51
|
Jiménez‐Guerrero I, Pérez‐Montaño F, Da Silva GM, Wagner N, Shkedy D, Zhao M, Pizarro L, Bar M, Walcott R, Sessa G, Pupko T, Burdman S. Show me your secret(ed) weapons: a multifaceted approach reveals a wide arsenal of type III-secreted effectors in the cucurbit pathogenic bacterium Acidovorax citrulli and novel effectors in the Acidovorax genus. MOLECULAR PLANT PATHOLOGY 2020; 21:17-37. [PMID: 31643123 PMCID: PMC6913199 DOI: 10.1111/mpp.12877] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The cucurbit pathogenic bacterium Acidovorax citrulli requires a functional type III secretion system (T3SS) for pathogenicity. In this bacterium, as with Xanthomonas and Ralstonia spp., an AraC-type transcriptional regulator, HrpX, regulates expression of genes encoding T3SS components and type III-secreted effectors (T3Es). The annotation of a sequenced A. citrulli strain revealed 11 T3E genes. Assuming that this could be an underestimation, we aimed to uncover the T3E arsenal of the A. citrulli model strain, M6. Thorough sequence analysis revealed 51 M6 genes whose products are similar to known T3Es. Furthermore, we combined machine learning and transcriptomics to identify novel T3Es. The machine-learning approach ranked all A. citrulli M6 genes according to their propensity to encode T3Es. RNA-Seq revealed differential gene expression between wild-type M6 and a mutant defective in HrpX: 159 and 28 genes showed significantly reduced and increased expression in the mutant relative to wild-type M6, respectively. Data combined from these approaches led to the identification of seven novel T3E candidates that were further validated using a T3SS-dependent translocation assay. These T3E genes encode hypothetical proteins that seem to be restricted to plant pathogenic Acidovorax species. Transient expression in Nicotiana benthamiana revealed that two of these T3Es localize to the cell nucleus and one interacts with the endoplasmic reticulum. This study places A. citrulli among the 'richest' bacterial pathogens in terms of T3E cargo. It also revealed novel T3Es that appear to be involved in the pathoadaptive evolution of plant pathogenic Acidovorax species.
Collapse
Affiliation(s)
- Irene Jiménez‐Guerrero
- Department of Plant Pathology and MicrobiologyThe Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of JerusalemRehovotIsrael
| | - Francisco Pérez‐Montaño
- Department of Plant Pathology and MicrobiologyThe Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of JerusalemRehovotIsrael
- Department of MicrobiologyUniversity of SevilleSevilleSpain
| | - Gustavo Mateus Da Silva
- Department of Plant Pathology and MicrobiologyThe Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of JerusalemRehovotIsrael
| | - Naama Wagner
- The School of Molecular Cell Biology and BiotechnologyThe George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Dafna Shkedy
- The School of Molecular Cell Biology and BiotechnologyThe George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Mei Zhao
- Department of Plant PathologyUniversity of GeorgiaAthensGAUSA
| | - Lorena Pizarro
- Department of Plant Pathology and Weed ResearchAgricultural Research OrganizationThe Volcani CenterBet DaganIsrael
| | - Maya Bar
- Department of Plant Pathology and Weed ResearchAgricultural Research OrganizationThe Volcani CenterBet DaganIsrael
| | - Ron Walcott
- Department of Plant PathologyUniversity of GeorgiaAthensGAUSA
| | - Guido Sessa
- School of Plant Sciences and Food SecurityThe George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Tal Pupko
- The School of Molecular Cell Biology and BiotechnologyThe George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Saul Burdman
- Department of Plant Pathology and MicrobiologyThe Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of JerusalemRehovotIsrael
| |
Collapse
|
52
|
Ge Y, Lee JH, Liu J, Yang H, Tian Y, Hu B, Zhao Y. Homologues of the RNA binding protein RsmA in Pseudomonas syringae pv. tomato DC3000 exhibit distinct binding affinities with non-coding small RNAs and have distinct roles in virulence. MOLECULAR PLANT PATHOLOGY 2019; 20:1217-1236. [PMID: 31218814 PMCID: PMC6715622 DOI: 10.1111/mpp.12823] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pseudomonas syringae pv. tomato DC3000 (PstDC3000) contains five RsmA protein homologues. In this study, four were functionally characterized, with a focus on RsmA2, RsmA3 and RsmA4. RNA electrophoretic mobility shift assays demonstrated that RsmA1 and RsmA4 exhibited similar low binding affinities to non-coding small RNAs (ncsRNAs), whereas RsmA2 and RsmA3 exhibited similar, but much higher, binding affinities to ncsRNAs. Our results showed that both RsmA2 and RsmA3 were required for disease symptom development and bacterial growth in planta by significantly affecting virulence gene expression. All four RsmA proteins, especially RsmA2 and RsmA3, influenced γ-amino butyric acid utilization and pyoverdine production to some degree, whereas RsmA2, RsmA3 and RsmA4 influenced protease activities. A single RsmA, RsmA3, played a dominant role in regulating motility. Furthermore, reverse transcription quantitative real-time PCR and western blot results showed that RsmA proteins, especially RsmA2 and RsmA3, regulated target genes and possibly other RsmA proteins at both transcriptional and translational levels. These results indicate that RsmA proteins in PstDC3000 exhibit distinct binding affinities to ncsRNAs and have distinct roles in virulence. Our results also suggest that RsmA proteins in PstDC3000 interact with each other, where RsmA2 and RsmA3 play a major role in regulating various functions in a complex manner.
Collapse
Affiliation(s)
- Yixin Ge
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and PestsNanjing Agricultural UniversityNanjing210095P. R. China
- Department of Crop SciencesUniversity of Illinois at Urbana‐ChampaignUrbanaIL61801USA
| | - Jae Hoon Lee
- Department of Crop SciencesUniversity of Illinois at Urbana‐ChampaignUrbanaIL61801USA
| | - Jun Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and PestsNanjing Agricultural UniversityNanjing210095P. R. China
- Department of Crop SciencesUniversity of Illinois at Urbana‐ChampaignUrbanaIL61801USA
| | - Ho‐wen Yang
- Department of Crop SciencesUniversity of Illinois at Urbana‐ChampaignUrbanaIL61801USA
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and PestsNanjing Agricultural UniversityNanjing210095P. R. China
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and PestsNanjing Agricultural UniversityNanjing210095P. R. China
| | - Youfu Zhao
- Department of Crop SciencesUniversity of Illinois at Urbana‐ChampaignUrbanaIL61801USA
| |
Collapse
|
53
|
Clarke CR, Timko MP, Yoder JI, Axtell MJ, Westwood JH. Molecular Dialog Between Parasitic Plants and Their Hosts. ANNUAL REVIEW OF PHYTOPATHOLOGY 2019; 57:279-299. [PMID: 31226021 DOI: 10.1146/annurev-phyto-082718-100043] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Parasitic plants steal sugars, water, and other nutrients from host plants through a haustorial connection. Several species of parasitic plants such as witchweeds (Striga spp.) and broomrapes (Orobanche and Phelipanche spp.) are major biotic constraints to agricultural production. Parasitic plants are understudied compared with other major classes of plant pathogens, but the recent availability of genomic and transcriptomic data has accelerated the rate of discovery of the molecular mechanisms underpinning plant parasitism. Here, we review the current body of knowledge of how parasitic plants sense host plants, germinate, form parasitic haustorial connections, and suppress host plant immune responses. Additionally, we assess whether parasitic plants fit within the current paradigms used to understand the molecular mechanisms of microbial plant-pathogen interactions. Finally, we discuss challenges facing parasitic plant research and propose the most urgent questions that need to be answered to advance our understanding of plant parasitism.
Collapse
Affiliation(s)
- Christopher R Clarke
- Genetic Improvement for Fruits and Vegetables Laboratory, Beltsville Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA
| | - Michael P Timko
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904, USA
| | - John I Yoder
- Department of Plant Sciences, University of California, Davis, California 95616, USA
| | - Michael J Axtell
- Department of Biology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - James H Westwood
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA;
| |
Collapse
|
54
|
Tan X, Qiu H, Li F, Cheng D, Zheng X, Wang B, Huang M, Li W, Li Y, Sang K, Song B, Du J, Chen H, Xie C. Complete Genome Sequence of Sequevar 14M Ralstonia solanacearum Strain HA4-1 Reveals Novel Type III Effectors Acquired Through Horizontal Gene Transfer. Front Microbiol 2019; 10:1893. [PMID: 31474968 PMCID: PMC6703095 DOI: 10.3389/fmicb.2019.01893] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/31/2019] [Indexed: 01/08/2023] Open
Abstract
Ralstonia solanacearum, which causes bacterial wilt in a broad range of plants, is considered a "species complex" due to its significant genetic diversity. Recently, we have isolated a new R. solanacearum strain HA4-1 from Hong'an county in Hubei province of China and identified it being phylotype I, sequevar 14M (phylotype I-14M). Interestingly, we found that it can cause various disease symptoms among different potato genotypes and display different pathogenic behavior compared to a phylogenetically related strain, GMI1000. To dissect the pathogenic mechanisms of HA4-1, we sequenced its whole genome by combined sequencing technologies including Illumina HiSeq2000, PacBio RS II, and BAC-end sequencing. Genome assembly results revealed the presence of a conventional chromosome, a megaplasmid as well as a 143 kb plasmid in HA4-1. Comparative genome analysis between HA4-1 and GMI1000 shows high conservation of the general virulence factors such as secretion systems, motility, exopolysaccharides (EPS), and key regulatory factors, but significant variation in the repertoire and structure of type III effectors, which could be the determinants of their differential pathogenesis in certain potato species or genotypes. We have identified two novel type III effectors that were probably acquired through horizontal gene transfer (HGT). These novel R. solanacearum effectors display homology to several YopJ and XopAC family members. We named them as RipBR and RipBS. Notably, the copy of RipBR on the plasmid is a pseudogene, while the other on the megaplasmid is normal. For RipBS, there are three copies located in the megaplasmid and plasmid, respectively. Our results have not only enriched the genome information on R. solanacearum species complex by sequencing the first sequevar 14M strain and the largest plasmid reported in R. solanacearum to date but also revealed the variation in the repertoire of type III effectors. This will greatly contribute to the future studies on the pathogenic evolution, host adaptation, and interaction between R. solanacearum and potato.
Collapse
Affiliation(s)
- Xiaodan Tan
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Huishan Qiu
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Feng Li
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Dong Cheng
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Xueao Zheng
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Bingsen Wang
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Mengshu Huang
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Wenhao Li
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Yanping Li
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Kangqi Sang
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Botao Song
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Juan Du
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Huilan Chen
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| | - Conghua Xie
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
- National Center for Vegetable Improvement (Central China), Wuhan, China
| |
Collapse
|
55
|
Pombo MA, Ramos RN, Zheng Y, Fei Z, Martin GB, Rosli HG. Transcriptome-based identification and validation of reference genes for plant-bacteria interaction studies using Nicotiana benthamiana. Sci Rep 2019; 9:1632. [PMID: 30733563 PMCID: PMC6367355 DOI: 10.1038/s41598-018-38247-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022] Open
Abstract
RT-qPCR is a widely used technique for the analysis of gene expression. Accurate estimation of transcript abundance relies strongly on a normalization that requires the use of reference genes that are stably expressed in the conditions analyzed. Initially, they were adopted from those used in Northern blot experiments, but an increasing number of publications highlight the need to find and validate alternative reference genes for the particular system under study. The development of high-throughput sequencing techniques has facilitated the identification of such stably expressed genes. Nicotiana benthamiana has been extensively used as a model in the plant research field. In spite of this, there is scarce information regarding suitable RT-qPCR reference genes for this species. Employing RNA-seq data previously generated from tomato plants, combined with newly generated data from N. benthamiana leaves infiltrated with Pseudomonas fluorescens, we identified and tested a set of 9 candidate reference genes. Using three different algorithms, we found that NbUbe35, NbNQO and NbErpA exhibit less variable gene expression in our pathosystem than previously used genes. Furthermore, the combined use of the first two is sufficient for robust gene expression analysis. We encourage employing these novel reference genes in future RT-qPCR experiments involving N. benthamiana and Pseudomonas spp.
