1
|
López A, van Kan JAL, Beenen HG, Dolcet-Sanjuan R, Teixidó N, Torres R, Vilanova L. Evaluation of cell death-inducing activity of Monilinia spp. effectors in several plants using a modified TRV expression system. FRONTIERS IN PLANT SCIENCE 2024; 15:1428613. [PMID: 39220017 PMCID: PMC11362074 DOI: 10.3389/fpls.2024.1428613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 07/29/2024] [Indexed: 09/04/2024]
Abstract
Introduction Brown rot is the most important fungal disease affecting stone fruit and it is mainly caused by Monilinia fructicola, M. laxa and M. fructigena. Monilinia spp. are necrotrophic plant pathogens with the ability to induce plant cell death by the secretion of different phytotoxic molecules, including proteins or metabolites that are collectively referred to as necrotrophic effectors (NEs). Methods We exploited the genomes of M. fructicola, M. laxa and M. fructigena to identify their common group of secreted effector proteins and tested the ability of a selected set of effectors to induce cell death in Nicotiana benthamiana, Solanum lycopersicum and Prunus spp. leaves. Results Fourteen candidate effector genes of M. fructicola, which displayed high expression during infection, were transiently expressed in plants by agroinfiltration using a modified Tobacco Rattle Virus (TRV)-based expression system. Some, but not all, effectors triggered leaf discoloration or cell death in N. benthamiana and S. lycopersicum, which are non-hosts for Monilinia and in Prunus spp., which are the natural hosts. The effector MFRU_030g00190 induced cell death in almost all Prunus genotypes tested, but not in the Solanaceous plants, while MFRU_014g02060, which is an ortholog to BcNep1, caused necrosis in all plant species tested. Conclusion This method provides opportunities for screening Prunus germplasm with Monilinia effector proteins, to serve as a tool for identifying genetic loci that confer susceptibility to brown rot disease.
Collapse
Affiliation(s)
- Anselmo López
- IRTA, Postharvest Programme, Edifici Fruitcentre, Parc Agrobiotech Lleida, Lleida, Catalonia, Spain
| | - Jan A. L. van Kan
- Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands
| | - Henriek G. Beenen
- Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands
| | - Ramon Dolcet-Sanjuan
- IRTA, Plant In Vitro Culture Laboratory, Fruticulture Program, Parc Agrobiotech Lleida, Lleida, Catalonia, Spain
| | - Neus Teixidó
- IRTA, Postharvest Programme, Edifici Fruitcentre, Parc Agrobiotech Lleida, Lleida, Catalonia, Spain
| | - Rosario Torres
- IRTA, Postharvest Programme, Edifici Fruitcentre, Parc Agrobiotech Lleida, Lleida, Catalonia, Spain
| | - Laura Vilanova
- IRTA, Postharvest Programme, Edifici Fruitcentre, Parc Agrobiotech Lleida, Lleida, Catalonia, Spain
- Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands
| |
Collapse
|
2
|
Morikawa S, Verdonk C, John E, Lenzo L, Sbaraini N, Turo C, Li H, Jiang D, Chooi YH, Tan KC. The Velvet transcription factor PnVeA regulates necrotrophic effectors and secondary metabolism in the wheat pathogen Parastagonospora nodorum. BMC Microbiol 2024; 24:299. [PMID: 39127645 PMCID: PMC11316297 DOI: 10.1186/s12866-024-03454-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024] Open
Abstract
The fungus Parastagonospora nodorum causes septoria nodorum blotch on wheat. The role of the fungal Velvet-family transcription factor VeA in P. nodorum development and virulence was investigated here. Deletion of the P. nodorum VeA ortholog, PnVeA, resulted in growth abnormalities including pigmentation, abolished asexual sporulation and highly reduced virulence on wheat. Comparative RNA-Seq and RT-PCR analyses revealed that the deletion of PnVeA also decoupled the expression of major necrotrophic effector genes. In addition, the deletion of PnVeA resulted in an up-regulation of four predicted secondary metabolite (SM) gene clusters. Using liquid-chromatography mass-spectrometry, it was observed that one of the SM gene clusters led to an accumulation of the mycotoxin alternariol. PnVeA is essential for asexual sporulation, full virulence, secondary metabolism and necrotrophic effector regulation.
Collapse
Affiliation(s)
- Shota Morikawa
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Callum Verdonk
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Evan John
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115201, Taiwan
| | - Leon Lenzo
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Nicolau Sbaraini
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Chala Turo
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Hang Li
- School of Molecular Sciences, University of Western Australia, Perth, Australia
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - David Jiang
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Yit-Heng Chooi
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia.
| |
Collapse
|
3
|
Derbyshire MC, Raffaele S. Till death do us pair: Co-evolution of plant-necrotroph interactions. CURRENT OPINION IN PLANT BIOLOGY 2023; 76:102457. [PMID: 37852141 DOI: 10.1016/j.pbi.2023.102457] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/18/2023] [Accepted: 08/29/2023] [Indexed: 10/20/2023]
Abstract
Plants use programmed cell death as a potent defense response against biotrophic pathogens that require living host cells to thrive. However, cell death can promote infection by necrotrophic pathogens. This discrepancy creates specific co-evolutionary dynamics in the interaction between plants and necrotrophs. Necrotrophic pathogens produce diverse cell death-inducing effectors that act redundantly on several plant targets and sometimes suppress plant immune responses as an additional function. Plants use surface receptors that recognize necrotrophic effectors to increase quantitative disease resistance, some of which evolved independently in several plant lineages. Co-evolution has shaped molecular mechanisms involved in plant-necrotroph interactions into robust systems, relying on degenerate and multifunctional modules, general-purpose components, and compartmentalized functioning.
