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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]
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Choi K, Reinhard C, Serra H, Ziolkowski PA, Underwood CJ, Zhao X, Hardcastle TJ, Yelina NE, Griffin C, Jackson M, Mézard C, McVean G, Copenhaver GP, Henderson IR. Recombination Rate Heterogeneity within Arabidopsis Disease Resistance Genes. PLoS Genet 2016; 12:e1006179. [PMID: 27415776 PMCID: PMC4945094 DOI: 10.1371/journal.pgen.1006179] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 06/15/2016] [Indexed: 12/31/2022] Open
Abstract
Meiotic crossover frequency varies extensively along chromosomes and is typically concentrated in hotspots. As recombination increases genetic diversity, hotspots are predicted to occur at immunity genes, where variation may be beneficial. A major component of plant immunity is recognition of pathogen Avirulence (Avr) effectors by resistance (R) genes that encode NBS-LRR domain proteins. Therefore, we sought to test whether NBS-LRR genes would overlap with meiotic crossover hotspots using experimental genetics in Arabidopsis thaliana. NBS-LRR genes tend to physically cluster in plant genomes; for example, in Arabidopsis most are located in large clusters on the south arms of chromosomes 1 and 5. We experimentally mapped 1,439 crossovers within these clusters and observed NBS-LRR gene associated hotspots, which were also detected as historical hotspots via analysis of linkage disequilibrium. However, we also observed NBS-LRR gene coldspots, which in some cases correlate with structural heterozygosity. To study recombination at the fine-scale we used high-throughput sequencing to analyze ~1,000 crossovers within the RESISTANCE TO ALBUGO CANDIDA1 (RAC1) R gene hotspot. This revealed elevated intragenic crossovers, overlapping nucleosome-occupied exons that encode the TIR, NBS and LRR domains. The highest RAC1 recombination frequency was promoter-proximal and overlapped CTT-repeat DNA sequence motifs, which have previously been associated with plant crossover hotspots. Additionally, we show a significant influence of natural genetic variation on NBS-LRR cluster recombination rates, using crosses between Arabidopsis ecotypes. In conclusion, we show that a subset of NBS-LRR genes are strong hotspots, whereas others are coldspots. This reveals a complex recombination landscape in Arabidopsis NBS-LRR genes, which we propose results from varying coevolutionary pressures exerted by host-pathogen relationships, and is influenced by structural heterozygosity.
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Affiliation(s)
- Kyuha Choi
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Carsten Reinhard
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Heïdi Serra
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Piotr A. Ziolkowski
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
- Department of Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Charles J. Underwood
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Xiaohui Zhao
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Thomas J. Hardcastle
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Nataliya E. Yelina
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Catherine Griffin
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Matthew Jackson
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
| | - Christine Mézard
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, RD10, Versailles, France
| | - Gil McVean
- The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Gregory P. Copenhaver
- Department of Biology and the Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Ian R. Henderson
- Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge, United Kingdom
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Vasudevan K, Vera Cruz CM, Gruissem W, Bhullar NK. Geographically Distinct and Domain-Specific Sequence Variations in the Alleles of Rice Blast Resistance Gene Pib. FRONTIERS IN PLANT SCIENCE 2016; 7:915. [PMID: 27446145 PMCID: PMC4917536 DOI: 10.3389/fpls.2016.00915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 06/09/2016] [Indexed: 06/06/2023]
Abstract
Rice blast is caused by Magnaporthe oryzae, which is the most destructive fungal pathogen affecting rice growing regions worldwide. The rice blast resistance gene Pib confers broad-spectrum resistance against Southeast Asian M. oryzae races. We investigated the allelic diversity of Pib in rice germplasm originating from 12 major rice growing countries. Twenty-five new Pib alleles were identified that have unique single nucleotide polymorphisms (SNPs), insertions and/or deletions, in addition to the polymorphic nucleotides that are shared between the different alleles. These partially or completely shared polymorphic nucleotides indicate frequent sequence exchange events between the Pib alleles. In some of the new Pib alleles, nucleotide diversity is high in the LRR domain, whereas, in others it is distributed among the NB-ARC and LRR domains. Most of the polymorphic amino acids in LRR and NB-ARC2 domains are predicted as solvent-exposed. Several of the alleles and the unique SNPs are country specific, suggesting a diversifying selection of alleles in various geographical locations in response to the locally prevalent M. oryzae population. Together, the new Pib alleles are an important genetic resource for rice blast resistance breeding programs and provide new information on rice-M. oryzae interactions at the molecular level.
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Affiliation(s)
- Kumar Vasudevan
- Plant Biotechnology, Department of Biology ETH Zurich, Switzerland
| | | | - Wilhelm Gruissem
- Plant Biotechnology, Department of Biology ETH Zurich, Switzerland
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Sukarta OCA, Slootweg EJ, Goverse A. Structure-informed insights for NLR functioning in plant immunity. Semin Cell Dev Biol 2016; 56:134-149. [PMID: 27208725 DOI: 10.1016/j.semcdb.2016.05.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/11/2016] [Accepted: 05/17/2016] [Indexed: 01/07/2023]
Abstract
To respond to foreign invaders, plants have evolved a cell autonomous multilayered immune system consisting of extra- and intracellular immune receptors. Nucleotide binding and oligomerization domain (NOD)-like receptors (NLRs) mediate recognition of pathogen effectors inside the cell and trigger a host specific defense response, often involving controlled cell death. NLRs consist of a central nucleotide-binding domain, which is flanked by an N-terminal CC or TIR domain and a C-terminal leucine-rich repeat domain (LRR). These multidomain proteins function as a molecular switch and their activity is tightly controlled by intra and inter-molecular interactions. In contrast to metazoan NLRs, the structural basis underlying NLR functioning as a pathogen sensor and activator of immune responses in plants is largely unknown. However, the first crystal structures of a number of plant NLR domains were recently obtained. In addition, biochemical and structure-informed analyses revealed novel insights in the cooperation between NLR domains and the formation of pre- and post activation complexes, including the coordinated activity of NLR pairs as pathogen sensor and executor of immune responses. Moreover, the discovery of novel integrated domains underscores the structural diversity of NLRs and provides alternative models for how these immune receptors function in plants. In this review, we will highlight these recent advances to provide novel insights in the structural, biochemical and molecular aspects involved in plant NLR functioning.