Collapse
Affiliation(s)
- Marina A Pombo
- Instituto de Fisiología Vegetal, INFIVE, Universidad Nacional de La Plata, CONICET, La Plata, Buenos Aires, Argentina
| | - Romina N Ramos
- Instituto de Fisiología Vegetal, INFIVE, Universidad Nacional de La Plata, CONICET, La Plata, Buenos Aires, Argentina
| | - Yi Zheng
- Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA
| | - Zhangjun Fei
- Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA
- USDA-ARS Robert W. Holley Center for Agriculture and Health, Ithaca, NY, 14853, USA
| | - Gregory B Martin
- Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Hernan G Rosli
- Instituto de Fisiología Vegetal, INFIVE, Universidad Nacional de La Plata, CONICET, La Plata, Buenos Aires, Argentina.
| |
Collapse
|
56
|
Gao X, Ruan X, Sun Y, Wang X, Feng B. BAKing up to Survive a Battle: Functional Dynamics of BAK1 in Plant Programmed Cell Death. FRONTIERS IN PLANT SCIENCE 2019; 9:1913. [PMID: 30671069 PMCID: PMC6331536 DOI: 10.3389/fpls.2018.01913] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 12/10/2018] [Indexed: 05/12/2023]
Abstract
In plants, programmed cell death (PCD) has diverse, essential roles in vegetative and reproductive development, and in the responses to abiotic and biotic stresses. Despite the rapid progress in understanding the occurrence and functions of the diverse forms of PCD in plants, the signaling components and molecular mechanisms underlying the core PCD machinery remain a mystery. The roles of BAK1 (BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1), an essential co-receptor of multiple receptor complexes, in the regulation of immunity and development- and defense-related PCD have been well characterized. However, the ways in which BAK1 functions in mediating PCD need to be further explored. In this review, different forms of PCD in both plants and mammals are discussed. Moreover, we mainly summarize recent advances in elucidating the functions and possible mechanisms of BAK1 in controlling diverse forms of PCD. We also highlight the involvement of post-translational modifications (PTMs) of multiple signaling component proteins in BAK1-mediated PCD.
Collapse
Affiliation(s)
- Xiquan Gao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, China
| | - Xinsen Ruan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, China
| | - Yali Sun
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, China
| | - Xiue Wang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, China
| | - Baomin Feng
- Haixia Institute of Science and Technology, Fujian Agricultural and Forestry University, Fuzhou, China
| |
Collapse
|
57
|
Wang C, He X, Li Y, Wang L, Guo X, Guo X. The cotton MAPK kinase GhMPK20 negatively regulates resistance to Fusarium oxysporum by mediating the MKK4-MPK20-WRKY40 cascade. MOLECULAR PLANT PATHOLOGY 2018; 19:1624-1638. [PMID: 29098751 PMCID: PMC6637994 DOI: 10.1111/mpp.12635] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/01/2017] [Accepted: 10/27/2017] [Indexed: 05/04/2023]
Abstract
Fusarium wilt is one of the most serious diseases affecting cotton. However, the pathogenesis and mechanism by which Fusarium oxysporum overcomes plant defence responses are unclear. Here, a new group D mitogen-activated protein kinase (MAPK) gene, GhMPK20, was identified and functionally analysed in cotton. GhMPK20 expression was significantly induced by F. oxysporum. Virus-induced gene silencing (VIGS) of GhMPK20 in cotton increased the tolerance to F. oxysporum, whereas ectopic GhMPK20 overexpression in Nicotiana benthamiana reduced F. oxysporum resistance via disruption of the salicylic acid (SA)-mediated defence pathway. More importantly, an F. oxysporum-induced MAPK cascade pathway composed of GhMKK4, GhMPK20 and GhWRKY40 was identified. VIGS of GhMKK4 and GhWRKY40 also enhanced F. oxysporum resistance in cotton, and the function of GhMKK4-GhMPK20 was shown to be essential for F. oxysporum-induced GhWRKY40 expression. Together, our results indicate that the GhMKK4-GhMPK20-GhWRKY40 cascade in cotton plays an important role in the pathogenesis of F. oxysporum. This research broadens our knowledge of the negative role of the MAPK cascade in disease resistance in cotton and provides an important scientific basis for the formulation of Fusarium wilt prevention strategies.
Collapse
Affiliation(s)
- Chen Wang
- State Key Laboratory of Crop Biology, College of Life SciencesShandong Agricultural UniversityTaianShandong 271018China
| | - Xiaowen He
- State Key Laboratory of Crop BiologyShandong Agricultural UniversityTaianShandong 271018China
| | - Yuzhen Li
- State Key Laboratory of Crop Biology, College of Life SciencesShandong Agricultural UniversityTaianShandong 271018China
| | - Lijun Wang
- State Key Laboratory of Crop Biology, College of Life SciencesShandong Agricultural UniversityTaianShandong 271018China
| | - Xulei Guo
- State Key Laboratory of Crop Biology, College of Life SciencesShandong Agricultural UniversityTaianShandong 271018China
| | - Xingqi Guo
- State Key Laboratory of Crop Biology, College of Life SciencesShandong Agricultural UniversityTaianShandong 271018China
| |
Collapse
|
58
|
Clark K, Franco JY, Schwizer S, Pang Z, Hawara E, Liebrand TWH, Pagliaccia D, Zeng L, Gurung FB, Wang P, Shi J, Wang Y, Ancona V, van der Hoorn RAL, Wang N, Coaker G, Ma W. An effector from the Huanglongbing-associated pathogen targets citrus proteases. Nat Commun 2018; 9:1718. [PMID: 29712915 PMCID: PMC5928222 DOI: 10.1038/s41467-018-04140-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 04/06/2018] [Indexed: 01/29/2023] Open
Abstract
The citrus industry is facing an unprecedented challenge from Huanglongbing (HLB). All cultivars can be affected by the HLB-associated bacterium 'Candidatus Liberibacter asiaticus' (CLas) and there is no known resistance. Insight into HLB pathogenesis is urgently needed in order to develop effective management strategies. Here, we use Sec-delivered effector 1 (SDE1), which is conserved in all CLas isolates, as a molecular probe to understand CLas virulence. We show that SDE1 directly interacts with citrus papain-like cysteine proteases (PLCPs) and inhibits protease activity. PLCPs are defense-inducible and exhibit increased protein accumulation in CLas-infected trees, suggesting a role in citrus defense responses. We analyzed PLCP activity in field samples, revealing specific members that increase in abundance but remain unchanged in activity during infection. SDE1-expressing transgenic citrus also exhibit reduced PLCP activity. These data demonstrate that SDE1 inhibits citrus PLCPs, which are immune-related proteases that enhance defense responses in plants.
Collapse
Affiliation(s)
- Kelley Clark
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | | | - Simon Schwizer
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA
| | - Zhiqian Pang
- Citrus Research and Education Center, University of Florida, Lake Alfred, 33850, FL, USA
| | - Eva Hawara
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | - Thomas W H Liebrand
- Department of Plant Pathology, University of California, Davis, 95616, CA, USA
| | - Deborah Pagliaccia
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | - Liping Zeng
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA
| | - Fatta B Gurung
- Citrus Center, Texas A&M University, Weslaco, 78599, TX, USA
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside, 92521, CA, USA
| | - Jinxia Shi
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, 92521, CA, USA
| | - Veronica Ancona
- Citrus Center, Texas A&M University, Weslaco, 78599, TX, USA
| | | | - Nian Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, 33850, FL, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, 95616, CA, USA.
| | - Wenbo Ma
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA. .,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA.
| |
Collapse
|
59
|
Ma L, Djavaheri M, Wang H, Larkan NJ, Haddadi P, Beynon E, Gropp G, Borhan MH. Leptosphaeria maculans Effector Protein AvrLm1 Modulates Plant Immunity by Enhancing MAP Kinase 9 Phosphorylation. iScience 2018; 3:177-191. [PMID: 30428318 PMCID: PMC6137710 DOI: 10.1016/j.isci.2018.04.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/22/2018] [Accepted: 04/16/2018] [Indexed: 01/03/2023] Open
Abstract
Leptosphaeria maculans, the causal agent of blackleg disease in canola (Brassica napus), secretes an array of effectors into the host to overcome host defense. Here we present evidence that the L. maculans effector protein AvrLm1 functions as a virulence factor by interacting with the B. napus mitogen-activated protein (MAP) kinase 9 (BnMPK9), resulting in increased accumulation and enhanced phosphorylation of the host protein. Transient expression of BnMPK9 in Nicotiana benthamiana induces cell death, and this phenotype is enhanced in the presence of AvrLm1, suggesting that induction of cell death due to enhanced accumulation and phosphorylation of BnMPK9 by AvrLm1 supports the initiation of necrotrophic phase of L. maculans infection. Stable expression of BnMPK9 in B. napus perturbs hormone signaling, notably salicylic acid response genes, to facilitate L. maculans infection. Our findings provide evidence that a MAP kinase is directly targeted by a fungal effector to modulate plant immunity. Leptosphaeria maculans effector AvrLm1 interacts with the Brassica napus MPK9 (BnMPK9) AvrLm1 increases the accumulation and enhances the phosphorylation of BnMPK9 AvrLm1 enhances BnMPK9-dependent cell death in Nicotiana benthamiana Stable expression of BnMPK9 in B. napus facilitates L. maculans infection
Collapse
Affiliation(s)
- Lisong Ma
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Mohammad Djavaheri
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Haiyan Wang
- Center of Plant Disease and Plant Pests of Hebei Province, College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Nicholas J Larkan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; Armatus Genetics Inc., Saskatoon, SK S7J 4M2, Canada
| | - Parham Haddadi
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Elena Beynon
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Gordon Gropp
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - M Hossein Borhan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
| |
Collapse
|
60
|
Deb D, Mackey D, Opiyo SO, McDowell JM. Application of alignment-free bioinformatics methods to identify an oomycete protein with structural and functional similarity to the bacterial AvrE effector protein. PLoS One 2018; 13:e0195559. [PMID: 29641586 PMCID: PMC5895030 DOI: 10.1371/journal.pone.0195559] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/23/2018] [Indexed: 11/23/2022] Open
Abstract
Diverse plant pathogens export effector proteins to reprogram host cells. One of the most challenging goals in the molecular plant-microbe field is to functionally characterize the complex repertoires of effectors secreted by these pathogens. For bacterial pathogens, the predominant class of effectors is delivered to host cells by Type III secretion. For oomycetes, the predominant class of effectors is defined by a signal peptide that mediates secretion from the oomycete and a conserved RxLR motif. Downy mildew pathogens and Phytophthora species maintain hundreds of candidate RxLR effector genes in their genomes. Although no primary sequence similarity is evident between bacterial Type III effectors (T3Es) and oomycete RXLR effectors, some bacterial and oomycete effectors have convergently evolved to target the same host proteins. Such effectors might have evolved domains that are functionally similar but sequence-unrelated. We reasoned that alignment-free bioinformatics approaches could be useful to identify structural similarities between bacterial and oomycete effectors. To test this approach, we used partial least squares regression, alignment-free bioinformatics methods to identify effector proteins from the genome of the oomycete Hyaloperonospora arabidopsidis that are similar to the well-studied AvrE1 effector from Pseudomonas syringae. This approach identified five RxLR proteins with putative structural similarity to AvrE1. We focused on one, HaRxL23, because it is an experimentally validated effector and it is conserved between distantly related oomycetes. Several experiments indicate that HaRxL23 is functionally similar to AvrE1, including the ability to partially rescue an AvrE1 loss-of-function mutant. This study provides an example of how an alignment-free bioinformatics approach can identify functionally similar effector proteins in the absence of primary sequence similarity. This approach could be useful to identify effectors that have convergently evolved regardless of whether the shared host target is known.