Collapse
Affiliation(s)
- Mark C Derbyshire
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Sylvain Raffaele
- Université de Toulouse, INRAE, CNRS, Laboratoire des Interactions Plantes Micro-organismes Environnement (LIPME), 31326, Castanet-Tolosan, France.
| |
Collapse
|
4
|
Gupta PK, Vasistha NK, Singh S, Joshi AK. Genetics and breeding for resistance against four leaf spot diseases in wheat ( Triticum aestivum L.). FRONTIERS IN PLANT SCIENCE 2023; 14:1023824. [PMID: 37063191 PMCID: PMC10096043 DOI: 10.3389/fpls.2023.1023824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 02/28/2023] [Indexed: 06/19/2023]
Abstract
In wheat, major yield losses are caused by a variety of diseases including rusts, spike diseases, leaf spot and root diseases. The genetics of resistance against all these diseases have been studied in great detail and utilized for breeding resistant cultivars. The resistance against leaf spot diseases caused by each individual necrotroph/hemi-biotroph involves a complex system involving resistance (R) genes, sensitivity (S) genes, small secreted protein (SSP) genes and quantitative resistance loci (QRLs). This review deals with resistance for the following four-leaf spot diseases: (i) Septoria nodorum blotch (SNB) caused by Parastagonospora nodorum; (ii) Tan spot (TS) caused by Pyrenophora tritici-repentis; (iii) Spot blotch (SB) caused by Bipolaris sorokiniana and (iv) Septoria tritici blotch (STB) caused by Zymoseptoria tritici.
Collapse
Affiliation(s)
- Pushpendra Kumar Gupta
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
- Murdoch’s Centre for Crop and Food Innovation, Murdoch University, Murdoch, WA, Australia
- Borlaug Institute for South Asia (BISA), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
| | - Neeraj Kumar Vasistha
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
- Department of Genetics-Plant Breeding and Biotechnology, Dr Khem Singh Gill, Akal College of Agriculture, Eternal University, Baru Sahib, Sirmour, India
| | - Sahadev Singh
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
| | - Arun Kumar Joshi
- Borlaug Institute for South Asia (BISA), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
- The International Maize and Wheat Improvement Center (CIMMYT), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
| |
Collapse
|
5
|
John E, Jacques S, Phan HTT, Liu L, Pereira D, Croll D, Singh KB, Oliver RP, Tan KC. Variability in an effector gene promoter of a necrotrophic fungal pathogen dictates epistasis and effector-triggered susceptibility in wheat. PLoS Pathog 2022; 18:e1010149. [PMID: 34990464 PMCID: PMC8735624 DOI: 10.1371/journal.ppat.1010149] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/26/2021] [Indexed: 12/31/2022] Open
Abstract
The fungus Parastagonospora nodorum uses proteinaceous necrotrophic effectors (NEs) to induce tissue necrosis on wheat leaves during infection, leading to the symptoms of septoria nodorum blotch (SNB). The NEs Tox1 and Tox3 induce necrosis on wheat possessing the dominant susceptibility genes Snn1 and Snn3B1/Snn3D1, respectively. We previously observed that Tox1 is epistatic to the expression of Tox3 and a quantitative trait locus (QTL) on chromosome 2A that contributes to SNB resistance/susceptibility. The expression of Tox1 is significantly higher in the Australian strain SN15 compared to the American strain SN4. Inspection of the Tox1 promoter region revealed a 401 bp promoter genetic element in SN4 positioned 267 bp upstream of the start codon that is absent in SN15, called PE401. Analysis of the world-wide P. nodorum population revealed that a high proportion of Northern Hemisphere isolates possess PE401 whereas the opposite was observed in representative P. nodorum isolates from Australia and South Africa. The presence of PE401 removed the epistatic effect of Tox1 on the contribution of the SNB 2A QTL but not Tox3. PE401 was introduced into the Tox1 promoter regulatory region in SN15 to test for direct regulatory roles. Tox1 expression was markedly reduced in the presence of PE401. This suggests a repressor molecule(s) binds PE401 and inhibits Tox1 transcription. Infection assays also demonstrated that P. nodorum which lacks PE401 is more pathogenic on Snn1 wheat varieties than P. nodorum carrying PE401. An infection competition assay between P. nodorum isogenic strains with and without PE401 indicated that the higher Tox1-expressing strain rescued the reduced virulence of the lower Tox1-expressing strain on Snn1 wheat. Our study demonstrated that Tox1 exhibits both 'selfish' and 'altruistic' characteristics. This offers an insight into a complex NE-NE interaction that is occurring within the P. nodorum population. The importance of PE401 in breeding for SNB resistance in wheat is discussed.