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Affiliation(s)
- Octavina C A Sukarta
- Dept. of Plant Sciences, Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
| | - Erik J Slootweg
- Dept. of Plant Sciences, Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
| | - Aska Goverse
- Dept. of Plant Sciences, Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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Christie N, Tobias PA, Naidoo S, Külheim C. The Eucalyptus grandis NBS-LRR Gene Family: Physical Clustering and Expression Hotspots. FRONTIERS IN PLANT SCIENCE 2016; 6:1238. [PMID: 26793216 PMCID: PMC4709456 DOI: 10.3389/fpls.2015.01238] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 12/20/2015] [Indexed: 05/03/2023]
Abstract
Eucalyptus grandis is a commercially important hardwood species and is known to be susceptible to a number of pests and pathogens. Determining mechanisms of defense is therefore a research priority. The published genome for E. grandis has aided the identification of one important class of resistance (R) genes that incorporate nucleotide binding sites and leucine-rich repeat domains (NBS-LRR). Using an iterative search process we identified NBS-LRR gene models within the E. grandis genome. We characterized the gene models and identified their genomic arrangement. The gene expression patterns were examined in E. grandis clones, challenged with a fungal pathogen (Chrysoporthe austroafricana) and insect pest (Leptocybe invasa). One thousand two hundred and fifteen putative NBS-LRR coding sequences were located which aligned into two large classes, Toll or interleukin-1 receptor (TIR) and coiled-coil (CC) based on NB-ARC domains. NBS-LRR gene-rich regions were identified with 76% organized in clusters of three or more genes. A further 272 putative incomplete resistance genes were also identified. We determined that E. grandis has a higher ratio of TIR to CC classed genes compared to other woody plant species as well as a smaller percentage of single NBS-LRR genes. Transcriptome profiles indicated expression hotspots, within physical clusters, including expression of many incomplete genes. The clustering of putative NBS-LRR genes correlates with differential expression responses in resistant and susceptible plants indicating functional relevance for the physical arrangement of this gene family. This analysis of the repertoire and expression of E. grandis putative NBS-LRR genes provides an important resource for the identification of novel and functional R-genes; a key objective for strategies to enhance resilience.
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Affiliation(s)
- Nanette Christie
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, Genomics Research Institute, University of PretoriaPretoria, South Africa
| | - Peri A. Tobias
- Department of Plant and Food Sciences, Faculty of Agriculture and Environment, University of SydneyNSW, Australia
| | - Sanushka Naidoo
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, Genomics Research Institute, University of PretoriaPretoria, South Africa
| | - Carsten Külheim
- Research School of Biology, College of Medicine, Biology and Environment, Australian National UniversityCanberra, ACT, Australia
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Bernoux M, Burdett H, Williams SJ, Zhang X, Chen C, Newell K, Lawrence GJ, Kobe B, Ellis JG, Anderson PA, Dodds PN. Comparative Analysis of the Flax Immune Receptors L6 and L7 Suggests an Equilibrium-Based Switch Activation Model. THE PLANT CELL 2016; 28:146-59. [PMID: 26744216 PMCID: PMC4746675 DOI: 10.1105/tpc.15.00303] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 12/10/2015] [Accepted: 01/06/2016] [Indexed: 05/18/2023]
Abstract
NOD-like receptors (NLRs) are central components of the plant immune system. L6 is a Toll/interleukin-1 receptor (TIR) domain-containing NLR from flax (Linum usitatissimum) conferring immunity to the flax rust fungus. Comparison of L6 to the weaker allele L7 identified two polymorphic regions in the TIR and the nucleotide binding (NB) domains that regulate both effector ligand-dependent and -independent cell death signaling as well as nucleotide binding to the receptor. This suggests that a negative functional interaction between the TIR and NB domains holds L7 in an inactive/ADP-bound state more tightly than L6, hence decreasing its capacity to adopt the active/ATP-bound state and explaining its weaker activity in planta. L6 and L7 variants with a more stable ADP-bound state failed to bind to AvrL567 in yeast two-hybrid assays, while binding was detected to the signaling active variants. This contrasts with current models predicting that effectors bind to inactive receptors to trigger activation. Based on the correlation between nucleotide binding, effector interaction, and immune signaling properties of L6/L7 variants, we propose that NLRs exist in an equilibrium between ON and OFF states and that effector binding to the ON state stabilizes this conformation, thereby shifting the equilibrium toward the active form of the receptor to trigger defense signaling.