Collapse
Affiliation(s)
- Devdutta Deb
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
| | - David Mackey
- Departments of Horticulture and Crop Science and Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Stephen O. Opiyo
- Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center, Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (SOO); (JMM)
| | - John M. McDowell
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
- * E-mail: (SOO); (JMM)
| |
Collapse
|
61
|
Deb D, Anderson RG, How-Yew-Kin T, Tyler BM, McDowell JM. Conserved RxLR Effectors From Oomycetes Hyaloperonospora arabidopsidis and Phytophthora sojae Suppress PAMP- and Effector-Triggered Immunity in Diverse Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:374-385. [PMID: 29106332 DOI: 10.1094/mpmi-07-17-0169-fi] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Effector proteins are exported to the interior of host cells by diverse plant pathogens. Many oomycete pathogens maintain large families of candidate effector genes, encoding proteins with a secretory leader followed by an RxLR motif. Although most of these genes are very divergent between oomycete species, several genes are conserved between Phytophthora species and Hyaloperonospora arabidopsidis, suggesting that they play important roles in pathogenicity. We describe a pair of conserved effector candidates, HaRxL23 and PsAvh73, from H. arabidopsidis and P. sojae respectively. We show that HaRxL23 is expressed early during infection of Arabidopsis. HaRxL23 triggers an ecotype-specific defense response in Arabidopsis, suggesting that it is recognized by a host surveillance protein. HaRxL23 and PsAvh73 can suppress pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) in Nicotiana benthamiana and effector-triggered immunity (ETI) in soybean. Transgenic Arabidopsis constitutively expressing HaRxL23 or PsAvh73 exhibit suppression of PTI and enhancement of bacterial and oomycete virulence. Together, our experiments demonstrate that these conserved oomycete RxLR effectors suppress PTI and ETI across diverse plant species.
Collapse
Affiliation(s)
- Devdutta Deb
- 1 Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA, 24061-0329, U.S.A
| | - Ryan G Anderson
- 1 Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA, 24061-0329, U.S.A
| | - Theresa How-Yew-Kin
- 1 Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA, 24061-0329, U.S.A
| | - Brett M Tyler
- 2 Center for Genome Research and Biocomputing, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A
| | - John M McDowell
- 1 Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA, 24061-0329, U.S.A
| |
Collapse
|
62
|
Su J, Spears BJ, Kim SH, Gassmann W. Constant vigilance: plant functions guarded by resistance proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:637-650. [PMID: 29232015 DOI: 10.1111/tpj.13798] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/27/2017] [Accepted: 11/30/2017] [Indexed: 05/09/2023]
Abstract
Unlike animals, plants do not have an adaptive immune system and have instead evolved sophisticated and multi-layered innate immune mechanisms. To overcome plant immunity, pathogens secrete a diverse array of effectors into the apoplast and virtually all cellular compartments to dampen immune signaling and interfere with plant functions. Here we describe the scope of the arms race throughout the cell and summarize various strategies used by both plants and pathogens. Through studying the ongoing evolutionary battle between plants and key pathogens, we may yet uncover potential ways to achieve the ultimate goal of engineering broad-spectrum resistant crops without affecting food quality or productivity.
Collapse
Affiliation(s)
- Jianbin Su
- Division of Plant Sciences, C.S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA
| | - Benjamin J Spears
- Division of Plant Sciences, C.S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA
| | - Sang Hee Kim
- Division of Applied Life Science (BK 21 Plus Program), Plant Molecular Biology and Biotechnology Research Center, Division of Life Science, Gyeongsang National University, Jinju, 52828, Korea
| | - Walter Gassmann
- Division of Plant Sciences, C.S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA
| |
Collapse
|
63
|
Wang J, Grubb LE, Wang J, Liang X, Li L, Gao C, Ma M, Feng F, Li M, Li L, Zhang X, Yu F, Xie Q, Chen S, Zipfel C, Monaghan J, Zhou JM. A Regulatory Module Controlling Homeostasis of a Plant Immune Kinase. Mol Cell 2018; 69:493-504.e6. [DOI: 10.1016/j.molcel.2017.12.026] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/19/2017] [Accepted: 12/22/2017] [Indexed: 10/18/2022]
|
64
|
Hassan JA, de la Torre‐Roche R, White JC, Lewis JD. Soil mixture composition alters Arabidopsis susceptibility to Pseudomonas syringae infection. PLANT DIRECT 2018; 2:e00044. [PMID: 31245710 PMCID: PMC6508533 DOI: 10.1002/pld3.44] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/08/2018] [Accepted: 01/23/2018] [Indexed: 05/25/2023]
Abstract
Pseudomonas syringae is a gram-negative bacterial pathogen that causes disease on more than 100 different plant species, including the model plant Arabidopsis thaliana. Dissection of the Arabidopsis thaliana-Pseudomonas syringae pathosystem has identified many factors that contribute to successful infection or immunity, including the genetics of the host, the genetics of the pathogen, and the environment. Environmental factors that contribute to a successful interaction can include temperature, light, and the circadian clock, as well as the soil environment. As silicon-amended Resilience soil is advertised to enhance plant health, we sought to examine the extent to which this soil might affect the behavior of the A. thaliana-P. syringae model pathosystem and to characterize the mechanisms through which these effects may occur. We found that plants grown in Si-amended Resilience soil displayed enhanced resistance to bacteria compared to plants grown in non-Si-amended Sunshine soil, and salicylic acid biosynthesis and signaling were not required for resistance. Although silicon has been shown to contribute to broad-spectrum resistance, our data indicate that silicon is not the direct cause of enhanced resistance and that the Si-amended Resilience soil has additional properties that modulate plant resistance. Our work demonstrates the importance of environmental factors, such as soil in modulating interactions between the plant and foliar pathogens, and highlights the significance of careful annotation of the environmental conditions under which plant-pathogen interactions are studied.
Collapse
Affiliation(s)
- Jana A. Hassan
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
| | | | - Jason C. White
- Department of Analytical ChemistryThe Connecticut Agricultural Experiment StationNew HavenCTUSA
| | - Jennifer D. Lewis
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
- Plant Gene Expression CenterUnited States Department of AgricultureAlbanyCAUSA
| |
Collapse
|
65
|
Büttner D. Behind the lines-actions of bacterial type III effector proteins in plant cells. FEMS Microbiol Rev 2018; 40:894-937. [PMID: 28201715 PMCID: PMC5091034 DOI: 10.1093/femsre/fuw026] [Citation(s) in RCA: 175] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/31/2016] [Accepted: 07/03/2016] [Indexed: 01/30/2023] Open
Abstract
Pathogenicity of most Gram-negative plant-pathogenic bacteria depends on the type III secretion (T3S) system, which translocates bacterial effector proteins into plant cells. Type III effectors modulate plant cellular pathways to the benefit of the pathogen and promote bacterial multiplication. One major virulence function of type III effectors is the suppression of plant innate immunity, which is triggered upon recognition of pathogen-derived molecular patterns by plant receptor proteins. Type III effectors also interfere with additional plant cellular processes including proteasome-dependent protein degradation, phytohormone signaling, the formation of the cytoskeleton, vesicle transport and gene expression. This review summarizes our current knowledge on the molecular functions of type III effector proteins with known plant target molecules. Furthermore, plant defense strategies for the detection of effector protein activities or effector-triggered alterations in plant targets are discussed.
Collapse
Affiliation(s)
- Daniela Büttner
- Genetics Department, Institute of Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| |
Collapse
|
66
|
Teper D, Girija AM, Bosis E, Popov G, Savidor A, Sessa G. The Xanthomonas euvesicatoria type III effector XopAU is an active protein kinase that manipulates plant MAP kinase signaling. PLoS Pathog 2018; 14:e1006880. [PMID: 29377937 PMCID: PMC5805367 DOI: 10.1371/journal.ppat.1006880] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/08/2018] [Accepted: 01/15/2018] [Indexed: 11/19/2022] Open
Abstract
The Gram-negative bacterium Xanthomonas euvesicatoria (Xe) is the causal agent of bacterial spot disease of pepper and tomato. Xe delivers effector proteins into host cells through the type III secretion system to promote disease. Here, we show that the Xe effector XopAU, which is conserved in numerous Xanthomonas species, is a catalytically active protein kinase and contributes to the development of disease symptoms in pepper plants. Agrobacterium-mediated expression of XopAU in host and non-host plants activated typical defense responses, including MAP kinase phosphorylation, accumulation of pathogenesis-related (PR) proteins and elicitation of cell death, that were dependent on the kinase activity of the effector. XopAU-mediated cell death was not dependent on early signaling components of effector-triggered immunity and was also observed when the effector was delivered into pepper leaves by Xanthomonas campestris pv. campestris, but not by Xe. Protein-protein interaction studies in yeast and in planta revealed that XopAU physically interacts with components of plant immunity-associated MAP kinase cascades. Remarkably, XopAU directly phosphorylated MKK2 in vitro and enhanced its phosphorylation at multiple sites in planta. Consistent with the notion that MKK2 is a target of XopAU, silencing of the MKK2 homolog or overexpression of the catalytically inactive mutant MKK2K99R in N. benthamiana plants reduced XopAU-mediated cell death and MAPK phosphorylation. Furthermore, yeast co-expressing XopAU and MKK2 displayed reduced growth and this phenotype was dependent on the kinase activity of both proteins. Together, our results support the conclusion that XopAU contributes to Xe disease symptoms in pepper plants and manipulates host MAPK signaling through phosphorylation and activation of MKK2.