Collapse
Affiliation(s)
- Evan John
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Curtin University, Bentley, Perth, Western Australia, Australia
| | - Silke Jacques
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Curtin University, Bentley, Perth, Western Australia, Australia
| | - Huyen T. T. Phan
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Curtin University, Bentley, Perth, Western Australia, Australia
| | - Lifang Liu
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Curtin University, Bentley, Perth, Western Australia, Australia
| | - Danilo Pereira
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Karam B. Singh
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, Western Australia, Australia
| | | | - Kar-Chun Tan
- Centre for Crop and Disease Management, Curtin University, Bentley, Perth, Western Australia, Australia
- Curtin University, Bentley, Perth, Western Australia, Australia
| |
Collapse
|
6
|
Katoch S, Sharma V, Sharma D, Salwan R, Rana SK. Biology and molecular interactions of Parastagonospora nodorum blotch of wheat. PLANTA 2021; 255:21. [PMID: 34914013 DOI: 10.1007/s00425-021-03796-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/14/2021] [Indexed: 06/14/2023]
Abstract
Parastagonospora nodorum is one of the important necrotrophic pathogens of wheat which causes severe economical loss to crop yield. So far, a number of effectors of Parastagonospora nodorum origin and their target interacting genes on the host plant have been characterized. Since targeting effector-sensitive gene carefully can be helpful in breeding for resistance. Therefore, constant efforts are required to further characterize the effectors, their interacting genes, and underlying biochemical pathways. Furthermore, to develop effective counter-strategies against emerging diseases, continuous efforts are required to determine the qualitative resistance that demands to screen of diverse genotypes for host resistance. Stagonospora nodorum blotch also refers to as Stagonospora glume blotch and leaf is caused by Parastagonospora nodorum. The pathogen deploys necrotrophic effectors for the establishment and development on wheat plants. The necrotrophic effectors and their interaction with host receptors lead to the establishment of infection on leaves and extensive lesions formation which either results in host cell death or suppression/activation of host defence mechanisms. The wheat Stagonospora nodorum interaction involves a set of nine host gene-necrotrophic effector interactions. Out of these, Snn1-SnTox1, Tsn1-SnToxA and Snn-SnTox3 are one of the most studied interaction, due to its role in the suppression of reactive oxygen species production, regulating the cytokinin content through ethylene-dependent wayduring initial infection stage. Further, although the molecular basis is not fully unveiled, these effectors regulate the redox state and influence the ethylene biosynthesis in infected wheat plants. Here, we have discussed the biology of the wheat pathogen Parastagonospora nodorum, role of its necrotrophic effectors and their interacting sensitivity genes on the redox state, how they hijack the resistance mechanisms, hormonal regulated immunity and other signalling pathways in susceptible wheat plants. The information generated from effectors and their corresponding sensitivity genes and other biological processes could be utilized effectively for disease management strategies.
Collapse
Affiliation(s)
- Shabnam Katoch
- Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India
| | - Vivek Sharma
- University Centre for Research and Development, Chandigarh University, Gharuan, 140413, Punjab, India.
| | - Devender Sharma
- Crop Improvement Division, ICAR-Vivekananda Parvatiya Krishi Anusandhan Sansthan, Almora, Uttarakhand, India
| | - Richa Salwan
- College of Horticulture and Forestry, Neri, Dr YS Parmar University of Horticulture and Forestry, Solan, Hamirpur, 177 001, India
| | - S K Rana
- Department of Plant Pathology, CSK HPKV Palampur, Palampur, 176062, Himachal Pradesh, India
| |
Collapse
|
7
|
Bertazzoni S, Jones DAB, Phan HT, Tan KC, Hane JK. Chromosome-level genome assembly and manually-curated proteome of model necrotroph Parastagonospora nodorum Sn15 reveals a genome-wide trove of candidate effector homologs, and redundancy of virulence-related functions within an accessory chromosome. BMC Genomics 2021; 22:382. [PMID: 34034667 PMCID: PMC8146201 DOI: 10.1186/s12864-021-07699-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 05/11/2021] [Indexed: 11/19/2022] Open
Abstract
Background The fungus Parastagonospora nodorum causes septoria nodorum blotch (SNB) of wheat (Triticum aestivum) and is a model species for necrotrophic plant pathogens. The genome assembly of reference isolate Sn15 was first reported in 2007. P. nodorum infection is promoted by its production of proteinaceous necrotrophic effectors, three of which are characterised – ToxA, Tox1 and Tox3. Results A chromosome-scale genome assembly of P. nodorum Australian reference isolate Sn15, which combined long read sequencing, optical mapping and manual curation, produced 23 chromosomes with 21 chromosomes possessing both telomeres. New transcriptome data were combined with fungal-specific gene prediction techniques and manual curation to produce a high-quality predicted gene annotation dataset, which comprises 13,869 high confidence genes, and an additional 2534 lower confidence genes retained to assist pathogenicity effector discovery. Comparison to a panel of 31 internationally-sourced isolates identified multiple hotspots within the Sn15 genome for mutation or presence-absence variation, which was used to enhance subsequent effector prediction. Effector prediction resulted in 257 candidates, of which 98 higher-ranked candidates were selected for in-depth analysis and revealed a wealth of functions related to pathogenicity. Additionally, 11 out of the 98 candidates also exhibited orthology conservation patterns that suggested lateral gene transfer with other cereal-pathogenic fungal species. Analysis of the pan-genome indicated the smallest chromosome of 0.4 Mbp length to be an accessory chromosome (AC23). AC23 was notably absent from an avirulent isolate and is predominated by mutation hotspots with an increase in non-synonymous mutations relative to other chromosomes. Surprisingly, AC23 was deficient in effector candidates, but contained several predicted genes with redundant pathogenicity-related functions. Conclusions We present an updated series of genomic resources for P. nodorum Sn15 – an important reference isolate and model necrotroph – with a comprehensive survey of its predicted pathogenicity content. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07699-8.
Collapse
Affiliation(s)
| | - Darcy A B Jones
- Centre for Crop & Disease Management, Curtin University, Perth, Australia
| | - Huyen T Phan
- Centre for Crop & Disease Management, Curtin University, Perth, Australia.
| | - Kar-Chun Tan
- Centre for Crop & Disease Management, Curtin University, Perth, Australia.
| | - James K Hane
- Centre for Crop & Disease Management, Curtin University, Perth, Australia. .,Curtin Institute for Computation, Curtin University, Perth, Australia.