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Affiliation(s)
| | - Hayden Burdett
- School of Biological Sciences, Flinders University, Adelaide SA 5001, Australia
| | - Simon J Williams
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane QLD 4072, Australia
| | | | | | - Kim Newell
- CSIRO Agriculture, Canberra ACT 2601, Australia
| | | | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane QLD 4072, Australia
| | | | - Peter A Anderson
- School of Biological Sciences, Flinders University, Adelaide SA 5001, Australia
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Bourras S, McNally KE, Müller MC, Wicker T, Keller B. Avirulence Genes in Cereal Powdery Mildews: The Gene-for-Gene Hypothesis 2.0. FRONTIERS IN PLANT SCIENCE 2016; 7:241. [PMID: 26973683 PMCID: PMC4771761 DOI: 10.3389/fpls.2016.00241] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 02/12/2016] [Indexed: 05/22/2023]
Abstract
The gene-for-gene hypothesis states that for each gene controlling resistance in the host, there is a corresponding, specific gene controlling avirulence in the pathogen. Allelic series of the cereal mildew resistance genes Pm3 and Mla provide an excellent system for genetic and molecular analysis of resistance specificity. Despite this opportunity for molecular research, avirulence genes in mildews remain underexplored. Earlier work in barley powdery mildew (B.g. hordei) has shown that the reaction to some Mla resistance alleles is controlled by multiple genes. Similarly, several genes are involved in the specific interaction of wheat mildew (B.g. tritici) with the Pm3 allelic series. We found that two mildew genes control avirulence on Pm3f: one gene is involved in recognition by the resistance protein as demonstrated by functional studies in wheat and the heterologous host Nicotiana benthamiana. A second gene is a suppressor, and resistance is only observed in mildew genotypes combining the inactive suppressor and the recognized Avr. We propose that such suppressor/avirulence gene combinations provide the basis of specificity in mildews. Depending on the particular gene combinations in a mildew race, different genes will be genetically identified as the "avirulence" gene. Additionally, the observation of two LINE retrotransposon-encoded avirulence genes in B.g. hordei further suggests that the control of avirulence in mildew is more complex than a canonical gene-for-gene interaction. To fully understand the mildew-cereal interactions, more knowledge on avirulence determinants is needed and we propose ways how this can be achieved based on recent advances in the field.
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58
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Ray S, Singh PK, Gupta DK, Mahato AK, Sarkar C, Rathour R, Singh NK, Sharma TR. Analysis of Magnaporthe oryzae Genome Reveals a Fungal Effector, Which Is Able to Induce Resistance Response in Transgenic Rice Line Containing Resistance Gene, Pi54. FRONTIERS IN PLANT SCIENCE 2016; 7:1140. [PMID: 27551285 PMCID: PMC4976503 DOI: 10.3389/fpls.2016.01140] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/18/2016] [Indexed: 05/04/2023]
Abstract
Rice blast caused by Magnaporthe oryzae is one of the most important diseases of rice. Pi54, a rice gene that imparts resistance to M. oryzae isolates prevalent in India, was already cloned but its avirulent counterpart in the pathogen was not known. After decoding the whole genome of an avirulent isolate of M. oryzae, we predicted 11440 protein coding genes and then identified four candidate effector proteins which are exclusively expressed in the infectious structure, appresoria. In silico protein modeling followed by interaction analysis between Pi54 protein model and selected four candidate effector proteins models revealed that Mo-01947_9 protein model encoded by a gene located at chromosome 4 of M. oryzae, interacted best at the Leucine Rich Repeat domain of Pi54 protein model. Yeast-two-hybrid analysis showed that Mo-01947_9 protein physically interacts with Pi54 protein. Nicotiana benthamiana leaf infiltration assay confirmed induction of hypersensitive response in the presence of Pi54 gene in a heterologous system. Genetic complementation test also proved that Mo-01947_9 protein induces avirulence response in the pathogen in presence of Pi54 gene. Here, we report identification and cloning of a new fungal effector gene which interacts with blast resistance gene Pi54 in rice.
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Affiliation(s)
- Soham Ray
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Pankaj K. Singh
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Deepak K. Gupta
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Ajay K. Mahato
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Chiranjib Sarkar
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Rajeev Rathour
- Chaudhary Sarwan Kumar Himachal Pradesh Agricultural UniversityPalampur, India
| | - Nagendra K. Singh
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
| | - Tilak R. Sharma
- National Research Centre on Plant Biotechnology, Pusa CampusNew Delhi, India
- *Correspondence: Tilak R. Sharma,
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Su J, Wang W, Han J, Chen S, Wang C, Zeng L, Feng A, Yang J, Zhou B, Zhu X. Functional divergence of duplicated genes results in a novel blast resistance gene Pi50 at the Pi2/9 locus. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2015; 128:2213-25. [PMID: 26183036 DOI: 10.1007/s00122-015-2579-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/27/2015] [Indexed: 05/03/2023]
Abstract
We characterized a novel blast resistance gene Pi50 at the Pi2/9 locus; Pi50 is derived from functional divergence of duplicated genes. The unique features of Pi50 should facilitate its use in rice breeding and improve our understanding of the evolution of resistance specificities. Rice blast disease, caused by the fungal pathogen Magnaporthe oryzae, poses constant, major threats to stable rice production worldwide. The deployment of broad-spectrum resistance (R) genes provides the most effective and economical means for disease control. In this study, we characterize the broad-spectrum R gene Pi50 at the Pi2/9 locus, which is embedded within a tandem cluster of 12 genes encoding proteins with nucleotide-binding site and leucine-rich repeat (NBS-LRR) domains. In contrast with other Pi2/9 locus, the Pi50 cluster contains four duplicated genes (Pi50_NBS4_1 to 4) with extremely high nucleotide sequence similarity. Moreover, these duplicated genes encode two kinds of proteins (Pi50_NBS4_1/2 and Pi50_NBS4_3/4) that differ by four amino acids. Complementation tests and resistance spectrum analyses revealed that Pi50_NBS4_1/2, not Pi50_NBS4_3/4, control the novel resistance specificity as observed in the Pi50 near isogenic line, NIL-e1. Pi50 shares greater than 96 % amino acid sequence identity with each of three other R proteins, i.e., Pi9, Piz-t, and Pi2, and has amino acid changes predominantly within the LRR region. The identification of Pi50 with its novel resistance specificity will facilitate the dissection of mechanisms behind the divergence and evolution of different resistance specificities at the Pi2/9 locus.
