of automated interpretation and analysis tools, allowing the fulfillment of increasingly ambitious studies in many areas and also are democratizing the access to information, interpretation and technologies, being the first opportunity for researchers to assess the influence of genetics in complex events as multifactorial diseases, evolutionary studies, metagenomics, transcriptomics, etc. In this review, we present the current state of the art of these technologies, focusing on second generation sequencing, from sample and library preparation to sequencing chemistries and bioinformatic software available for final data analysis and visualisation, with its possible applications. We also make an overview of first and third generation, due to its historical importance and for being the upcoming future tools for genetic analysis, respectively.
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Affiliation(s)
- Marcos Morey
- Unidad de Diagnóstico y Tratamiento de Enfermedades Metabólicas Congénitas, Hospital Clínico Universitario de Santiago, A Choupana s/n, 15706 Santiago de Compostela, Spain.
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Wang N, Trivedi P. Citrus huanglongbing: a newly relevant disease presents unprecedented challenges. PHYTOPATHOLOGY 2013; 103:652-65. [PMID: 23441969 DOI: 10.1094/phyto-12-12-0331-rvw] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Citrus huanglongbing (HLB) is one of the oldest citrus diseases and has been known for over a century. HLB is caused by 'Candidatus Liberibacter' spp. that are phloem-limited, fastidious α-proteobacteria and infect hosts in different Kingdoms (i.e., Animalia and Plantae). When compared with well-characterized, cultivatable plant-pathogenic Gram-negative bacteria, the interactions of uncultured insect-vectored plant-pathogenic bacteria, including 'Ca. Liberibacter' spp., with their hosts remain poorly understood. 'Ca. Liberibacter' spp. have been known to cause HLB, which has been rapidly spreading worldwide, resulting in dramatic economic losses. HLB presents an unprecedented challenge to citrus production. In this review, we focus on the most recent research on citrus, 'Candidatus Liberibacter asiaticus', and psyllid interactions, specifically considering the following topics: evolutionary relationships among 'Ca. Liberibacter' spp., genetic diversity, host range, genome analysis, transmission, virulence mechanisms, and the ecological importance of HLB. Currently, no efficient management strategy is available to control HLB, although some promising progress has been made. Further studies are needed to understand citrus, 'Ca. L. asiaticus', and psyllid interactions to design innovative management strategies. Although HLB has been problematic for over a century, we can only win the battle against HLB with a coordinated and deliberate effort by the citrus industry, citrus growers, researchers, legislatures, and governments.
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Affiliation(s)
- Nian Wang
- Cirtrus Research Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred 33850, USA.
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Yan Q, Sreedharan A, Wei S, Wang J, Pelz-Stelinski K, Folimonova S, Wang N. Global gene expression changes in Candidatus Liberibacter asiaticus during the transmission in distinct hosts between plant and insect. MOLECULAR PLANT PATHOLOGY 2013; 14:391-404. [PMID: 23336388 PMCID: PMC6638839 DOI: 10.1111/mpp.12015] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Huanglongbing (HLB) or citrus greening disease is a destructive disease of citrus worldwide, which is associated with Candidatus Liberibacter asiaticus. This phloem-limited fastidious pathogen is transmitted by the Asian citrus psyllid, Diaphorina citri, and appears to be an intracellular pathogen that maintains an intimate association with the psyllid or the plant throughout its life cycle. The molecular basis of the interaction of this pathogen with its hosts is not well understood. We hypothesized that, during infection, Ca. L. asiaticus differentially expresses the genes critical for its survival and/or pathogenicity in either host. To test this hypothesis, quantitative reverse transcription-polymerase chain reaction was performed to compare the gene expression of Ca. L. asiaticus in planta and in psyllid. Overall, 381 genes were analysed for their gene expression in planta and in psyllid. Among them, 182 genes were up-regulated in planta compared with in psyllid (P < 0.05), 16 genes were up-regulated in psyllid (P < 0.05) and 183 genes showed no statistically significant difference (P ≥ 0.05) in expression between in planta and in psyllid. Our study indicates that the expression of the Ca. L. asiaticus genes involved in transcriptional regulation, transport system, secretion system, flagella assembly, metabolic pathway and stress resistance are changed significantly in a host-specific manner to adapt to the distinct environments of plant and insect. To our knowledge, this is the first large-scale study to evaluate the differential expression of Ca. L. asiaticus genes in a plant host and its insect vector.