Collapse
Affiliation(s)
- Doron Teper
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | | | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College, Karmiel, Israel
| | - Georgy Popov
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | - Alon Savidor
- The Nancy & Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Guido Sessa
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
67
|
Wu J, van der Burgh AM, Bi G, Zhang L, Alfano JR, Martin GB, Joosten MHAJ. The Bacterial Effector AvrPto Targets the Regulatory Coreceptor SOBIR1 and Suppresses Defense Signaling Mediated by the Receptor-Like Protein Cf-4. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:75-85. [PMID: 28876174 DOI: 10.1094/mpmi-08-17-0203-fi] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Receptor-like proteins (RLPs) and receptor-like kinases (RLKs) are cell-surface receptors that are essential for detecting invading pathogens and subsequent activation of plant defense responses. RLPs lack a cytoplasmic kinase domain to trigger downstream signaling leading to host resistance. The RLK SOBIR1 constitutively interacts with the tomato RLP Cf-4, thereby providing Cf-4 with a kinase domain. SOBIR1 is required for Cf-4-mediated resistance to strains of the fungal tomato pathogen Cladosporium fulvum that secrete the effector Avr4. Upon perception of this effector by the Cf-4/SOBIR1 complex, the central regulatory RLK SOMATIC EMBRYOGENESIS RECEPTOR KINASE 3a (SERK3a) is recruited to the complex and defense signaling is triggered. SOBIR1 is also required for RLP-mediated resistance to bacterial, fungal ,and oomycete pathogens, and we hypothesized that SOBIR1 is targeted by effectors of such pathogens to suppress host defense responses. In this study, we show that Pseudomonas syringae pv. tomato DC3000 effector AvrPto interacts with Arabidopsis SOBIR1 and its orthologs of tomato and Nicotiana benthamiana, independent of SOBIR1 kinase activity. Interestingly, AvrPto suppresses Arabidopsis SOBIR1-induced cell death in N. benthamiana. Furthermore, AvrPto compromises Avr4-triggered cell death in Cf-4-transgenic N. benthamiana, without affecting Cf-4/SOBIR1/SERK3a complex formation. Our study shows that the RLP coreceptor SOBIR1 is targeted by a bacterial effector, which results in compromised defense responses.
Collapse
Affiliation(s)
- Jinbin Wu
- 1 Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Aranka M van der Burgh
- 1 Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Guozhi Bi
- 1 Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Lisha Zhang
- 1 Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - James R Alfano
- 2 Center for Plant Science Innovation and
- 3 Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588, U.S.A
| | - Gregory B Martin
- 4 Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, U.S.A.; and
- 5 Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - Matthieu H A J Joosten
- 1 Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| |
Collapse
|
68
|
Abstract
In 2007, we reported that a phytopathogen effector directly inhibits a MAP kinase cascade. In the decade since, many more effectors have been found to inhibit MAP kinase cascades, providing not only a mechanistic understanding of pathogenesis and immunity in plants, but also the identification of previously unknown enzymes.
Collapse
Affiliation(s)
- Guozhi Bi
- The State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jian-Min Zhou
- The State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
| |
Collapse
|
69
|
Li L, Kim P, Yu L, Cai G, Chen S, Alfano JR, Zhou JM. Activation-Dependent Destruction of a Co-receptor by a Pseudomonas syringae Effector Dampens Plant Immunity. Cell Host Microbe 2017; 20:504-514. [PMID: 27736646 DOI: 10.1016/j.chom.2016.09.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 07/30/2016] [Accepted: 09/06/2016] [Indexed: 12/13/2022]
Abstract
The Arabidopsis immune receptor FLS2 and co-receptor BAK1 perceive the bacterial flagellin epitope flg22 to activate plant immunity. To prevent this response, phytopathogenic bacteria deploy a repertoire of effector proteins to perturb immune signaling. However, the effector-induced perturbation is often sensed by the host, triggering another layer of immunity. We report that the Pseudomonas syringae effector HopB1 acts as a protease to cleave immune-activated BAK1. Prior to activation, HopB1 constitutively interacts with FLS2. Upon activation by flg22, BAK1 is recruited to the FLS2-HopB1 complex and is phosphorylated at Thr455. HopB1 then specifically cleaves BAK1 between Arg297 and Gly298 to inhibit FLS2 signaling. Although perturbation of BAK1 is known to trigger increased immune responses in plants, the HopB1-mediated cleavage of BAK1 leads to enhanced virulence, but not disease resistance. This study thus reveals a virulence strategy by which a pathogen effector attacks the plant immune system with minimal host perturbation.
Collapse
Affiliation(s)
- Lei Li
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China.
| | - Panya Kim
- Center for Plant Science Innovation and School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Liping Yu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Gaihong Cai
- National Institute of Biological Sciences, Beijing 102206, China
| | - She Chen
- National Institute of Biological Sciences, Beijing 102206, China
| | - James R Alfano
- Center for Plant Science Innovation and Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588, USA
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China.
| |
Collapse
|
70
|
Liu L, Wang Y, Cui F, Fang A, Wang S, Wang J, Wei C, Li S, Sun W. The type III effector AvrXccB in Xanthomonas campestris pv. campestris targets putative methyltransferases and suppresses innate immunity in Arabidopsis. MOLECULAR PLANT PATHOLOGY 2017; 18:768-782. [PMID: 27241588 PMCID: PMC6638230 DOI: 10.1111/mpp.12435] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/17/2016] [Accepted: 05/23/2016] [Indexed: 05/04/2023]
Abstract
Xanthomonas campestris pv. campestris (Xcc) causes black rot, one of the most important diseases of brassica crops worldwide. The type III effector inventory plays important roles in the virulence and pathogenicity of the pathogen. However, little is known about the virulence function(s) of the putative type III effector AvrXccB in Xcc. Here, we investigated the immune suppression ability of AvrXccB and the possible underlying mechanisms. AvrXccB was demonstrated to be secreted in a type III secretion system-dependent manner. AvrXccB tagged with green fluorescent protein is localized to the plasma membrane in Arabidopsis, and the putative N-myristoylation motif is essential for its localization. Chemical-induced expression of AvrXccB suppresses flg22-triggered callose deposition and the oxidative burst, and promotes the in planta growth of Xcc and Pseudomonas syringae pv. tomato in transgenic Arabidopsis plants. The putative catalytic triad and plasma membrane localization of AvrXccB are required for its immunosuppressive activity. Furthermore, it was demonstrated that AvrXccB interacts with the Arabidopsis S-adenosyl-l-methionine-dependent methyltransferases SAM-MT1 and SAM-MT2. Interestingly, SAM-MT1 is not only self-associated, but also associated with SAM-MT2 in vivo. SAM-MT1 and SAM-MT2 expression is significantly induced upon stimulation of microbe-associated molecular patterns and bacterial infection. Collectively, these findings indicate that AvrXccB targets a putative methyltransferase complex and suppresses plant immunity.
Collapse
Affiliation(s)
- Lijuan Liu
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Yanping Wang
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Fuhao Cui
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Anfei Fang
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Shanzhi Wang
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Jiyang Wang
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Chao Wei
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Shuai Li
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| | - Wenxian Sun
- Department of Plant Pathology, Key Laboratory of Plant Pathology, Ministry of AgricultureChina Agricultural UniversityBeijing100193China
| |
Collapse
|
71
|
Nguyen TT, Chon TS, Kim J, Seo YS, Heo M. Comparative and bioinformatics analyses of pathogenic bacterial secretomes identified by mass spectrometry in Burkholderia species. J Microbiol 2017; 55:568-582. [PMID: 28664514 DOI: 10.1007/s12275-017-7085-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/02/2017] [Accepted: 06/12/2017] [Indexed: 10/19/2022]
Abstract
Secreted proteins (secretomes) play crucial roles during bacterial pathogenesis in both plant and human hosts. The identification and characterization of secretomes in the two plant pathogens Burkholderia glumae BGR1 and B. gladioli BSR3, which cause diseases in rice such as seedling blight, panicle blight, and grain rot, are important steps to not only understand the disease-causing mechanisms but also find remedies for the diseases. Here, we identified two datasets of secretomes in B. glumae BGR1 and B. gladioli BSR3, which consist of 118 and 111 proteins, respectively, using mass spectrometry approach and literature curation. Next, we characterized the functional properties, potential secretion pathways and sequence information properties of secretomes of two plant pathogens in a comparative analysis by various computational approaches. The ratio of potential non-classically secreted proteins (NCSPs) to classically secreted proteins (CSPs) in B. glumae BGR1 was greater than that in B. gladioli BSR3. For CSPs, the putative hydrophobic regions (PHRs) which are essential for secretion process of CSPs were screened in detail at their N-terminal sequences using hidden Markov model (HMM)-based method. Total 31 pairs of homologous proteins in two bacterial secretomes were indicated based on the global alignment (identity ≥ 70%). Our results may facilitate the understanding of the species-specific features of secretomes in two plant pathogenic Burkholderia species.
Collapse
Affiliation(s)
- Thao Thi Nguyen
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Tae-Soo Chon
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Jaehan Kim
- Department of Food and Nutrition, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Young-Su Seo
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.
| | - Muyoung Heo
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea.
| |
Collapse
|
72
|
Nakano M, Oda K, Mukaihara T. Ralstonia solanacearum novel E3 ubiquitin ligase (NEL) effectors RipAW and RipAR suppress pattern-triggered immunity in plants. MICROBIOLOGY (READING, ENGLAND) 2017; 163:992-1002. [PMID: 28708051 DOI: 10.1099/mic.0.000495] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Ralstonia solanacearum is the causal agent of bacterial wilt in solanaceous crops. This pathogen injects more than 70 effector proteins into host plant cells via the Hrp type III secretion system to cause a successful infection. However, the function of these effectors in plant cells, especially in the suppression of plant immunity, remains largely unknown. In this study, we characterized two Ralstonia solanacearum effectors, RipAW and RipAR, which share homology with the IpaH family of effectors from animal and plant pathogenic bacteria, that have a novel E3 ubiquitin ligase (NEL) domain. Recombinant RipAW and RipAR show E3 ubiquitin ligase activity in vitro. RipAW and RipAR localized to the cytoplasm of plant cells and significantly suppressed pattern-triggered immunity (PTI) responses such as the production of reactive oxygen species and the expression of defence-related genes when expressed in leaves of Nicotiana benthamiana. Mutation in the conserved cysteine residue in the NEL domain of RipAW completely abolished the E3 ubiquitin ligase activity in vitro and the ability to suppress PTI responses in plant leaves. These results indicate that RipAW suppresses plant PTI responses through the E3 ubiquitin ligase activity. Unlike other members of the IpaH family of effectors, RipAW and RipAR had no leucine-rich repeat motifs in their amino acid sequences. A conserved C-terminal region of RipAW is indispensable for PTI suppression. Transgenic Arabidopsis plants expressing RipAW and RipAR showed increased disease susceptibility, suggesting that RipAW and RipAR contribute to bacterial virulence in plants.
Collapse
Affiliation(s)
- Masahito Nakano
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
| | - Kenji Oda
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
| | - Takafumi Mukaihara
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
| |
Collapse
|
73
|
Liao D, Cao Y, Sun X, Espinoza C, Nguyen CT, Liang Y, Stacey G. Arabidopsis E3 ubiquitin ligase PLANT U-BOX13 (PUB13) regulates chitin receptor LYSIN MOTIF RECEPTOR KINASE5 (LYK5) protein abundance. THE NEW PHYTOLOGIST 2017; 214:1646-1656. [PMID: 28195333 DOI: 10.1111/nph.14472] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 01/09/2017] [Indexed: 05/21/2023]
Abstract
Long-chain chitooligosaccharides are fungal microbe-associated molecular patterns (MAMPs) that are recognized by LYSIN MOTIF RECEPTOR KINASE5 (LYK5), inducing the formation of a complex with CHITIN ELICITOR RECEPTOR KINASE1 (CERK1). Formation of this complex leads to activation of the CERK1 intracellular kinase domain and induction of plant innate immunity in Arabidopsis. We found that addition of chitooctaose induced LYK5 protein accumulation as a result of de novo gene expression and the inhibition of LYK5 protein degradation. Screening the putative E3 ligases for interaction with LYK5 identified PLANT U-BOX13 (PUB13), which complexed with LYK5, but this complex dissociated upon addition of chitooctaose. Consistent with these results, LYK5 protein abundance was higher in pub13 mutants compared with the wild type without chitooctaose treatment, while similar abundance was detected with the addition of chitooctaose. The pub13 mutants showed hypersensitivity to chitooctaose-induced rapid responses, such as the production of reactive oxygen species (ROS) and mitogen-activated protein (MAP) kinase phosphorylation, but exhibited normal responses to subsequent long-term chitooctaose treatment, such as gene expression and callose deposition. In addition, PUB13 could ubiquitinate the LYK5 kinase domain in vitro. Taken together, our results suggest an important regulatory function for the turnover of LYK5 mediated by the E3 ligase PUB13.