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Affiliation(s)
- Jing Su
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Wenjuan Wang
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Jingluan Han
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Shen Chen
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Congying Wang
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Liexian Zeng
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Aiqing Feng
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Jianyuan Yang
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Bo Zhou
- Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, DAPO Box 7777, 1031, Metro Manila, Philippines.
| | - Xiaoyuan Zhu
- Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China.
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60
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Identification of novel alleles of the rice blast resistance gene Pi54. Sci Rep 2015; 5:15678. [PMID: 26498172 PMCID: PMC4620502 DOI: 10.1038/srep15678] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 10/01/2015] [Indexed: 12/13/2022] Open
Abstract
Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.
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61
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Vasudevan K, Gruissem W, Bhullar NK. Identification of novel alleles of the rice blast resistance gene Pi54. Sci Rep 2015. [PMID: 26498172 DOI: 10.1038/srep15678.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023] Open
Abstract
Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.
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Affiliation(s)
- Kumar Vasudevan
- Plant Biotechnology, Department of Biology, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Wilhelm Gruissem
- Plant Biotechnology, Department of Biology, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Navreet K Bhullar
- Plant Biotechnology, Department of Biology, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
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62
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Bourras S, McNally KE, Ben-David R, Parlange F, Roffler S, Praz CR, Oberhaensli S, Menardo F, Stirnweis D, Frenkel Z, Schaefer LK, Flückiger S, Treier G, Herren G, Korol AB, Wicker T, Keller B. Multiple Avirulence Loci and Allele-Specific Effector Recognition Control the Pm3 Race-Specific Resistance of Wheat to Powdery Mildew. THE PLANT CELL 2015; 27:2991-3012. [PMID: 26452600 PMCID: PMC4682313 DOI: 10.1105/tpc.15.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 09/01/2015] [Accepted: 09/11/2015] [Indexed: 05/20/2023]
Abstract
In cereals, several mildew resistance genes occur as large allelic series; for example, in wheat (Triticum aestivum and Triticum turgidum), 17 functional Pm3 alleles confer agronomically important race-specific resistance to powdery mildew (Blumeria graminis). The molecular basis of race specificity has been characterized in wheat, but little is known about the corresponding avirulence genes in powdery mildew. Here, we dissected the genetics of avirulence for six Pm3 alleles and found that three major Avr loci affect avirulence, with a common locus_1 involved in all AvrPm3-Pm3 interactions. We cloned the effector gene AvrPm3(a2/f2) from locus_2, which is recognized by the Pm3a and Pm3f alleles. Induction of a Pm3 allele-dependent hypersensitive response in transient assays in Nicotiana benthamiana and in wheat demonstrated specificity. Gene expression analysis of Bcg1 (encoded by locus_1) and AvrPm3 (a2/f2) revealed significant differences between isolates, indicating that in addition to protein polymorphisms, expression levels play a role in avirulence. We propose a model for race specificity involving three components: an allele-specific avirulence effector, a resistance gene allele, and a pathogen-encoded suppressor of avirulence. Thus, whereas a genetically simple allelic series controls specificity in the plant host, recognition on the pathogen side is more complex, allowing flexible evolutionary responses and adaptation to resistance genes.
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Affiliation(s)
- Salim Bourras
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | | | - Roi Ben-David
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Francis Parlange
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Stefan Roffler
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | | | - Simone Oberhaensli
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Fabrizio Menardo
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Daniel Stirnweis
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Zeev Frenkel
- Institute of Evolution, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | | | - Simon Flückiger
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Georges Treier
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Gerhard Herren
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Abraham B Korol
- Institute of Evolution, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | - Thomas Wicker
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Beat Keller
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
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Chaudhari P, Ahmed B, Joly DL, Germain H. Effector biology during biotrophic invasion of plant cells. Virulence 2015; 5:703-9. [PMID: 25513771 PMCID: PMC4189876 DOI: 10.4161/viru.29652] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Several obligate biotrophic phytopathogens, namely oomycetes and fungi, invade and feed on living plant cells through specialized structures known as haustoria. Deploying an arsenal of secreted proteins called effectors, these pathogens balance their parasitic propagation by subverting plant immunity without sacrificing host cells. Such secreted proteins, which are thought to be delivered by haustoria, conceivably reprogram host cells and instigate structural modifications, in addition to the modulation of various cellular processes. As effectors represent tools to assist disease resistance breeding, this short review provides a bird’s eye view on the relationship between the virulence function of effectors and their subcellular localization in host cells.
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Affiliation(s)
- Prateek Chaudhari
- a Groupe de Recherche en Biologie Végétale; Département de Chimie, Biochimie et Physique; Université du Québec à Trois-Rivières; Trois-Rivières, QC Canada
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64
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Sarris PF, Duxbury Z, Huh SU, Ma Y, Segonzac C, Sklenar J, Derbyshire P, Cevik V, Rallapalli G, Saucet SB, Wirthmueller L, Menke FLH, Sohn KH, Jones JDG. A Plant Immune Receptor Detects Pathogen Effectors that Target WRKY Transcription Factors. Cell 2015; 161:1089-1100. [PMID: 26000484 DOI: 10.1016/j.cell.2015.04.024] [Citation(s) in RCA: 342] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/06/2015] [Accepted: 04/03/2015] [Indexed: 12/28/2022]
Abstract
Defense against pathogens in multicellular eukaryotes depends on intracellular immune receptors, yet surveillance by these receptors is poorly understood. Several plant nucleotide-binding, leucine-rich repeat (NB-LRR) immune receptors carry fusions with other protein domains. The Arabidopsis RRS1-R NB-LRR protein carries a C-terminal WRKY DNA binding domain and forms a receptor complex with RPS4, another NB-LRR protein. This complex detects the bacterial effectors AvrRps4 or PopP2 and then activates defense. Both bacterial proteins interact with the RRS1 WRKY domain, and PopP2 acetylates lysines to block DNA binding. PopP2 and AvrRps4 interact with other WRKY domain-containing proteins, suggesting these effectors interfere with WRKY transcription factor-dependent defense, and RPS4/RRS1 has integrated a "decoy" domain that enables detection of effectors that target WRKY proteins. We propose that NB-LRR receptor pairs, one member of which carries an additional protein domain, enable perception of pathogen effectors whose function is to target that domain.