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Affiliation(s)
- Qing Yan
- Department of Microbiology and Cell Science, Citrus Research and Education Center, IFAS, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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Mafra V, Martins PK, Francisco CS, Ribeiro-Alves M, Freitas-Astúa J, Machado MA. Candidatus Liberibacter americanus induces significant reprogramming of the transcriptome of the susceptible citrus genotype. BMC Genomics 2013; 14:247. [PMID: 23586643 PMCID: PMC3635983 DOI: 10.1186/1471-2164-14-247] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/26/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Citrus huanglongbing (HLB) disease is caused by endogenous, phloem-restricted, Gram negative, uncultured bacteria named Candidatus Liberibacter africanus (CaLaf), Ca. L. asiaticus (CaLas), and Ca. L. americanus (CaLam), depending on the continent where the bacteria were first detected. The Asian citrus psyllid vector, Diaphorina citri, transmits CaLas and CaLam and both Liberibacter species are present in Brazil. Several studies of the transcriptional response of citrus plants manifesting HLB symptoms have been reported, but only for CaLas infection. This study evaluated the transcriptional reprogramming of a susceptible genotype of sweet orange challenged with CaLam, using a customized 385K microarray containing approximately 32,000 unigene transcripts. We analyzed global changes in gene expression of CaLam-infected leaves of sweet orange during the symptomatic stage of infection and compared the results with previously published microarray studies that used CaLas-infected plants. Twenty candidate genes were selected to validate the expression profiles in symptomatic and asymptomatic PCR-positive leaves infected with CaLas or CaLam. RESULTS The microarray analysis identified 633 differentially expressed genes during the symptomatic stage of CaLam infection. Among them, 418 (66%) were upregulated and 215 (34%) were down regulated. Five hundred and fourteen genes (81%) were orthologs of genes from Arabidopsis thaliana. Gene set enrichment analysis (GSEA) revealed that several of the transcripts encoded transporters associated with the endomembrane system, especially zinc transport. Among the most biologically relevant gene transcripts in GSEA were those related to signaling, metabolism and/or stimulus to hormones, genes responding to stress and pathogenesis, biosynthesis of secondary metabolites, oxidative stress and transcription factors belonging to different families. Real time PCR of 20 candidate genes validated the expression pattern of some genes in symptomatic and asymptomatic leaves infected with CaLam or CaLas. CONCLUSIONS Many gene transcripts and biological processes are significantly altered upon CaLam infection. Some of them had been identified in response to CaLas infection, while others had not been previously reported. These data will be useful for selecting target genes for genetic engineering to control HLB.
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Affiliation(s)
- Valéria Mafra
- Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
- Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Polyana K Martins
- Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
| | - Carolina S Francisco
- Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
| | - Marcelo Ribeiro-Alves
- Laboratório de Pesquisa em Farmacogenética / Instituto de Pesquisa Clínica Evandro Chagas (IPEC) – Fiocruz, Rio de Janeiro, Brazil
| | - Juliana Freitas-Astúa
- Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
- Embrapa Cassava & Fruits, Cruz das Almas, Bahia, Brazil
| | - Marcos A Machado
- Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
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Leonard MT, Fagen JR, Davis-Richardson AG, Davis MJ, Triplett EW. Complete genome sequence of Liberibacter crescens BT-1. Stand Genomic Sci 2012; 7:271-83. [PMID: 23408754 PMCID: PMC3569387 DOI: 10.4056/sigs.3326772] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Liberibacter crescens BT-1, a Gram-negative, rod-shaped bacterial isolate, was previously recovered from mountain papaya to gain insight on Huanglongbing (HLB) and Zebra Chip (ZC) diseases. The genome of BT-1 was sequenced at the Interdisciplinary Center for Biotechnology Research (ICBR) at the University of Florida. A finished assembly and annotation yielded one chromosome with a length of 1,504,659 bp and a G+C content of 35.4%. Comparison to other species in the Liberibacter genus, L. crescens has many more genes in thiamine and essential amino acid biosynthesis. This likely explains why L. crescens BT-1 is culturable while the known Liberibacter strains have not yet been cultured. Similar to CandidatusL. asiaticus psy62, the L. crescens BT-1 genome contains two prophage regions.