Collapse
Affiliation(s)
- Dehua Liao
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yangrong Cao
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xun Sun
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Catherine Espinoza
- Divisions of Plant Science and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Cuong T Nguyen
- Divisions of Plant Science and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Yan Liang
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Gary Stacey
- Divisions of Plant Science and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| |
Collapse
|
74
|
Chen T, Duan L, Zhou B, Yu H, Zhu H, Cao Y, Zhang Z. Interplay of Pathogen-Induced Defense Responses and Symbiotic Establishment in Medicago truncatula. Front Microbiol 2017; 8:973. [PMID: 28611764 PMCID: PMC5447765 DOI: 10.3389/fmicb.2017.00973] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/15/2017] [Indexed: 12/30/2022] Open
Abstract
Suppression of host innate immunity appears to be required for the establishment of symbiosis between rhizobia and host plants. In this study, we established a system that included a host plant, a bacterial pathogen and a symbiotic rhizobium to study the role of innate immunity during symbiotic interactions. A pathogenic bacterium, Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000), was shown to cause chlorosis in Medicago truncatula A17. Sinorhizobium meliloti strain Sm2011 (Sm2011) and Pst DC3000 strain alone induced similar defense responses in M. truncatula. However, when co-inoculated, Sm2011 specifically suppressed the defense responses induced by Pst DC3000, such as MAPK activation and ROS production. Inoculation with Sm2011 suppressed the transcription of defense-related genes triggered by Pst DC3000 infection, including the receptor of bacterial flagellin (FLS2), pathogenesis-related protein 10 (PR10), and the transcription factor WRKY33. Interestingly, inoculation with Pst DC3000 specifically inhibited the expression of the symbiosis marker genes nodule inception and nodulation pectate lyase and reduced the numbers of infection threads and nodules on M. truncatula A17 roots, indicating that Pst DC3000 inhibits the establishment of symbiosis in M. truncatula. In addition, defense-related genes, such as MAPK3/6, RbohC, and WRKY33, exhibited a transient increase in their expression in the early stage of symbiosis with Sm2011, but the expression dropped down to normal levels at later symbiotic stages. Our results suggest that plant innate immunity plays an antagonistic role in symbiosis by directly reducing the numbers of infection threads and nodules.
Collapse
Affiliation(s)
- Tao Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China.,The Provincial Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Liujian Duan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Bo Zhou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Haixiang Yu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Hui Zhu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Yangrong Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| | - Zhongming Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China
| |
Collapse
|
75
|
Nguyen TT, Lee HH, Park J, Park I, Seo YS. Computational Identification and Comparative Analysis of Secreted and Transmembrane Proteins in Six Burkholderia Species. THE PLANT PATHOLOGY JOURNAL 2017; 33:148-162. [PMID: 28381962 PMCID: PMC5378436 DOI: 10.5423/ppj.oa.11.2016.0252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/02/2017] [Accepted: 01/05/2017] [Indexed: 05/14/2023]
Abstract
As a step towards discovering novel pathogenesis-related proteins, we performed a genome scale computational identification and characterization of secreted and transmembrane (TM) proteins, which are mainly responsible for bacteria-host interactions and interactions with other bacteria, in the genomes of six representative Burkholderia species. The species comprised plant pathogens (B. glumae BGR1, B. gladioli BSR3), human pathogens (B. pseudomallei K96243, B. cepacia LO6), and plant-growth promoting endophytes (Burkholderia sp. KJ006, B. phytofirmans PsJN). The proportions of putative classically secreted proteins (CSPs) and TM proteins among the species were relatively high, up to approximately 20%. Lower proportions of putative type 3 non-classically secreted proteins (T3NCSPs) (~10%) and unclassified non-classically secreted proteins (NCSPs) (~5%) were observed. The numbers of TM proteins among the three clusters (plant pathogens, human pathogens, and endophytes) were different, while the distribution of these proteins according to the number of TM domains was conserved in which TM proteins possessing 1, 2, 4, or 12 TM domains were the dominant groups in all species. In addition, we observed conservation in the protein size distribution of the secreted protein groups among the species. There were species-specific differences in the functional characteristics of these proteins in the various groups of CSPs, T3NCSPs, and unclassified NCSPs. Furthermore, we assigned the complete sets of the conserved and unique NCSP candidates of the collected Burkholderia species using sequence similarity searching. This study could provide new insights into the relationship among plant-pathogenic, human-pathogenic, and endophytic bacteria.
Collapse
Affiliation(s)
- Thao Thi Nguyen
- Department of Microbiology, Pusan National University, Busan 46241,
Korea
| | - Hyun-Hee Lee
- Department of Microbiology, Pusan National University, Busan 46241,
Korea
| | - Jungwook Park
- Department of Microbiology, Pusan National University, Busan 46241,
Korea
| | - Inmyoung Park
- Department of Microbiology, Pusan National University, Busan 46241,
Korea
- Department of Asian Food and Culinary Arts, Youngsan University, Busan 48015,
Korea
| | - Young-Su Seo
- Department of Microbiology, Pusan National University, Busan 46241,
Korea
| |
Collapse
|
76
|
Cui H, Gobbato E, Kracher B, Qiu J, Bautor J, Parker JE. A core function of EDS1 with PAD4 is to protect the salicylic acid defense sector in Arabidopsis immunity. THE NEW PHYTOLOGIST 2017; 213:1802-1817. [PMID: 27861989 DOI: 10.1111/nph.14302] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/23/2016] [Indexed: 05/19/2023]
Abstract
Plant defenses induced by salicylic acid (SA) are vital for resistance against biotrophic pathogens. In basal and receptor-triggered immunity, SA accumulation is promoted by Enhanced Disease Susceptibility1 with its co-regulator Phytoalexin Deficient4 (EDS1/PAD4). Current models position EDS1/PAD4 upstream of SA but their functional relationship remains unclear. In a genetic and transcriptomic analysis of Arabidopsis autoimmunity caused by constitutive or conditional EDS1/PAD4 overexpression, intrinsic EDS1/PAD4 signaling properties and their relation to SA were uncovered. A core EDS1/PAD4 pathway works in parallel with SA in basal and effector-triggered bacterial immunity. It protects against disabled SA-regulated gene expression and pathogen resistance, and is distinct from a known SA-compensatory route involving MAPK signaling. Results help to explain previously identified EDS1/PAD4 regulated SA-dependent and SA-independent gene expression sectors. Plants have evolved an alternative route for preserving SA-regulated defenses against pathogen or genetic perturbations. In a proposed signaling framework, EDS1 with PAD4, besides promoting SA biosynthesis, maintains important SA-related resistance programs, thereby increasing robustness of the innate immune system.
Collapse
Affiliation(s)
- Haitao Cui
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Enrico Gobbato
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Barbara Kracher
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jingde Qiu
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jaqueline Bautor
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jane E Parker
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| |
Collapse
|
77
|
Jwa NS, Hwang BK. Convergent Evolution of Pathogen Effectors toward Reactive Oxygen Species Signaling Networks in Plants. FRONTIERS IN PLANT SCIENCE 2017; 8:1687. [PMID: 29033963 PMCID: PMC5627460 DOI: 10.3389/fpls.2017.01687] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 09/13/2017] [Indexed: 05/03/2023]
Abstract
Microbial pathogens have evolved protein effectors to promote virulence and cause disease in host plants. Pathogen effectors delivered into plant cells suppress plant immune responses and modulate host metabolism to support the infection processes of pathogens. Reactive oxygen species (ROS) act as cellular signaling molecules to trigger plant immune responses, such as pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity. In this review, we discuss recent insights into the molecular functions of pathogen effectors that target multiple steps in the ROS signaling pathway in plants. The perception of PAMPs by pattern recognition receptors leads to the rapid and strong production of ROS through activation of NADPH oxidase Respiratory Burst Oxidase Homologs (RBOHs) as well as peroxidases. Specific pathogen effectors directly or indirectly interact with plant nucleotide-binding leucine-rich repeat receptors to induce ROS production and the hypersensitive response in plant cells. By contrast, virulent pathogens possess effectors capable of suppressing plant ROS bursts in different ways during infection. PAMP-triggered ROS bursts are suppressed by pathogen effectors that target mitogen-activated protein kinase cascades. Moreover, pathogen effectors target vesicle trafficking or metabolic priming, leading to the suppression of ROS production. Secreted pathogen effectors block the metabolic coenzyme NADP-malic enzyme, inhibiting the transfer of electrons to the NADPH oxidases (RBOHs) responsible for ROS generation. Collectively, pathogen effectors may have evolved to converge on a common host protein network to suppress the common plant immune system, including the ROS burst and cell death response in plants.
Collapse
Affiliation(s)
- Nam-Soo Jwa
- Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul, South Korea
- *Correspondence: Nam-Soo Jwa,
| | - Byung Kook Hwang
- Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul, South Korea
| |
Collapse
|
78
|
Ramachandran SR, Yin C, Kud J, Tanaka K, Mahoney AK, Xiao F, Hulbert SH. Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses. PHYTOPATHOLOGY 2017; 107:75-83. [PMID: 27503371 DOI: 10.1094/phyto-02-16-0083-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (<300 amino acids), secreted proteins, with no predicted functions were selected for the HR suppression assay using Nicotiana benthamiana, in which each of the proteins were transiently expressed and evaluated for their ability to suppress HR caused by four cytotoxic effector-R gene combinations (Cp/Rx, ATR13/RPP13, Rpt2/RPS-2, and GPA/RBP-1) and one mutated R gene-Pto(Y207D). Nine out of twenty proteins, designated Shr1 to Shr9 (suppressors of hypersensitive response), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, effector Shr7 also suppressed PAMP-triggered immune response triggered by flg22. Finally, delivery of Shr7 through Pseudomonas fluorescens EtHAn suppressed nonspecific HR induced by Pseudomonas syringae DC3000 in wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.
Collapse
Affiliation(s)
- Sowmya R Ramachandran
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Chuntao Yin
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Joanna Kud
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Kiwamu Tanaka
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Aaron K Mahoney
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Fangming Xiao
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Scot H Hulbert
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| |
Collapse
|
79
|
Drehkopf S, Hausner J, Jordan M, Scheibner F, Bonas U, Büttner D. A TAL-Based Reporter Assay for Monitoring Type III-Dependent Protein Translocation in Xanthomonas. Methods Mol Biol 2017; 1531:121-139. [PMID: 27837487 DOI: 10.1007/978-1-4939-6649-3_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gram-negative plant- and animal-pathogenic bacteria use type III secretion (T3S) systems to translocate effector proteins into eukaryotic host cells. Type III-dependent delivery of effector proteins depends on a secretion and translocation signal, which is often located in the N-terminal protein region and is not conserved on the amino acid level. Translocation signals in effector proteins have been experimentally confirmed by employing reporter proteins, which are specifically activated inside eukaryotic cells. Here, we describe a method to monitor effector protein translocation using a deletion derivative of the transcription activator-like (TAL) effector protein AvrBs3 as reporter. AvrBs3 is a type III effector of the tomato and pepper pathogen X. campestris pv. vesicatoria and is imported into the plant cell nucleus where it binds to specific promoter elements of target genes and activates their transcription. The N-terminal deletion derivative AvrBs3∆2 lacks a functional T3S and translocation signal but contains the effector domain and induces plant gene expression when fused to a functional translocation signal. In resistant pepper plants, AvrBs3 and translocated AvrBs3∆2 fusion proteins induce the expression of the Bs3-resistance gene, which triggers a strong, macroscopically visible defense response. The protocol for translocation assays with AvrBs3∆2 fusion proteins includes (1) the generation of expression constructs by Golden Gate cloning, (2) the transfer of expression constructs into bacterial recipient strains, (3) in vitro secretion assays with reporter fusion proteins and (4) infection of AvrBs3-responsive pepper plants.