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Affiliation(s)
| | - Zane Duxbury
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Sung Un Huh
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Yan Ma
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Cécile Segonzac
- Bio-protection Research Centre, Institute of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Jan Sklenar
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Paul Derbyshire
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Volkan Cevik
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | | | - Simon B Saucet
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | | | - Frank L H Menke
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Kee Hoon Sohn
- Bio-protection Research Centre, Institute of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
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65
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Two linked pairs of Arabidopsis TNL resistance genes independently confer recognition of bacterial effector AvrRps4. Nat Commun 2015; 6:6338. [PMID: 25744164 DOI: 10.1038/ncomms7338] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/20/2015] [Indexed: 01/01/2023] Open
Abstract
Plant immunity requires recognition of pathogen effectors by intracellular NB-LRR immune receptors encoded by Resistance (R) genes. Most R proteins recognize a specific effector, but some function in pairs that recognize multiple effectors. Arabidopsis thaliana TIR-NB-LRR proteins RRS1-R and RPS4 together recognize two bacterial effectors, AvrRps4 from Pseudomonas syringae and PopP2 from Ralstonia solanacearum. However, AvrRps4, but not PopP2, is recognized in rrs1/rps4 mutants. We reveal an R gene pair that resembles and is linked to RRS1/RPS4, designated as RRS1B/RPS4B, which confers recognition of AvrRps4 but not PopP2. Like RRS1/RPS4, RRS1B/RPS4B proteins associate and activate defence genes upon AvrRps4 recognition. Inappropriate combinations (RRS1/RPS4B or RRS1B/RPS4) are non-functional and this specificity is not TIR domain dependent. Distinct putative orthologues of both pairs are maintained in the genomes of Arabidopsis thaliana relatives and are likely derived from a common ancestor pair. Our results provide novel insights into paired R gene function and evolution.
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66
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Recognition and activation domains contribute to allele-specific responses of an Arabidopsis NLR receptor to an oomycete effector protein. PLoS Pathog 2015; 11:e1004665. [PMID: 25671309 PMCID: PMC4335498 DOI: 10.1371/journal.ppat.1004665] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 01/06/2015] [Indexed: 11/19/2022] Open
Abstract
In plants, specific recognition of pathogen effector proteins by nucleotide-binding leucine-rich repeat (NLR) receptors leads to activation of immune responses. RPP1, an NLR from Arabidopsis thaliana, recognizes the effector ATR1, from the oomycete pathogen Hyaloperonospora arabidopsidis, by direct association via C-terminal leucine-rich repeats (LRRs). Two RPP1 alleles, RPP1-NdA and RPP1-WsB, have narrow and broad recognition spectra, respectively, with RPP1-NdA recognizing a subset of the ATR1 variants recognized by RPP1-WsB. In this work, we further characterized direct effector recognition through random mutagenesis of an unrecognized ATR1 allele, ATR1-Cala2, screening for gain-of-recognition phenotypes in a tobacco hypersensitive response assay. We identified ATR1 mutants that a) confirm surface-exposed residues contribute to recognition by RPP1, and b) are recognized by and activate the narrow-spectrum allele RPP1-NdA, but not RPP1-WsB, in co-immunoprecipitation and bacterial growth inhibition assays. Thus, RPP1 alleles have distinct recognition specificities, rather than simply different sensitivity to activation. Using chimeric RPP1 constructs, we showed that RPP1-NdA LRRs were sufficient for allele-specific recognition (association with ATR1), but insufficient for receptor activation in the form of HR. Additional inclusion of the RPP1-NdA ARC2 subdomain, from the central NB-ARC domain, was required for a full range of activation specificity. Thus, cooperation between recognition and activation domains seems to be essential for NLR function.
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67
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Cui H, Tsuda K, Parker JE. Effector-triggered immunity: from pathogen perception to robust defense. ANNUAL REVIEW OF PLANT BIOLOGY 2015; 66:487-511. [PMID: 25494461 DOI: 10.1146/annurev-arplant-050213-040012] [Citation(s) in RCA: 752] [Impact Index Per Article: 83.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In plant innate immunity, individual cells have the capacity to sense and respond to pathogen attack. Intracellular recognition mechanisms have evolved to intercept perturbations by pathogen virulence factors (effectors) early in host infection and convert it to rapid defense. One key to resistance success is a polymorphic family of intracellular nucleotide-binding/leucine-rich-repeat (NLR) receptors that detect effector interference in different parts of the cell. Effector-activated NLRs connect, in various ways, to a conserved basal resistance network in order to transcriptionally boost defense programs. Effector-triggered immunity displays remarkable robustness against pathogen disturbance, in part by employing compensatory mechanisms within the defense network. Also, the mobility of some NLRs and coordination of resistance pathways across cell compartments provides flexibility to fine-tune immune outputs. Furthermore, a number of NLRs function close to the nuclear chromatin by balancing actions of defense-repressing and defense-activating transcription factors to program cells dynamically for effective disease resistance.