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Affiliation(s)
- Michael T Leonard
- Microbiology and Cell Science Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
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Predictive sequence analysis of the Candidatus Liberibacter asiaticus proteome. PLoS One 2012; 7:e41071. [PMID: 22815919 PMCID: PMC3399792 DOI: 10.1371/journal.pone.0041071] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 06/18/2012] [Indexed: 01/05/2023] Open
Abstract
Candidatus Liberibacter asiaticus (Ca. L. asiaticus) is a parasitic Gram-negative bacterium that is closely associated with Huanglongbing (HLB), a worldwide citrus disease. Given the difficulty in culturing the bacterium and thus in its experimental characterization, computational analyses of the whole Ca. L. asiaticus proteome can provide much needed insights into the mechanisms of the disease and guide the development of treatment strategies. In this study, we applied state-of-the-art sequence analysis tools to every Ca. L. asiaticus protein. Our results are available as a public website at http://prodata.swmed.edu/liberibacter_asiaticus/. In particular, we manually curated the results to predict the subcellular localization, spatial structure and function of all Ca. L. asiaticus proteins (http://prodata.swmed.edu/liberibacter_asiaticus/curated/). This extensive information should facilitate the study of Ca. L. asiaticus proteome function and its relationship to disease. Pilot studies based on the information from our website have revealed several potential virulence factors, discussed herein.
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50
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Wirth R, Kovács E, Maróti G, Bagi Z, Rákhely G, Kovács KL. Characterization of a biogas-producing microbial community by short-read next generation DNA sequencing. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:41. [PMID: 22673110 PMCID: PMC3395570 DOI: 10.1186/1754-6834-5-41] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/06/2012] [Indexed: 05/20/2023]
Abstract
BACKGROUND Renewable energy production is currently a major issue worldwide. Biogas is a promising renewable energy carrier as the technology of its production combines the elimination of organic waste with the formation of a versatile energy carrier, methane. In consequence of the complexity of the microbial communities and metabolic pathways involved the biotechnology of the microbiological process leading to biogas production is poorly understood. Metagenomic approaches are suitable means of addressing related questions. In the present work a novel high-throughput technique was tested for its benefits in resolving the functional and taxonomical complexity of such microbial consortia. RESULTS It was demonstrated that the extremely parallel SOLiD™ short-read DNA sequencing platform is capable of providing sufficient useful information to decipher the systematic and functional contexts within a biogas-producing community. Although this technology has not been employed to address such problems previously, the data obtained compare well with those from similar high-throughput approaches such as 454-pyrosequencing GS FLX or Titanium. The predominant microbes contributing to the decomposition of organic matter include members of the Eubacteria, class Clostridia, order Clostridiales, family Clostridiaceae. Bacteria belonging in other systematic groups contribute to the diversity of the microbial consortium. Archaea comprise a remarkably small minority in this community, given their crucial role in biogas production. Among the Archaea, the predominant order is the Methanomicrobiales and the most abundant species is Methanoculleus marisnigri. The Methanomicrobiales are hydrogenotrophic methanogens. Besides corroborating earlier findings on the significance of the contribution of the Clostridia to organic substrate decomposition, the results demonstrate the importance of the metabolism of hydrogen within the biogas producing microbial community. CONCLUSIONS Both microbiological diversity and the regulatory role of the hydrogen metabolism appear to be the driving forces optimizing biogas-producing microbial communities. The findings may allow a rational design of these communities to promote greater efficacy in large-scale practical systems. The composition of an optimal biogas-producing consortium can be determined through the use of this approach, and this systematic methodology allows the design of the optimal microbial community structure for any biogas plant. In this way, metagenomic studies can contribute to significant progress in the efficacy and economic improvement of biogas production.
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Affiliation(s)
- Roland Wirth
- Department of Biotechnology, University of Szeged, Középfasor 52, Szeged, H-6726, Hungary
| | - Etelka Kovács
- Department of Biotechnology, University of Szeged, Középfasor 52, Szeged, H-6726, Hungary
| | - Gergely Maróti
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, H-6726, Hungary
- Bay Zoltán Nonprofit Research Ltd, Derkovits fasor 2, Szeged, H-6726, Hungary
| | - Zoltán Bagi
- Department of Biotechnology, University of Szeged, Középfasor 52, Szeged, H-6726, Hungary
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Középfasor 52, Szeged, H-6726, Hungary
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, H-6726, Hungary
| | - Kornél L Kovács
- Department of Biotechnology, University of Szeged, Középfasor 52, Szeged, H-6726, Hungary
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, H-6726, Hungary
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