Collapse
Affiliation(s)
- Sabine Drehkopf
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Jens Hausner
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Michael Jordan
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Felix Scheibner
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Ulla Bonas
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Daniela Büttner
- Department of Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany.
| |
Collapse
|
80
|
Ji Z, Ji C, Liu B, Zou L, Chen G, Yang B. Interfering TAL effectors of Xanthomonas oryzae neutralize R-gene-mediated plant disease resistance. Nat Commun 2016; 7:13435. [PMID: 27811915 PMCID: PMC5097170 DOI: 10.1038/ncomms13435] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/04/2016] [Indexed: 12/21/2022] Open
Abstract
Plant pathogenic bacteria of the genus Xanthomonas possess transcription activator-like effectors (TALEs) that activate transcription of disease susceptibility genes in the host, inducing a state of disease. Here we report that some isolates of the rice pathogen Xanthomonas oryzae use truncated versions of TALEs (which we term interfering TALEs, or iTALEs) to overcome disease resistance. In comparison with typical TALEs, iTALEs lack a transcription activation domain but retain nuclear localization motifs and are expressed from genes that were previously considered pseudogenes. We show that the rice gene Xa1, encoding a nucleotide-binding leucine-rich repeat protein, confers resistance against X. oryzae isolates by recognizing multiple TALEs. However, the iTALEs present in many isolates interfere with the otherwise broad-spectrum resistance conferred by Xa1. Our findings illustrate how bacterial effectors that trigger disease resistance in the host can evolve to interfere with the resistance process and, thus, promote disease. The rice pathogen Xanthomonas oryzae produces TAL effectors (TALEs) that promote virulence. Here, the authors identify truncated TALEs that interfere with the function of a rice gene, Xa1, which confers resistance to all tested full-length TALEs.
Collapse
Affiliation(s)
- Zhiyuan Ji
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai 200240, China.,Department of Genetics, Development and Cell Biology, Iowa State University, 1035C Roy J. Carver Co-Lab, Ames, Iowa 50011, USA
| | - Chonghui Ji
- Department of Genetics, Development and Cell Biology, Iowa State University, 1035C Roy J. Carver Co-Lab, Ames, Iowa 50011, USA
| | - Bo Liu
- Department of Genetics, Development and Cell Biology, Iowa State University, 1035C Roy J. Carver Co-Lab, Ames, Iowa 50011, USA
| | - Lifang Zou
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Gongyou Chen
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Yang
- Department of Genetics, Development and Cell Biology, Iowa State University, 1035C Roy J. Carver Co-Lab, Ames, Iowa 50011, USA
| |
Collapse
|
81
|
Palma-Martínez I, Guerrero-Mandujano A, Ruiz-Ruiz MJ, Hernández-Cortez C, Molina-López J, Bocanegra-García V, Castro-Escarpulli G. Active Shiga-Like Toxin Produced by Some Aeromonas spp., Isolated in Mexico City. Front Microbiol 2016; 7:1552. [PMID: 27757103 PMCID: PMC5048074 DOI: 10.3389/fmicb.2016.01552] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/16/2016] [Indexed: 12/29/2022] Open
Abstract
RNA silencing is a conserved mechanism that utilizes small RNAs (sRNAs) to direct the regulation of gene expression at the transcriptional or post-transcriptional level. Plants utilizing RNA silencing machinery to defend pathogen infection was first identified in plant–virus interaction and later was observed in distinct plant–pathogen interactions. RNA silencing is not only responsible for suppressing RNA accumulation and movement of virus and viroid, but also facilitates plant immune responses against bacterial, oomycete, and fungal infection. Interestingly, even the same plant sRNA can perform different roles when encounters with different pathogens. On the other side, pathogens counteract by generating sRNAs that directly regulate pathogen gene expression to increase virulence or target host genes to facilitate pathogen infection. Here, we summarize the current knowledge of the characterization and biogenesis of host- and pathogen-derived sRNAs, as well as the different RNA silencing machineries that plants utilize to defend against different pathogens. The functions of these sRNAs in defense and counter-defense and their mechanisms for regulation during different plant–pathogen interactions are also discussed.
Collapse
Affiliation(s)
- Ingrid Palma-Martínez
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
| | - Andrea Guerrero-Mandujano
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
| | - Manuel J Ruiz-Ruiz
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico; Laboratorio Central de Análisis Clínicos Unidad Médica de Alta Especialidad Hospital de Pediatría "Silvestre Frenk Freund," Centro Médico Nacional Siglo XXIMexico City, Mexico
| | - Cecilia Hernández-Cortez
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico; Laboratorio de Bioquímica Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico
| | - José Molina-López
- Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico
| | | | - Graciela Castro-Escarpulli
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
| |
Collapse
|
82
|
Quibod IL, Perez-Quintero A, Booher NJ, Dossa GS, Grande G, Szurek B, Vera Cruz C, Bogdanove AJ, Oliva R. Effector Diversification Contributes to Xanthomonas oryzae pv. oryzae Phenotypic Adaptation in a Semi-Isolated Environment. Sci Rep 2016; 6:34137. [PMID: 27667260 PMCID: PMC5035989 DOI: 10.1038/srep34137] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/07/2016] [Indexed: 01/01/2023] Open
Abstract
Understanding the processes that shaped contemporary pathogen populations in agricultural landscapes is quite important to define appropriate management strategies and to support crop improvement efforts. Here, we took advantage of an historical record to examine the adaptation pathway of the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo) in a semi-isolated environment represented in the Philippine archipelago. By comparing genomes of key Xoo groups we showed that modern populations derived from three Asian lineages. We also showed that diversification of virulence factors occurred within each lineage, most likely driven by host adaptation, and it was essential to shape contemporary pathogen races. This finding is particularly important because it expands our understanding of pathogen adaptation to modern agriculture.
Collapse
Affiliation(s)
- Ian Lorenzo Quibod
- Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines
| | - Alvaro Perez-Quintero
- Résistance des Plantes aux Bioagresseurs, Institut de Recherche pour le Développement, Montpellier, France
| | - Nicholas J Booher
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Gerbert S Dossa
- Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines
| | - Genelou Grande
- Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines
| | - Boris Szurek
- Résistance des Plantes aux Bioagresseurs, Institut de Recherche pour le Développement, Montpellier, France
| | - Casiana Vera Cruz
- Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines
| | - Adam J Bogdanove
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Ricardo Oliva
- Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Philippines
| |
Collapse
|
83
|
Zhou JM, Yang WC. Receptor-like kinases take center stage in plant biology. SCIENCE CHINA-LIFE SCIENCES 2016; 59:863-6. [DOI: 10.1007/s11427-016-5112-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
84
|
Wang S, Sun J, Fan F, Tan Z, Zou Y, Lu D. A Xanthomonas oryzae pv. oryzae effector, XopR, associates with receptor-like cytoplasmic kinases and suppresses PAMP-triggered stomatal closure. SCIENCE CHINA-LIFE SCIENCES 2016; 59:897-905. [PMID: 27520828 DOI: 10.1007/s11427-016-5106-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 06/20/2016] [Indexed: 01/20/2023]
Abstract
Receptor-like kinases (RLKs) play important roles in plant immunity signaling; thus, many are hijacked by pathogen effectors to promote successful pathogenesis. Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice leaf blight disease. The strain PXO99A has 18 non-TAL (transcription activation-like) effectors; however, their mechanisms of action and host target proteins remain largely unknown. Although the effector XopR from the Xoo strain MAFF311018 was shown to suppress PAMP-triggered immune responses in Arabidopsis, its target has not yet been identified. Here, we show that PXO99A XopR interacts with BIK1 at the plasma membrane. BIK1 is a receptor-like cytoplasmic kinase (RLCK) belonging to the RLK family of proteins and mediates PAMP-triggered stomatal immunity. In turn, BIK1 phosphorylates XopR. Furthermore, XopR suppresses PAMP-triggered stomatal closure in transgenic Arabidopsis expressing XopR. In addition, XopR is able to associate with RLCKs other than BIK1. These results suggest that XopR likely suppresses plant immunity by targeting BIK1 and other RLCKs.
Collapse
Affiliation(s)
- Shuangfeng Wang
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianhang Sun
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fenggui Fan
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhaoyun Tan
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
| | - Yanmin Zou
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China
| | - Dongping Lu
- State Key Laboratory of Plant Genomics, Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, 050021, China.
| |
Collapse
|
85
|
Popov G, Fraiture M, Brunner F, Sessa G. Multiple Xanthomonas euvesicatoria Type III Effectors Inhibit flg22-Triggered Immunity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:651-60. [PMID: 27529660 DOI: 10.1094/mpmi-07-16-0137-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Xanthomonas euvesicatoria is the causal agent of bacterial spot disease in pepper and tomato. X. euvesicatoria bacteria interfere with plant cellular processes by injecting effector proteins into host cells through the type III secretion (T3S) system. About 35 T3S effectors have been identified in X. euvesicatoria 85-10, and a few of them were implicated in suppression of pattern-triggered immunity (PTI). We used an Arabidopsis thaliana pathogen-free protoplast-based assay to identify X. euvesicatoria 85-10 effectors that interfere with PTI signaling induced by the bacterial peptide flg22. Of 33 tested effectors, 17 inhibited activation of a PTI-inducible promoter. Among them, nine effectors also interfered with activation of an abscisic acid-inducible promoter. However, effectors that inhibited flg22-induced signaling did not affect phosphorylation of mitogen-activated protein (MAP) kinases acting downstream of flg22 perception. Further investigation of selected effectors revealed that XopAJ, XopE2, and XopF2 inhibited activation of a PTI-inducible promoter by the bacterial peptide elf18 in Arabidopsis protoplasts and by flg22 in tomato protoplasts. The effectors XopF2, XopE2, XopAP, XopAE, XopH, and XopAJ inhibited flg22-induced callose deposition in planta and enhanced disease symptoms caused by attenuated Pseudomonas syringae bacteria. Finally, selected effectors were found to localize to various plant subcellular compartments. These results indicate that X. euvesicatoria bacteria utilize multiple T3S effectors to suppress flg22-induced signaling acting downstream or in parallel to MAP kinase cascades and suggest they act through different molecular mechanisms.