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Affiliation(s)
- Haitao Cui
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany; , ,
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68
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Dogimont C, Chovelon V, Pauquet J, Boualem A, Bendahmane A. The Vat locus encodes for a CC-NBS-LRR protein that confers resistance to Aphis gossypii infestation and A. gossypii-mediated virus resistance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:993-1004. [PMID: 25283874 DOI: 10.1111/tpj.12690] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/23/2014] [Accepted: 09/26/2014] [Indexed: 05/06/2023]
Abstract
Aphis gossypii is a polyphagous sucking aphid and a vector for many viruses. In Cucumis melo, a dominant locus, Vat, confers a high level of resistance to Aphis gossypii infestation and to viruses transmitted by this vector. To investigate the mechanism underlying this double resistance, we first genetically dissected the Vat locus. We delimited the double resistance to a single gene that encodes for a coiled-coil-nucleotide-binding-site-leucine-rich repeat (CC-NBS-LRR) protein type. To validate the genetic data, transgenic lines expressing the Vat gene were generated and assessed for the double resistance. In this analysis, Vat-transgenic plants were resistant to A. gossypii infestation as well as A. gossypii-mediated virus transmission. When the plants were infected mechanically, virus infection occurred on both transgenic and non-transgenic control plants. These results confirmed that the cloned CC-NBS-LRR gene mediates both resistance to aphid infestation and virus infection using A. gossypii as a vector. This resistance also invokes a separate recognition and response phases in which the recognition phase involves the interaction of an elicitor molecule from the aphid and Vat from the plant. The response phase is not specific and blocks both aphid infestation and virus infection. Sequence analysis of Vat alleles suggests a major role of an unusual conserved LRR repeat in the recognition of A. gossypii.
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Affiliation(s)
- Catherine Dogimont
- INRA, UR 1052, Unité de Génétique et d'Amélioration des Fruits et Légumes, BP 94, F-84143, Montfavet, France
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69
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Wu W, Wang L, Zhang S, Li Z, Zhang Y, Lin F, Pan Q. Stepwise arms race between AvrPik and Pik alleles in the rice blast pathosystem. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:759-69. [PMID: 24742074 DOI: 10.1094/mpmi-02-14-0046-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
A stepwise mutation that occurred in both pathogens and their respective hosts has played a seminal role in the co-evolutionary arms race evolution in diverse pathosystems. The process driven by rice blast AvrPik and Pik alleles was investigated through population genetic and evolutionary approaches. The genetic diversity of the non-signal domain of AvrPik was higher than that in its signal peptide domain. Positive selection for particular AvrPik alleles in the northeastern region of China was stronger than in the south. The perfect relationship between the functional lineages and AvrPik allele-specific pathotypes was established by ruling out the nonfunctional lineages derived from additional copies. Only four alleles conditioning stepwise pathotypes were detected in natural populations, which were likely created by only one evolutionary pathway with three recognizable mutation steps. Two non-stepwise pathotypes were determined by two blocks in a network constructed by all 16 possible alleles, indicating that a natural evolution process can be artificially changed by a combination of specific single-nucleotide polymorphisms. Assuming that AvrPik evolution has been largely driven by host selection, the co-evolutionary stepwise relationships between AvrPik and Pik was established. The experimental validation of stepwise mutation is required for the development of sustainable management strategies against plant disease.
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70
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Hulbert S, Pumphrey M. A time for more booms and fewer busts? Unraveling cereal-rust interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:207-14. [PMID: 24499028 DOI: 10.1094/mpmi-09-13-0295-fi] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Recent advances in our understanding of the nature of resistance genes and rust fungus genomics are providing some insight into the basis of resistance and susceptibility to rust diseases in our cereal crops. Characterized rust resistance genes, for the most part, resemble other resistance genes that interact with effectors intracellularly, but some have unique features. Characterization of rust effectors is just beginning but genomic information and technical advances in rust functional genomics will accelerate their characterization. The ephemeral nature of resistance in past varieties has made the design of cultivars with durable resistance a major focus for geneticists and cereal breeders. This includes strategies for deploying race-specific resistance genes that prolong their effects and methods of predicting which will be difficult for the pathogen to defeat. Identification of resistance genes with race-nonspecific effects is another strategy where recent breakthroughs have been made. Routinely combining the numerous genes required for complex resistance, whether specific or nonspecific, in elite cultivars remains a primary constraint to realizing durable resistance in most programs.
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71
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Petre B, Joly DL, Duplessis S. Effector proteins of rust fungi. FRONTIERS IN PLANT SCIENCE 2014; 5:416. [PMID: 25191335 PMCID: PMC4139122 DOI: 10.3389/fpls.2014.00416] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 08/04/2014] [Indexed: 05/19/2023]
Abstract
Rust fungi include many species that are devastating crop pathogens. To develop resistant plants, a better understanding of rust virulence factors, or effector proteins, is needed. Thus far, only six rust effector proteins have been described: AvrP123, AvrP4, AvrL567, AvrM, RTP1, and PGTAUSPE-10-1. Although some are well established model proteins used to investigate mechanisms of immune receptor activation (avirulence activities) or entry into plant cells, how they work inside host tissues to promote fungal growth remains unknown. The genome sequences of four rust fungi (two Melampsoraceae and two Pucciniaceae) have been analyzed so far. Genome-wide analyses of these species, as well as transcriptomics performed on a broader range of rust fungi, revealed hundreds of small secreted proteins considered as rust candidate secreted effector proteins (CSEPs). The rust community now needs high-throughput approaches (effectoromics) to accelerate effector discovery/characterization and to better understand how they function in planta. However, this task is challenging due to the non-amenability of rust pathosystems (obligate biotrophs infecting crop plants) to traditional molecular genetic approaches mainly due to difficulties in culturing these species in vitro. The use of heterologous approaches should be promoted in the future.