| |
Collapse
|
8
|
GWAS analysis reveals distinct pathogenicity profiles of Australian Parastagonospora nodorum isolates and identification of marker-trait-associations to septoria nodorum blotch. Sci Rep 2021; 11:10085. [PMID: 33980869 PMCID: PMC8115087 DOI: 10.1038/s41598-021-87829-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/05/2021] [Indexed: 12/25/2022] Open
Abstract
The fungus Parastagonospora nodorum is the causal agent of septoria nodorum leaf blotch (SNB) and glume blotch which are common in many wheat growing regions in the world. The disease is complex and could be explained by multiple interactions between necrotrophic effectors secreted by the pathogen and matching susceptibility genes in wheat. An Australian P. nodorum population was clustered into five groups with contrasting properties. This study was set to identify their pathogenicity profiles using a diverse wheat panel of 134 accessions which are insensitive to SnToxA and SnTox1 in both in vitro and in vivo conditions. SNB seedling resistance/susceptibility to five representative isolates from the five clusters, responses to crude culture-filtrates (CFs) of three isolates and sensitivity to SnTox3 semi-purified effector together with 11,455 SNP markers have been used for linkage disequilibrium (LD) and association analyses. While quantitative trait loci (QTL) on 1D, 2A, 2B, 4B, 5B, 6A, 6B, 7A, 7D chromosomes were consistently detected across isolates and conditions, distinct patterns and isolate specific QTL were also observed among these isolates. In this study, SnTox3–Snn3-B1 interaction for the first time in Australia and SnTox3–Snn3-D1 interaction for the first time in bread wheat were found active using wild-type isolates. These findings could be due to new SnTox3 haplotype/isoform and exotic CIMMYT/ICARDA and Vavilov germplasm used, respectively. This study could provide useful information for dissecting novel and different SNB disease components, helping to prioritise research targets and contributing valuable information on genetic loci/markers for marker-assisted selection in SNB resistance wheat breeding programme.
Collapse
|
9
|
Vilanova L, Valero-Jiménez CA, van Kan JA. Deciphering the Monilinia fructicola Genome to Discover Effector Genes Possibly Involved in Virulence. Genes (Basel) 2021; 12:568. [PMID: 33919788 PMCID: PMC8070815 DOI: 10.3390/genes12040568] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 12/18/2022] Open
Abstract
Brown rot is the most economically important fungal disease of stone fruits and is primarily caused by Monilinia laxa and Monlinia fructicola. Both species co-occur in European orchards although M. fructicola is considered to cause the most severe yield losses in stone fruit. This study aimed to generate a high-quality genome of M. fructicola and to exploit it to identify genes that may contribute to pathogen virulence. PacBio sequencing technology was used to assemble the genome of M. fructicola. Manual structural curation of gene models, supported by RNA-Seq, and functional annotation of the proteome yielded 10,086 trustworthy gene models. The genome was examined for the presence of genes that encode secreted proteins and more specifically effector proteins. A set of 134 putative effectors was defined. Several effector genes were cloned into Agrobacterium tumefaciens for transient expression in Nicotiana benthamiana plants, and some of them triggered necrotic lesions. Studying effectors and their biological properties will help to better understand the interaction between M. fructicola and its stone fruit host plants.
Collapse
Affiliation(s)
- Laura Vilanova
- Laboratory of Phytopathology, Wageningen University, 6708 PB Wageningen, The Netherlands; (L.V.); (C.A.V.-J.)
- IRTA, Postharvest Programme, Edifici Fruitcentre, Parc Científic i Tecnològic Agroalimentari de Lleida, Parc de Gardeny, 25003 Lleida, Catalonia, Spain
| | - Claudio A. Valero-Jiménez
- Laboratory of Phytopathology, Wageningen University, 6708 PB Wageningen, The Netherlands; (L.V.); (C.A.V.-J.)
| | - Jan A.L. van Kan
- Laboratory of Phytopathology, Wageningen University, 6708 PB Wageningen, The Netherlands; (L.V.); (C.A.V.-J.)
| |
Collapse
|
10
|
Li Q, Wang B, Yu J, Dou D. Pathogen-informed breeding for crop disease resistance. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2021; 63:305-311. [PMID: 33095498 DOI: 10.1111/jipb.13029] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
The development of durable and broad-spectrum resistance is an economical and eco-friendly approach to control crop diseases for sustainable agricultural production. Emerging knowledge of the molecular basis of pathogenesis and plant-pathogen interactions has contributed to the development of novel pathogen-informed breeding strategies beyond the limits imposed by conventional breeding. Here, we review the current status of pathogen-assisted resistance-related gene cloning. We also describe how pathogen effector proteins can be used to identify resistance resources and to inform cultivar deployment. Finally, we summarize the main approaches for pathogen-directed plant improvement, including transgenesis and genome editing. Thus, we describe the emerging role of pathogen-related studies in the breeding of disease-resistant varieties, and propose innovative pathogen-informed strategies for future applications.
Collapse
Affiliation(s)
- Qi Li
- Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Bi Wang
- Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China
| | - Jinping Yu
- Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China
| | - Daolong Dou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| |
Collapse
|
11
|
Muria-Gonzalez MJ, Yeng Y, Breen S, Mead O, Wang C, Chooi YH, Barrow RA, Solomon PS. Volatile Molecules Secreted by the Wheat Pathogen Parastagonospora nodorum Are Involved in Development and Phytotoxicity. Front Microbiol 2020; 11:466. [PMID: 32269554 PMCID: PMC7111460 DOI: 10.3389/fmicb.2020.00466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/04/2020] [Indexed: 12/01/2022] Open
Abstract
Septoria nodorum blotch is a major disease of wheat caused by the fungus Parastagonospora nodorum. Recent studies have demonstrated that secondary metabolites, including polyketides and non-ribosomal peptides, produced by the pathogen play important roles in disease and development. However, there is currently no knowledge on the composition or biological activity of the volatile organic compounds (VOCs) secreted by P. nodorum. To address this, we undertook a series of growth and phytotoxicity assays and demonstrated that P. nodorum VOCs inhibited bacterial growth, were phytotoxic and suppressed self-growth. Mass spectrometry analysis revealed that 3-methyl-1-butanol, 2-methyl-1-butanol, 2-methyl-1-propanol, and 2-phenylethanol were dominant in the VOC mixture and phenotypic assays using these short chain alcohols confirmed that they were phytotoxic. Further analysis of the VOCs also identified the presence of multiple sesquiterpenes of which four were identified via mass spectrometry and nuclear magnetic resonance as β-elemene, α-cyperone, eudesma-4,11-diene and acora-4,9-diene. Subsequent reverse genetics studies were able to link these molecules to corresponding sesquiterpene synthases in the P. nodorum genome. However, despite extensive testing, these molecules were not involved in either of the growth inhibition or phytotoxicity phenotypes previously observed. Plant assays using mutants of the pathogen lacking the synthetic genes revealed that the identified sesquiterpenes were not required for disease formation on wheat leaves. Collectively, these data have significantly extended our knowledge of the VOCs in fungi and provided the basis for further dissecting the roles of sesquiterpenes in plant disease.