Collapse
Affiliation(s)
- Georgy Popov
- 1 Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, 69978 Tel-Aviv, Israel; and
| | - Malou Fraiture
- 2 Department of Biochemistry, Centre for Plant Molecular Biology, Eberhard Karls University, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Frederic Brunner
- 2 Department of Biochemistry, Centre for Plant Molecular Biology, Eberhard Karls University, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Guido Sessa
- 1 Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, 69978 Tel-Aviv, Israel; and
| |
Collapse
|
86
|
Ma KW, Ma W. Phytohormone pathways as targets of pathogens to facilitate infection. PLANT MOLECULAR BIOLOGY 2016; 91:713-25. [PMID: 26879412 PMCID: PMC4932134 DOI: 10.1007/s11103-016-0452-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 02/07/2016] [Indexed: 05/18/2023]
Abstract
Plants are constantly threatened by potential pathogens. In order to optimize the output of defense against pathogens with distinct lifestyles, plants depend on hormonal networks to fine-tune specific responses and regulate growth-defense tradeoffs. To counteract, pathogens have evolved various strategies to disturb hormonal homeostasis and facilitate infection. Many pathogens synthesize plant hormones; more importantly, toxins and effectors are produced to manipulate hormonal crosstalk. Accumulating evidence has shown that pathogens exert extensive effects on plant hormone pathways not only to defeat immunity, but also modify habitat structure, optimize nutrient acquisition, and facilitate pathogen dissemination. In this review, we summarize mechanisms by which a wide array of pathogens gain benefits from manipulating plant hormone pathways.
Collapse
Affiliation(s)
- Ka-Wai Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA, 92521, USA.
- Center for Plant Cell Biology, University of California, Riverside, CA, 92521, USA.
| | - Wenbo Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA, 92521, USA.
- Center for Plant Cell Biology, University of California, Riverside, CA, 92521, USA.
| |
Collapse
|
87
|
Schreiber KJ, Baudin M, Hassan JA, Lewis JD. Die another day: Molecular mechanisms of effector-triggered immunity elicited by type III secreted effector proteins. Semin Cell Dev Biol 2016; 56:124-133. [DOI: 10.1016/j.semcdb.2016.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/02/2016] [Indexed: 11/27/2022]
|
88
|
|
89
|
The Xanthomonas campestris pv. vesicatoria Type-3 Effector XopB Inhibits Plant Defence Responses by Interfering with ROS Production. PLoS One 2016; 11:e0159107. [PMID: 27398933 PMCID: PMC4939948 DOI: 10.1371/journal.pone.0159107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/27/2016] [Indexed: 11/19/2022] Open
Abstract
The bacterial pathogen Xanthomonas campestris pv. vesicatoria 85-10 (Xcv) translocates about 30 type-3 effector proteins (T3Es) into pepper plants (Capsicum annuum) to suppress plant immune responses. Among them is XopB which interferes with PTI, ETI and sugar-mediated defence responses, but the underlying molecular mechanisms and direct targets are unknown so far. Here, we examined the XopB-mediated suppression of plant defence responses in more detail. Infection of susceptible pepper plants with Xcv lacking xopB resulted in delayed symptom development compared to Xcv wild type infection concomitant with an increased formation of salicylic acid (SA) and expression of pathogenesis-related (PR) genes. Expression of xopB in Arabidopsis thaliana promoted the growth of the virulent Pseudomonas syringae pv. tomato (Pst) DC3000 strain. This was paralleled by a decreased SA-pool and a lower induction of SA-dependent PR gene expression. The expression pattern of early flg22-responsive marker genes indicated that MAPK signalling was not altered in the presence of XopB. However, XopB inhibited the flg22-triggered burst of reactive oxygen species (ROS). Consequently, the transcript accumulation of AtOXI1, a ROS-dependent marker gene, was reduced in xopB-expressing Arabidopsis plants as well as callose deposition. The lower ROS production correlated with a low level of basal and flg22-triggered expression of apoplastic peroxidases and the NADPH oxidase RBOHD. Conversely, deletion of xopB in Xcv caused a higher production of ROS in leaves of susceptible pepper plants. Together our results demonstrate that XopB modulates ROS responses and might thereby compromise plant defence.
Collapse
|
90
|
Holtappels M, Noben JP, Valcke R. Virulence of Erwinia amylovora, a prevalent apple pathogen: Outer membrane proteins and type III secreted effectors increase fitness and compromise plant defenses. Proteomics 2016; 16:2377-90. [PMID: 27345300 DOI: 10.1002/pmic.201500513] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 01/30/2023]
Abstract
Until now, no data are available on the outer membrane (OM) proteome of Erwinia amylovora, a Gram-negative plant pathogen, causing fire blight in most of the members of the Rosaceae family. Since the OM forms the interface between the bacterial cell and its environment it is in direct contact with the host. Additionally, the type III secretion system, embedded in the OM, is a pathogenicity factor of E. amylovora. To assess the influence of the OM composition and the secretion behavior on virulence, a 2D-DIGE analysis and gene expression profiling were performed on a high and lower virulent strain, both in vitro and in planta. Proteome data showed an increase in flagellin for the lower virulent strain in vitro, whereas, in planta several interesting proteins were identified as being differently expressed between both the strains. Further, gene expression of nearly all type III secreted effectors was elevated for the higher virulent strain, both in vitro and in planta. As a first, we report that several characteristics of virulence can be assigned to the OM proteome. Moreover, we demonstrate that secreted proteins prove to be the important factors determining differences in virulence between the strains, otherwise regarded as homogeneous on a genome level.
Collapse
Affiliation(s)
- Michelle Holtappels
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium
| | - Jean-Paul Noben
- School of Life Sciences, Biomedical Research Institute, Hasselt University and Transnational University Limburg, Hasselt, Belgium
| | - Roland Valcke
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium.
| |
Collapse
|
91
|
Reimer-Michalski EM, Conrath U. Innate immune memory in plants. Semin Immunol 2016; 28:319-27. [PMID: 27264335 DOI: 10.1016/j.smim.2016.05.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/12/2016] [Accepted: 05/17/2016] [Indexed: 12/26/2022]
Abstract
The plant innate immune system comprises local and systemic immune responses. Systemic plant immunity develops after foliar infection by microbial pathogens, upon root colonization by certain microbes, or in response to physical injury. The systemic plant immune response to localized foliar infection is associated with elevated levels of pattern-recognition receptors, accumulation of dormant signaling enzymes, and alterations in chromatin state. Together, these systemic responses provide a memory to the initial infection by priming the remote leaves for enhanced defense and immunity to reinfection. The plant innate immune system thus builds immunological memory by utilizing mechanisms and components that are similar to those employed in the trained innate immune response of jawed vertebrates. Therefore, there seems to be conservation, or convergence, in the evolution of innate immune memory in plants and vertebrates.
Collapse
Affiliation(s)
| | - Uwe Conrath
- Department of Plant Physiology, RWTH Aachen University, Aachen 52056, Germany.
| |
Collapse
|
92
|
Wang YJ, Wei XY, Jing XQ, Chang YL, Hu CH, Wang X, Chen KM. The Fundamental Role of NOX Family Proteins in Plant Immunity and Their Regulation. Int J Mol Sci 2016; 17:ijms17060805. [PMID: 27240354 PMCID: PMC4926339 DOI: 10.3390/ijms17060805] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 05/10/2016] [Accepted: 05/11/2016] [Indexed: 01/01/2023] Open
Abstract
NADPH oxidases (NOXs), also known as respiratory burst oxidase homologs (RBOHs), are the major source of reactive oxygen species (ROS), and are involved in many important processes in plants such as regulation of acclimatory signaling and programmed cell death (PCD). Increasing evidence shows that NOXs play crucial roles in plant immunity and their functions in plant immune responses are not as separate individuals but with other signal molecules such as kinases, Rac/Rop small GTPases and hormones, mediating a series of signal transmissions. In a similar way, NOX-mediated signaling also participates in abiotic stress response of plants. We summarized here the complex role and regulation mechanism of NOXs in mediating plant immune response, and the viewpoint that abiotic stress response of plants may be a kind of special plant immunity is also proposed.
Collapse
Affiliation(s)
- Ya-Jing Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Xiao-Yong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Xiu-Qing Jing
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Yan-Li Chang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Chun-Hong Hu
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Xiang Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| | - Kun-Ming Chen
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| |
Collapse
|
93
|
Huang J, Yang M, Zhang X. The function of small RNAs in plant biotic stress response. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:312-27. [PMID: 26748943 DOI: 10.1111/jipb.12463] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/07/2016] [Indexed: 05/18/2023]
Abstract
Small RNAs (sRNAs) play essential roles in plants upon biotic stress. Plants utilize RNA silencing machinery to facilitate pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to defend against pathogen attack or to facilitate defense against insect herbivores. Pathogens, on the other hand, are also able to generate effectors and sRNAs to counter the host immune response. The arms race between plants and pathogens/insect herbivores has triggered the evolution of sRNAs, RNA silencing machinery and pathogen effectors. A great number of studies have been performed to investigate the roles of sRNAs in plant defense, bringing in the opportunity to utilize sRNAs in plant protection. Transgenic plants with pathogen-derived resistance ability or transgenerational defense have been generated, which show promising potential as solutions for pathogen/insect herbivore problems in the field. Here we summarize the recent progress on the function of sRNAs in response to biotic stress, mainly in plant-pathogen/insect herbivore interaction, and the application of sRNAs in disease and insect herbivore control.
Collapse
Affiliation(s)
- Juan Huang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Meiling Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xiaoming Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
94
|
Ge YY, Xiang QW, Wagner C, Zhang D, Xie ZP, Staehelin C. The type 3 effector NopL of Sinorhizobium sp. strain NGR234 is a mitogen-activated protein kinase substrate. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2483-94. [PMID: 26931172 DOI: 10.1093/jxb/erw065] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pathogenic bacteria utilize type 3 secretion systems to inject type 3 effectors (T3Es) into host cells, thereby subverting host defense reactions. Similarly, T3Es of symbiotic nitrogen-fixing rhizobia can affect nodule formation on roots of legumes. Previous work showed that NopL (nodulation outer protein L) of Sinorhizobium(Ensifer) sp. strain NGR234 is multiply phosphorylated in eukaryotic cells and that this T3E suppresses responses mediated by mitogen-activated protein (MAP) kinase signaling in yeast (mating pheromone signaling) and plant cells (expression of pathogenesis-related defense proteins). Here, we show that NopL is a MAP kinase substrate. Microscopic observations of fluorescent fusion proteins and bimolecular fluorescence complementation analysis in onion cells indicated that NopL is targeted to the nucleus and forms a complex with SIPK (salicylic acid-induced protein kinase), a MAP kinase of tobacco. In vitro experiments demonstrated that NopL is phosphorylatyed by SIPK. At least nine distinct spots were observed after two-dimensional gel electrophoresis, indicating that NopL can be hyperphosphorylated by MAP kinases. Senescence symptoms in nodules of beans (Phaseolus vulgaris cv. Tendergreen) were analyzed to determine the symbiotic effector activity of different NopL variants with serine to alanine substitutions at identified and predicted phosphorylation sites (serine-proline motif). NopL variants with six or eight serine to alanine substitutions were partially active, whereas NopL forms with 10 or 12 substituted serine residues were inactive. In conclusion, our findings provide evidence that NopL interacts with MAP kinases and reveals the importance of serine-proline motifs for effector activity during symbiosis.