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Affiliation(s)
- Benjamin Petre
- INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy LorraineChampenoux, France
- UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, Université de LorraineVandoeuvre-lès-Nancy, France
- The Sainsbury Laboratory, Norwich Research ParkNorwich, UK
| | - David L. Joly
- Département de Biologie, Université de MonctonMoncton, NB, Canada
| | - Sébastien Duplessis
- INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy LorraineChampenoux, France
- UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, Université de LorraineVandoeuvre-lès-Nancy, France
- *Correspondence: Sébastien Duplessis, INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, Champenoux 54280, France e-mail:
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Abstract
Live-cell imaging assisted by fluorescent markers has been fundamental to understanding the focused secretory 'warfare' that occurs between plants and biotrophic pathogens that feed on living plant cells. Pathogens succeed through the spatiotemporal deployment of a remarkably diverse range of effector proteins to control plant defences and cellular processes. Some effectors can be secreted by appressoria even before host penetration, many enter living plant cells where they target diverse subcellular compartments and others move into neighbouring cells to prepare them before invasion. This Review summarizes the latest advances in our understanding of the cell biology of biotrophic interactions between plants and their eukaryotic filamentous pathogens based on in planta analyses of effectors.
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73
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Hurni S, Brunner S, Buchmann G, Herren G, Jordan T, Krukowski P, Wicker T, Yahiaoui N, Mago R, Keller B. Rye Pm8 and wheat Pm3 are orthologous genes and show evolutionary conservation of resistance function against powdery mildew. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:957-69. [PMID: 24124925 DOI: 10.1111/tpj.12345] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/25/2013] [Accepted: 10/04/2013] [Indexed: 05/18/2023]
Abstract
The improvement of wheat through breeding has relied strongly on the use of genetic material from related wild and domesticated grass species. The 1RS chromosome arm from rye was introgressed into wheat and crossed into many wheat lines, as it improves yield and fungal disease resistance. Pm8 is a powdery mildew resistance gene on 1RS which, after widespread agricultural cultivation, is now widely overcome by adapted mildew races. Here we show by homology-based cloning and subsequent physical and genetic mapping that Pm8 is the rye orthologue of the Pm3 allelic series of mildew resistance genes in wheat. The cloned gene was functionally validated as Pm8 by transient, single-cell expression analysis and stable transformation. Sequence analysis revealed a complex mosaic of ancient haplotypes among Pm3- and Pm8-like genes from different members of the Triticeae. These results show that the two genes have evolved independently after the divergence of the species 7.5 million years ago and kept their function in mildew resistance. During this long time span the co-evolving pathogens have not overcome these genes, which is in strong contrast to the breakdown of Pm8 resistance since its introduction into commercial wheat 70 years ago. Sequence comparison revealed that evolutionary pressure acted on the same subdomains and sequence features of the two orthologous genes. This suggests that they recognize directly or indirectly the same pathogen effectors that have been conserved in the powdery mildews of wheat and rye.
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Affiliation(s)
- Severine Hurni
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
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74
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Wan L, Zhang X, Williams SJ, Ve T, Bernoux M, Sohn KH, Jones JDG, Dodds PN, Kobe B. Crystallization and preliminary X-ray diffraction analyses of the TIR domains of three TIR-NB-LRR proteins that are involved in disease resistance in Arabidopsis thaliana. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1275-80. [PMID: 24192368 PMCID: PMC3818052 DOI: 10.1107/s1744309113026614] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 09/26/2013] [Indexed: 05/27/2023]
Abstract
The Toll/interleukin-1 receptor (TIR) domain is a protein-protein interaction domain that is found in both animal and plant immune receptors. The N-terminal TIR domain from the nucleotide-binding (NB)-leucine-rich repeat (LRR) class of plant disease-resistance (R) proteins has been shown to play an important role in defence signalling. Recently, the crystal structure of the TIR domain from flax R protein L6 was determined and this structure, combined with functional studies, demonstrated that TIR-domain homodimerization is a requirement for function of the R protein L6. To advance the molecular understanding of the function of TIR domains in R-protein signalling, the protein expression, purification, crystallization and X-ray diffraction analyses of the TIR domains of the Arabidopsis thaliana R proteins RPS4 (resistance to Pseudomonas syringae 4) and RRS1 (resistance to Ralstonia solanacearum 1) and the resistance-like protein SNC1 (suppressor of npr1-1, constitutive 1) are reported here. RPS4 and RRS1 function cooperatively as a dual resistance-protein system that prevents infection by three distinct pathogens. SNC1 is implicated in resistance pathways in Arabidopsis and is believed to be involved in transcriptional regulation through its interaction with the transcriptional corepressor TPR1 (Topless-related 1). The TIR domains of all three proteins have successfully been expressed and purified as soluble proteins in Escherichia coli. Plate-like crystals of the RPS4 TIR domain were obtained using PEG 3350 as a precipitant; they diffracted X-rays to 2.05 Å resolution, had the symmetry of space group P1 and analysis of the Matthews coefficient suggested that there were four molecules per asymmetric unit. Tetragonal crystals of the RRS1 TIR domain were obtained using ammonium sulfate as a precipitant; they diffracted X-rays to 1.75 Å resolution, had the symmetry of space group P4(1)2(1)2 or P4(3)2(1)2 and were most likely to contain one molecule per asymmetric unit. Crystals of the SNC1 TIR domain were obtained using PEG 3350 as a precipitant; they diffracted X-rays to 2.20 Å resolution and had the symmetry of space group P4(1)2(1)2 or P4(3)2(1)2, with two molecules predicted per asymmetric unit. These results provide a good foundation to advance the molecular and structural understanding of the function of the TIR domain in plant innate immunity.