Collapse
Affiliation(s)
| | - Yeannie Yeng
- Research School of Biology, ACT, Australian National University, Canberra, ACT, Australia
- Department of Oral Biology and Biomedical Sciences, MAHSA University, Selangor, Malaysia
| | - Susan Breen
- Research School of Biology, ACT, Australian National University, Canberra, ACT, Australia
| | - Oliver Mead
- Research School of Biology, ACT, Australian National University, Canberra, ACT, Australia
| | - Chen Wang
- Research School of Biology, ACT, Australian National University, Canberra, ACT, Australia
| | - Yi-Heng Chooi
- School of Molecular Sciences, University of Western Australia, Perth, WA, Australia
| | - Russell A. Barrow
- Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW, Australia
- Plus 3 Australia Pty Ltd., Hawker, ACT, Australia
| | - Peter S. Solomon
- Research School of Biology, ACT, Australian National University, Canberra, ACT, Australia
| |
Collapse
|
12
|
Lin M, Corsi B, Ficke A, Tan KC, Cockram J, Lillemo M. Genetic mapping using a wheat multi-founder population reveals a locus on chromosome 2A controlling resistance to both leaf and glume blotch caused by the necrotrophic fungal pathogen Parastagonospora nodorum. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2020; 133:785-808. [PMID: 31996971 PMCID: PMC7021668 DOI: 10.1007/s00122-019-03507-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 12/10/2019] [Indexed: 05/19/2023]
Abstract
KEY MESSAGE A locus on wheat chromosome 2A was found to control field resistance to both leaf and glume blotch caused by the necrotrophic fungal pathogen Parastagonospora nodorum. The necrotrophic fungal pathogen Parastagonospora nodorum is the causal agent of Septoria nodorum leaf blotch and glume blotch, which are common wheat (Triticum aestivum L.) diseases in humid and temperate areas. Susceptibility to Septoria nodorum leaf blotch can partly be explained by sensitivity to corresponding P. nodorum necrotrophic effectors (NEs). Susceptibility to glume blotch is also quantitative; however, the underlying genetics have not been studied in detail. Here, we genetically map resistance/susceptibility loci to leaf and glume blotch using an eight-founder wheat multiparent advanced generation intercross population. The population was assessed in six field trials across two sites and 4 years. Seedling infiltration and inoculation assays using three P. nodorum isolates were also carried out, in order to compare quantitative trait loci (QTL) identified under controlled conditions with those identified in the field. Three significant field resistance QTL were identified on chromosomes 2A and 6A, while four significant seedling resistance QTL were detected on chromosomes 2D, 5B and 7D. Among these, QSnb.niab-2A.3 for field resistance to both leaf blotch and glume blotch was detected in Norway and the UK. Colocation with a QTL for seedling reactions against culture filtrate from a Norwegian P. nodorum isolate indicated the QTL could be caused by a novel NE sensitivity. The consistency of this QTL for leaf blotch at the seedling and adult plant stages and culture filtrate infiltration was confirmed by haplotype analysis. However, opposite effects for the leaf blotch and glume blotch reactions suggest that different genetic mechanisms may be involved.
Collapse
Affiliation(s)
- Min Lin
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway
| | - Beatrice Corsi
- John Bingham Laboratory, NIAB, Huntingdon Road, Cambridge, CB3 0LE, UK
| | - Andrea Ficke
- Norwegian Institute of Bioeconomy Research, Høgskoleveien 7, 1433, Ås, Norway
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - James Cockram
- John Bingham Laboratory, NIAB, Huntingdon Road, Cambridge, CB3 0LE, UK
| | - Morten Lillemo
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway.
| |
Collapse
|
13
|
Cowger C, Ward B, Brown-Guedira G, Brown JKM. Role of Effector-Sensitivity Gene Interactions and Durability of Quantitative Resistance to Septoria Nodorum Blotch in Eastern U.S. Wheat. FRONTIERS IN PLANT SCIENCE 2020; 11:155. [PMID: 32210986 PMCID: PMC7067980 DOI: 10.3389/fpls.2020.00155] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/31/2020] [Indexed: 05/02/2023]
Abstract
Important advances have been made in understanding the relationship of necrotrophic effectors (NE) and host sensitivity (Snn) genes in the Parastagonospora nodorum-wheat pathosystem. Yet much remains to be learned about the role of these interactions in determining wheat resistance levels in the field, and there is mixed evidence on whether breeding programs have selected against Snn genes due to their role in conferring susceptibility. SNB occurs ubiquitously in the U.S. Atlantic seaboard, and the environment is especially well suited to field studies of resistance to natural P. nodorum populations, as there are no other important wheat leaf blights. Insights into the nature of SNB resistance have been gleaned from multi-year data on phenotypes and markers in cultivars representative of the region's germplasm. In this perspective article, we review the evidence that in this eastern region of the U.S., wheat cultivars have durable quantitative SNB resistance and Snn-NE interactions are of limited importance. This conclusion is discussed in light of the relevant available information from other parts of the world.