Collapse
Affiliation(s)
- Ying-Ying Ge
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qi-Wang Xiang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Christian Wagner
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Di Zhang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Shenzhen Research and Development Center of State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Baoan, Shenzhen, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Shenzhen Research and Development Center of State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Baoan, Shenzhen, China
| |
Collapse
|
95
|
A novel method of transcriptome interpretation reveals a quantitative suppressive effect on tomato immune signaling by two domains in a single pathogen effector protein. BMC Genomics 2016; 17:229. [PMID: 26976140 PMCID: PMC4790048 DOI: 10.1186/s12864-016-2534-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 02/25/2016] [Indexed: 11/21/2022] Open
Abstract
Background Effector proteins are translocated into host cells by plant-pathogens to undermine pattern-triggered immunity (PTI), the plant response to microbe-associated molecular patterns that interferes with the infection process. Individual effectors are found in variable repertoires where some constituents target the same pathways. The effector protein AvrPto from Pseudomonas syringae has a core domain (CD) and C-terminal domain (CTD) that each promotes bacterial growth and virulence in tomato. The individual contributions of each domain and whether they act redundantly is unknown. Results We use RNA-Seq to elucidate the contribution of the CD and CTD to the suppression of PTI in tomato leaves 6 h after inoculation. Unexpectedly, each domain alters transcript levels of essentially the same genes but to a different degree. This difference, when quantified, reveals that although targeting the same host genes, the two domains act synergistically. AvrPto has a relatively greater effect on genes whose expression is suppressed during PTI, and the effect on these genes appears to be diminished by saturation. Conclusions RNA-Seq profiles can be used to observe relative contributions of effector subdomains to PTI suppression. Our analysis shows the CD and CTD multiplicatively affect the same gene transcript levels with a greater relative impact on genes whose expression is suppressed during PTI. The higher degree of up-regulation versus down-regulation during PTI is plausibly an evolutionary adaptation against effectors that target immune signaling. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2534-4) contains supplementary material, which is available to authorized users.
Collapse
|
96
|
Boyle PC, Schwizer S, Hind SR, Kraus CM, De la Torre Diaz S, He B, Martin GB. Detecting N-myristoylation and S-acylation of host and pathogen proteins in plants using click chemistry. PLANT METHODS 2016; 12:38. [PMID: 27493678 PMCID: PMC4972946 DOI: 10.1186/s13007-016-0138-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 07/20/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND The plant plasma membrane is a key battleground in the war between plants and their pathogens. Plants detect the presence of pathogens at the plasma membrane using sensor proteins, many of which are targeted to this lipophilic locale by way of fatty acid modifications. Pathogens secrete effector proteins into the plant cell to suppress the plant's defense mechanisms. These effectors are able to access and interfere with the surveillance machinery at the plant plasma membrane by hijacking the host's fatty acylation apparatus. Despite the important involvement of protein fatty acylation in both plant immunity and pathogen virulence mechanisms, relatively little is known about the role of this modification during plant-pathogen interactions. This dearth in our understanding is due largely to the lack of methods to monitor protein fatty acid modifications in the plant cell. RESULTS We describe a rapid method to detect two major forms of fatty acylation, N-myristoylation and S-acylation, of candidate proteins using alkyne fatty acid analogs coupled with click chemistry. We applied our approach to confirm and decisively demonstrate that the archetypal pattern recognition receptor FLS2, the well-characterized pathogen effector AvrPto, and one of the best-studied intracellular resistance proteins, Pto, all undergo plant-mediated fatty acylation. In addition to providing a means to readily determine fatty acylation, particularly myristoylation, of candidate proteins, this method is amenable to a variety of expression systems. We demonstrate this using both Arabidopsis protoplasts and stable transgenic Arabidopsis plants and we leverage Agrobacterium-mediated transient expression in Nicotiana benthamiana leaves as a means for high-throughput evaluation of candidate proteins. CONCLUSIONS Protein fatty acylation is a targeting tactic employed by both plants and their pathogens. The metabolic labeling approach leveraging alkyne fatty acid analogs and click chemistry described here has the potential to provide mechanistic details of the molecular tactics used at the host plasma membrane in the battle between plants and pathogens.
Collapse
Affiliation(s)
- Patrick C. Boyle
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Monsanto Company, St. Louis, MO 63141 USA
| | - Simon Schwizer
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
| | - Sarah R. Hind
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
| | - Christine M. Kraus
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
| | | | - Bin He
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 USA
- College of Pharmacy, Guiyang Medical University, Guiyang, 550004 Guizhou China
| | - Gregory B. Martin
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
| |
Collapse
|
97
|
Ma KW, Jiang S, Hawara E, Lee D, Pan S, Coaker G, Song J, Ma W. Two serine residues in Pseudomonas syringae effector HopZ1a are required for acetyltransferase activity and association with the host co-factor. THE NEW PHYTOLOGIST 2015; 208:1157-68. [PMID: 26103463 PMCID: PMC4768790 DOI: 10.1111/nph.13528] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 05/21/2015] [Indexed: 05/21/2023]
Abstract
Gram-negative bacteria inject type III secreted effectors (T3SEs) into host cells to manipulate the immune response. The YopJ family effector HopZ1a produced by the plant pathogen Pseudomonas syringae possesses acetyltransferase activity and acetylates plant proteins to facilitate infection. Using mass spectrometry, we identified a threonine residue, T346, as the main autoacetylation site of HopZ1a. Two neighboring serine residues, S349 and S351, are required for the acetyltransferase activity of HopZ1a in vitro and are indispensable for the virulence function of HopZ1a in Arabidopsis thaliana. Using proton nuclear magnetic resonance (NMR), we observed a conformational change of HopZ1a in the presence of inositol hexakisphosphate (IP6), which acts as a eukaryotic co-factor and significantly enhances the acetyltransferase activity of several YopJ family effectors. S349 and S351 are required for IP6-binding-mediated conformational change of HopZ1a. S349 and S351 are located in a conserved region in the C-terminal domain of YopJ family effectors. Mutations of the corresponding serine(s) in two other effectors, HopZ3 of P. syringae and PopP2 of Ralstonia solanacerum, also abolished their acetyltransferase activity. These results suggest that, in addition to the highly conserved catalytic residues, YopJ family effectors also require conserved serine(s) in the C-terminal domain for their enzymatic activity.
Collapse
Affiliation(s)
- Ka-Wai Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
| | - Shushu Jiang
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
| | - Eva Hawara
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - DongHyuk Lee
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Songqin Pan
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Jikui Song
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Wenbo Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
| |
Collapse
|
98
|
Pensec F, Lebeau A, Daunay MC, Chiroleu F, Guidot A, Wicker E. Towards the Identification of Type III Effectors Associated with Ralstonia solanacearum Virulence on Tomato and Eggplant. PHYTOPATHOLOGY 2015; 105:1529-44. [PMID: 26368514 DOI: 10.1094/phyto-06-15-0140-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For the development of pathogen-informed breeding strategies, identifying the microbial genes involved in interactions with the plant is a critical step. To identify type III effector (T3E) repertoires associated with virulence of the bacterial wilt pathogen Ralstonia solanacearum on Solanaceous crops, we used an original association genetics approach combining DNA microarray data and pathogenicity data on resistant eggplant, pepper, and tomato accessions. From this first screen, 25 T3Es were further full-length polymerase chain reaction-amplified within a 35-strain field collection, to assess their distribution and allelic diversity. Six T3E repertoire groups were identified, within which 11 representative strains were chosen to challenge the bacterial wilt-resistant egg plants 'Dingras multiple Purple' and 'AG91-25', and tomato Hawaii 7996. The virulence or avirulence phenotypes could not be explained by specific T3E repertoires, but rather by individual T3E genes. We identified seven highly avirulence-associated genes, among which ripP2, primarily referenced as conferring avirulence to Arabidopsis thaliana. Interestingly, no T3E was associated with avirulence to both egg-plants. Highly virulence-associated genes were also identified: ripA5_2, ripU, and ripV2. This study should be regarded as a first step toward investigating both avirulence and virulence function of the highlighted genes, but also their evolutionary dynamics in natural R. solanacearum populations.
Collapse
Affiliation(s)
- Flora Pensec
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| | - Aurore Lebeau
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| | - M C Daunay
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| | - Frédéric Chiroleu
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| | - Alice Guidot
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| | - Emmanuel Wicker
- First, second, fourth, and sixth authors: CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, France; third author: INRA, Centre d'Avignon, Unité de Génétique et Amélioration des Fruits et Légumes, UR1052, Montfavet, France; and fifth author: INRA, UMR 441 Laboratoire des Interactions Plantes-Microorganismes (LIPM), Castanet-Tolosan, France. Current address of first author: Institut National de la Recherche Agronomique, UMR A 1131 Santé de la Vigne et Qualité du Vin (SVQV), Colmar, France. Université de Strasbourg, Strasbourg, France
| |
Collapse
|
99
|
Abstract
Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial Nops (nodulation outer proteins) play a crucial symbiotic role in many strain-host combinations. Nops are defined as proteins secreted via a rhizobial T3SS (type III secretion system). Functional T3SSs have been characterized in many rhizobial strains. Nops have been identified using various genetic, biochemical, proteomic, genomic and experimental approaches. Certain Nops represent extracellular components of the T3SS, which are visible in electron micrographs as bacterial surface appendages called T3 (type III) pili. Other Nops are T3 effector proteins that can be translocated into plant cells. Rhizobial T3 effectors manipulate cellular processes in host cells to suppress plant defence responses against rhizobia and to promote symbiosis-related processes. Accordingly, mutant strains deficient in synthesis or secretion of T3 effectors show reduced symbiotic properties on certain host plants. On the other hand, direct or indirect recognition of T3 effectors by plant cells expressing specific R (resistance) proteins can result in effector triggered defence responses that negatively affect rhizobial infection. Hence Nops are double-edged swords that may promote establishment of symbiosis with one legume (symbiotic factors) and impair symbiotic processes when bacteria are inoculated on another legume species (asymbiotic factors). In the present review, we provide an overview of our current understanding of Nops. We summarize their symbiotic effects, their biochemical properties and their possible modes of action. Finally, we discuss future perspectives in the field of T3 effector research.
Collapse
|
100
|
Kørner CJ, Du X, Vollmer ME, Pajerowska-Mukhtar KM. Endoplasmic Reticulum Stress Signaling in Plant Immunity--At the Crossroad of Life and Death. Int J Mol Sci 2015; 16:26582-98. [PMID: 26556351 PMCID: PMC4661823 DOI: 10.3390/ijms161125964] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 01/01/2023] Open
Abstract
Rapid and complex immune responses are induced in plants upon pathogen recognition. One form of plant defense response is a programmed burst in transcription and translation of pathogenesis-related proteins, of which many rely on ER processing. Interestingly, several ER stress marker genes are up-regulated during early stages of immune responses, suggesting that enhanced ER capacity is needed for immunity. Eukaryotic cells respond to ER stress through conserved signaling networks initiated by specific ER stress sensors tethered to the ER membrane. Depending on the nature of ER stress the cell prioritizes either survival or initiates programmed cell death (PCD). At present two plant ER stress sensors, bZIP28 and IRE1, have been described. Both sensor proteins are involved in ER stress-induced signaling, but only IRE1 has been additionally linked to immunity. A second branch of immune responses relies on PCD. In mammals, ER stress sensors are involved in activation of PCD, but it is unclear if plant ER stress sensors play a role in PCD. Nevertheless, some ER resident proteins have been linked to pathogen-induced cell death in plants. In this review, we will discuss the current understanding of plant ER stress signaling and its cross-talk with immune signaling.
Collapse
Affiliation(s)
- Camilla J Kørner
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
| | - Xinran Du
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
| | - Marie E Vollmer
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294, USA.
| | | |
Collapse
|