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Affiliation(s)
- Li Wan
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology) and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Xiaoxiao Zhang
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology) and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Simon J. Williams
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology) and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology) and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Maud Bernoux
- CSIRO Plant Industry, Canberra, ACT 2601, Australia
| | - Kee Hoon Sohn
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, England
| | | | | | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology) and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
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75
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Qi D, Innes RW. Recent Advances in Plant NLR Structure, Function, Localization, and Signaling. Front Immunol 2013; 4:348. [PMID: 24155748 PMCID: PMC3801107 DOI: 10.3389/fimmu.2013.00348] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 10/09/2013] [Indexed: 12/14/2022] Open
Abstract
Nucleotide-binding domain leucine-rich repeat (NLR) proteins play a central role in the innate immune systems of plants and vertebrates. In plants, NLR proteins function as intracellular receptors that detect pathogen effector proteins directly, or indirectly by recognizing effector-induced modifications to other host proteins. NLR activation triggers a suite of defense responses associated with programed cell death (PCD). The molecular mechanisms underlying NLR activation, and how activation is translated into defense responses, have been particularly challenging to elucidate in plants. Recent reports, however, are beginning to shed some light. It is becoming clear that plant NLR proteins are targeted to diverse sub-cellular locations, likely depending on the locations where the effectors are detected. These reports also indicate that some NLRs re-localize following effector detection, while others do not, and such relocalization may reflect differences in signaling pathways. There have also been recent advances in understanding the structure of plant NLR proteins, with crystal structures now available for the N-terminal domains of two well-studied NLRs, a coiled-coil (CC) domain and a Toll-interleukin Receptor (TIR). Significant improvements in molecular modeling have enabled more informed structure-function studies, illuminating roles of intra- and inter-molecular interactions in NLR activation regulation. Several independent studies also suggest that intracellular trafficking is involved in NLR-mediated resistance. Lastly, progress is being made on identifying transcriptional regulatory complexes activated by NLRs. Current models for how plant NLR proteins are activated and how they induce defenses are discussed, with an emphasis on what remains to be determined.
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Affiliation(s)
- Dong Qi
- Department of Biology, Indiana University , Bloomington, IN , USA
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76
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Zhu Q, Bennetzen JL, Smith SM. Isolation and diversity analysis of resistance gene homologues from switchgrass. G3 (BETHESDA, MD.) 2013; 3:1031-42. [PMID: 23589518 PMCID: PMC3689800 DOI: 10.1534/g3.112.005447] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/10/2013] [Indexed: 12/31/2022]
Abstract
Resistance gene homologs (RGHs) were isolated from the switchgrass variety Alamo by a combination of polymerase chain reaction and expressed sequence tag (EST) database mining. Fifty-eight RGHs were isolated by polymerase chain reaction and 295 RGHs were identified in 424,545 switchgrass ESTs. Four nucleotide binding site--leucine-rich repeat RGHs were selected to investigate RGH haplotypic diversity in seven switchgrass varieties chosen for their representation of a broad range of the switchgrass germplasm. Lowland and upland ecotypes were found to be less similar, even from nearby populations, than were more distant populations with similar growth environments. Most (83.5%) of the variability in these four RGHs was found to be attributable to the within-population component. The difference in nucleotide diversity between and within populations was observed to be small, whereas this diversity is maintained to similar degrees at both population and ecotype levels. The results also revealed that the analyzed RGHs were under positive selection in the studied switchgrass accessions. Intragenic recombination was detected in switchgrass RGHs, thereby demonstrating an active genetic process that has the potential to generate new resistance genes with new specificities that might act against newly-arising pathogen races.
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Affiliation(s)
- Qihui Zhu
- Department of Genetics, The University of Georgia, Athens, Georgia 30602
| | | | - Shavannor M. Smith
- Department of Plant Pathology, The University of Georgia, Athens, Georgia 30602
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77
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Chang C, Yu D, Jiao J, Jing S, Schulze-Lefert P, Shen QH. Barley MLA immune receptors directly interfere with antagonistically acting transcription factors to initiate disease resistance signaling. THE PLANT CELL 2013; 25:1158-73. [PMID: 23532068 PMCID: PMC3634683 DOI: 10.1105/tpc.113.109942] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/01/2013] [Accepted: 03/11/2013] [Indexed: 05/18/2023]
Abstract
The nucleotide binding domain and Leucine-rich repeat (NLR)-containing proteins in plants and animals mediate pathogen sensing inside host cells and mount innate immune responses against microbial pathogens. The barley (Hordeum vulgare) mildew A (MLA) locus encodes coiled-coil (CC)-type NLRs mediating disease resistance against the powdery mildew pathogen Blumeria graminis. Here, we report direct interactions between MLA and two antagonistically acting transcription factors, MYB6 and WRKY1. The N-terminal CC signaling domain of MLA interacts with MYB6 to stimulate its DNA binding activity. MYB6 functions as a positive regulator of basal and MLA-mediated immunity responses to B. graminis. MYB6 DNA binding is antagonized by direct association with WRKY1 repressor, which in turn also interacts with the MLA CC domain. The activated form of full-length MLA10 receptor is needed to release MYB6 activator from WRKY1 repression and to stimulate MYB6-dependent gene expression. This implies that, while sequestered by the WRKY1 repressor in the presence of the resting immune receptor, MYB6 acts as an immediate and positive postactivation signaling component of the active state of MLA during transcriptional reprogramming for innate immune responses.
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Affiliation(s)
- Cheng Chang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Graduate University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deshui Yu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Graduate University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Jiao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Graduate University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shaojuan Jing
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany
| | - Qian-Hua Shen
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Address correspondence to
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