Collapse
Affiliation(s)
- Christina Cowger
- U.S. Department of Agriculture – Agricultural Research Service, North Carolina State University, Raleigh, NC, United States
- *Correspondence: Christina Cowger,
| | - Brian Ward
- U.S. Department of Agriculture – Agricultural Research Service, North Carolina State University, Raleigh, NC, United States
| | - Gina Brown-Guedira
- U.S. Department of Agriculture – Agricultural Research Service, North Carolina State University, Raleigh, NC, United States
| | - James K. M. Brown
- Department of Crop Genetics, John Innes Centre, Norwich, United Kingdom
| |
Collapse
|
14
|
A specific fungal transcription factor controls effector gene expression and orchestrates the establishment of the necrotrophic pathogen lifestyle on wheat. Sci Rep 2019; 9:15884. [PMID: 31685928 PMCID: PMC6828707 DOI: 10.1038/s41598-019-52444-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/17/2019] [Indexed: 12/14/2022] Open
Abstract
The fungus Parastagonospora nodorum infects wheat through the use of necrotrophic effector (NE) proteins that cause host-specific tissue necrosis. The Zn2Cys6 transcription factor PnPf2 positively regulates NE gene expression and is required for virulence on wheat. Little is known about other downstream targets of PnPf2. We compared the transcriptomes of the P. nodorum wildtype and a strain deleted in PnPf2 (pf2-69) during in vitro growth and host infection to further elucidate targets of PnPf2 signalling. Gene ontology enrichment analysis of the differentially expressed (DE) genes revealed that genes associated with plant cell wall degradation and proteolysis were enriched in down-regulated DE gene sets in pf2-69 compared to SN15. In contrast, genes associated with redox control, nutrient and ion transport were up-regulated in the mutant. Further analysis of the DE gene set revealed that PnPf2 positively regulates twelve genes that encode effector-like proteins. Two of these genes encode proteins with homology to previously characterised effectors in other fungal phytopathogens. In addition to modulating effector gene expression, PnPf2 may play a broader role in the establishment of a necrotrophic lifestyle by orchestrating the expression of genes associated with plant cell wall degradation and nutrient assimilation.
Collapse
|
15
|
Ruud AK, Dieseth JA, Ficke A, Furuki E, Phan HTT, Oliver RP, Tan KC, Lillemo M. Genome-Wide Association Mapping of Resistance to Septoria Nodorum Leaf Blotch in a Nordic Spring Wheat Collection. THE PLANT GENOME 2019; 12:1-15. [PMID: 33016591 DOI: 10.3835/plantgenome2018.12.0105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 05/06/2019] [Indexed: 05/12/2023]
Abstract
First genome-wide association mapping of adult plant Septoria nodorum blotch resistance. Some adult plant resistance loci were shared with seedling resistance loci. Other adult plant resistance loci were significant across environments. Resistant haplotypes were identified, which can be used for breeding. Parastagonospora nodorum is the causal agent of Septoria nodorum leaf blotch (SNB) in wheat (Triticum aestivum L.). It is the most important leaf blotch pathogen in Norwegian spring wheat. Several quantitative trait loci (QTL) for SNB susceptibility have been identified. Some of these QTL are the result of underlying gene-for-gene interactions involving necrotrophic effectors (NEs) and corresponding sensitivity (Snn) genes. A collection of diverse spring wheat lines was evaluated for SNB resistance and susceptibility over seven growing seasons in the field. In addition, wheat seedlings were inoculated and infiltrated with culture filtrates (CFs) from four single spore isolates and infiltrated with semipurified NEs (SnToxA, SnTox1, and SnTox3) under greenhouse conditions. In adult plants, the most stable SNB resistance QTL were located on chromosomes 2B, 2D, 4A, 4B, 5A, 6B, 7A, and 7B. The QTL on chromosome 2D was effective most years in the field. At the seedling stage, the most significant QTL after inoculation were located on chromosomes 1A, 1B, 3A, 4B, 5B, 6B, 7A, and 7B. The QTL on chromosomes 3A and 6B were significant both after inoculation and CF infiltration, indicating the presence of novel NE-Snn interactions. The QTL on chromosomes 4B and 7A were significant in both seedlings and adult plants. Correlations between SnToxA sensitivity and disease severity in the field were significant. To our knowledge, this is the first genome-wide association mapping study (GWAS) to investigate SNB resistance at the adult plant stage under field conditions.
Collapse
Affiliation(s)
- Anja Karine Ruud
- Dep. of Plant Sciences, Norwegian Univ. of Life Sciences, Post Box 5003, NO-1432, ÅS, Norway
- Faculty of Science and Technology, Dep. of Molecular Biology and Genetics, Aarhus Univ, 4200, Slagelse, Denmark
| | - Jon Arne Dieseth
- Graminor, AS, Bjørke Gård, Hommelstadvegen 60, NO-2322, Ridabu, Norway
| | - Andrea Ficke
- Division of Biotechnology and Plant Health, Norwegian Inst. of Bioeconomy Research, P.O. Box 115, NO-1431, ÅS, Norway
| | - Eiko Furuki
- Centre for Crop and Disease Management, Dep. of Environment & Agriculture, Curtin Univ., Bentley, Western Australia, Australia
| | - Huyen T T Phan
- Centre for Crop and Disease Management, Dep. of Environment & Agriculture, Curtin Univ., Bentley, Western Australia, Australia
| | - Richard P Oliver
- Centre for Crop and Disease Management, Dep. of Environment & Agriculture, Curtin Univ., Bentley, Western Australia, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, Dep. of Environment & Agriculture, Curtin Univ., Bentley, Western Australia, Australia
| | - Morten Lillemo
- Dep. of Plant Sciences, Norwegian Univ. of Life Sciences, Post Box 5003, NO-1432, ÅS, Norway
| |
Collapse
|
16
|
Biotechnological potential of engineering pathogen effector proteins for use in plant disease management. Biotechnol Adv 2019; 37:107387. [DOI: 10.1016/j.biotechadv.2019.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 04/18/2019] [Accepted: 04/20/2019] [Indexed: 11/19/2022]
|
17
|
Zhang W, Zhu X, Zhang M, Shi G, Liu Z, Cai X. Chromosome engineering-mediated introgression and molecular mapping of novel Aegilops speltoides-derived resistance genes for tan spot and Septoria nodorum blotch diseases in wheat. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:2605-2614. [PMID: 31183521 DOI: 10.1007/s00122-019-03374-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/06/2019] [Indexed: 06/09/2023]
Abstract
We identified, mapped and introduced novel Aegilops speltoides-derived resistance genes for tan spot and SNB diseases into wheat, enhancing understanding and utilization of host resistance to both diseases in wheat. Tan spot and Septoria nodorum blotch (SNB) are two important fungal diseases of wheat. Resistance to these diseases is often observed as the lack of sensitivity to the necrotrophic effectors (NE) produced by the fungal pathogens and thus exhibits a recessive inheritance pattern. In this study, we identified novel genes for resistance to tan spot and SNB on Aegilops speltoides (2n = 2x = 14, genome SS) chromosome 2S. These genes confer dominant resistance in the wheat background, indicating a distinct NE-independent mechanism of resistance. Ae. speltoides chromosome 2S was engineered for resistance gene introgression and molecular mapping by inducing meiotic homoeologous recombination with wheat chromosome 2B. Twenty representative 2B-2S recombinants were evaluated for reaction to tan spot and SNB and were delineated by genomic in situ hybridization and high-throughput wheat 90 K SNP assay. The resistance genes physically mapped to the sub-telomeric region (~ 8 Mb) on the short arm of chromosome 2S and designated TsrAes1 for tan spot resistance and SnbAes1 for SNB resistance. In addition, we developed SNP-derived PCR markers closely linked to TsrAes1/SnbAes1 for marker-assisted selection in wheat breeding. TsrAes1 and SnbAes1 are the first set of NE-independent tan spot, and SNB resistance genes are identified from Ae. speltoides. The 2SS-2BS·2BL recombinants with minimal amounts of Ae. speltoides chromatin containing TsrAes1/SnbAes1 were produced for germplasm development, making the wild species-derived resistance genes usable in wheat breeding. This will strengthen and diversify resistance of wheat to tan spot and SNB and facilitate understanding of resistance to these two diseases.
Collapse
Affiliation(s)
- Wei Zhang
- Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Xianwen Zhu
- Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Mingyi Zhang
- Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Gongjun Shi
- Department of Plant Pathology, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Zhaohui Liu
- Department of Plant Pathology, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Xiwen Cai
- Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA.
| |
Collapse
|
18
|
Prasad P, Savadi S, Bhardwaj SC, Gangwar OP, Kumar S. Rust pathogen effectors: perspectives in resistance breeding. PLANTA 2019; 250:1-22. [PMID: 30980247 DOI: 10.1007/s00425-019-03167-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
Identification and functional characterization of plant pathogen effectors promise to ameliorate future research and develop effective and sustainable strategies for controlling or containing crop diseases. Wheat is the second most important food crop of the world after rice. Rust pathogens, one of the major biotic stresses in wheat production, are capable of threatening the world food security. Understanding the molecular basis of plant-pathogen interactions is essential for devising novel strategies for resistance breeding and disease management. Now, it has been established that effectors, the proteins secreted by pathogens, play a key role in plant-pathogen interactions. Therefore, effector biology has emerged as one of the most important research fields in plant biology. Recent advances in genomics and bioinformatics have allowed identification of a large repertoire of candidate effectors, while the evolving high-throughput tools have continued to assist in their functional characterization. The repertoires of effectors have become an important resource for better understanding of effector biology of pathosystems and resistance breeding of crop plants. In recent years, a significant progress has been made in the field of rust effector biology. This review describes the recent advances in effector biology of obligate fungal pathogens, identification and functional analysis of wheat rust pathogens effectors and the potential applications of effectors in molecular plant biology and rust resistance breeding in wheat.
Collapse
Affiliation(s)
- Pramod Prasad
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
| | - Siddanna Savadi
- ICAR-Directorate of Cashew Research, Puttur, Karnataka, 574202, India
| | - S C Bhardwaj
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India.
| | - O P Gangwar
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
| | - Subodh Kumar
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
| |
Collapse
|
19
|
Phan HTT, Rybak K, Bertazzoni S, Furuki E, Dinglasan E, Hickey LT, Oliver RP, Tan KC. Novel sources of resistance to Septoria nodorum blotch in the Vavilov wheat collection identified by genome-wide association studies. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2018; 131:1223-1238. [PMID: 29470621 PMCID: PMC5945755 DOI: 10.1007/s00122-018-3073-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/16/2018] [Indexed: 05/02/2023]
Abstract
KEY MESSAGE The fungus Parastagonospora nodorum causes Septoria nodorum blotch (SNB) of wheat. A genetically diverse wheat panel was used to dissect the complexity of SNB and identify novel sources of resistance. The fungus Parastagonospora nodorum is the causal agent of Septoria nodorum blotch (SNB) of wheat. The pathosystem is mediated by multiple fungal necrotrophic effector-host sensitivity gene interactions that include SnToxA-Tsn1, SnTox1-Snn1, and SnTox3-Snn3. A P. nodorum strain lacking SnToxA, SnTox1, and SnTox3 (toxa13) retained wild-type-like ability to infect some modern wheat cultivars, suggesting evidence of other effector-mediated susceptibility gene interactions or the lack of host resistance genes. To identify genomic regions harbouring such loci, we examined a panel of 295 historic wheat accessions from the N. I. Vavilov Institute of Plant Genetic Resources in Russia, which is comprised of genetically diverse landraces and breeding lines registered from 1920 to 1990. The wheat panel was subjected to effector bioassays, infection with P. nodorum wild type (SN15) and toxa13. In general, SN15 was more virulent than toxa13. Insensitivity to all three effectors contributed significantly to resistance against SN15, but not toxa13. Genome-wide association studies using phenotypes from SN15 infection detected quantitative trait loci (QTL) on chromosomes 1BS (Snn1), 2DS, 5AS, 5BS (Snn3), 3AL, 4AL, 4BS, and 7AS. For toxa13 infection, a QTL was detected on 5AS (similar to SN15), plus two additional QTL on 2DL and 7DL. Analysis of resistance phenotypes indicated that plant breeders may have inadvertently selected for effector insensitivity from 1940 onwards. We identify accessions that can be used to develop bi-parental mapping populations to characterise resistance-associated alleles for subsequent introgression into modern bread wheat to minimise the impact of SNB.
Collapse
Affiliation(s)
- Huyen T T Phan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Kasia Rybak
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Stefania Bertazzoni
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Eiko Furuki
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Eric Dinglasan
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia
| | - Lee T Hickey
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia
| | - Richard P Oliver
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia.
| |
Collapse
|
20
|
McDonald MC, Solomon PS. Just the surface: advances in the discovery and characterization of necrotrophic wheat effectors. Curr Opin Microbiol 2018; 46:14-18. [PMID: 29452845 DOI: 10.1016/j.mib.2018.01.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 01/09/2018] [Accepted: 01/31/2018] [Indexed: 02/04/2023]
Abstract
For many years pathogens of wheat have remained poorly understood. Hindered by an inaccessible host and the obligate nature of many of the pathogens, our understanding of these interactions has been limited compared to other more amenable pathosystems. However, breakthroughs over recent years have shed new light on diseases of wheat, particularly those caused by the genetically tractable necrotrophic pathogens. We now understand that many of the necrotrophic fungal pathogens do interact with wheat in a strict gene-for-gene relationship, and that pathogen and host partners in these interactions have now been identified. This improved understanding of necrotrophic effector biology has fundamentally changed the way we consider these important wheat diseases.
Collapse
Affiliation(s)
- Megan C McDonald
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Peter S Solomon
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia.
| |
Collapse
|
21
|
Raffaello T, Asiegbu FO. Small secreted proteins from the necrotrophic conifer pathogen Heterobasidion annosum s.l. (HaSSPs) induce cell death in Nicotiana benthamiana. Sci Rep 2017; 7:8000. [PMID: 28801666 PMCID: PMC5554239 DOI: 10.1038/s41598-017-08010-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 07/05/2017] [Indexed: 01/07/2023] Open
Abstract
The basidiomycete Heterobasidion annosum sensu lato (s.l.) is considered to be one of the most destructive conifer pathogens in the temperate forests of the northern hemisphere. H. annosum is characterized by a dual fungal lifestyle. The fungus grows necrotrophically on living plant cells and saprotrophically on dead wood material. In this study, we screened the H. annosum genome for small secreted proteins (HaSSPs) that could potentially be involved in promoting necrotrophic growth during the fungal infection process. The final list included 58 HaSSPs that lacked predictable protein domains. The transient expression of HaSSP encoding genes revealed the ability of 8 HaSSPs to induce cell chlorosis and cell death in Nicotiana benthamiana. In particular, one protein (HaSSP30) could induce a rapid, strong, and consistent cell death within 2 days post-infiltration. HaSSP30 also increased the transcription of host-defence-related genes in N. benthamiana, which suggested a necrotrophic-specific immune response. This is the first line of evidence demonstrating that the H. annosum genome encodes HaSSPs with the capability to induce plant cell death in a non-host plant.
Collapse
Affiliation(s)
- Tommaso Raffaello
- Department of Forest Sciences, University of Helsinki, Faculty of Agriculture and Forestry, Latokartanonkaari 7, 00014, Helsinki, Finland
| | - Fred O Asiegbu
- Department of Forest Sciences, University of Helsinki, Faculty of Agriculture and Forestry, Latokartanonkaari 7, 00014, Helsinki, Finland.
| |
Collapse
|
22
|
Abstract
The interactions between fungi and plants encompass a spectrum of ecologies ranging from saprotrophy (growth on dead plant material) through pathogenesis (growth of the fungus accompanied by disease on the plant) to symbiosis (growth of the fungus with growth enhancement of the plant). We consider pathogenesis in this article and the key roles played by a range of pathogen-encoded molecules that have collectively become known as effectors.
Collapse
|
23
|
Chooi Y, Zhang G, Hu J, Muria‐Gonzalez MJ, Tran PN, Pettitt A, Maier AG, Barrow RA, Solomon PS. Functional genomics‐guided discovery of a light‐activated phytotoxin in the wheat pathogen
Parastagonospora nodorum
via pathway activation. Environ Microbiol 2017; 19:1975-1986. [DOI: 10.1111/1462-2920.13711] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 02/23/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Yit‐Heng Chooi
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Guozhi Zhang
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Jinyu Hu
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
| | | | - Phuong N. Tran
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Amber Pettitt
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
| | - Alexander G. Maier
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Russell A. Barrow
- Research School of ChemistryAustralian National UniversityCanberra ACT2601 Australia
| | - Peter S. Solomon
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| |
Collapse
|
24
|
Rybak K, See PT, Phan HTT, Syme RA, Moffat CS, Oliver RP, Tan K. A functionally conserved Zn 2 Cys 6 binuclear cluster transcription factor class regulates necrotrophic effector gene expression and host-specific virulence of two major Pleosporales fungal pathogens of wheat. MOLECULAR PLANT PATHOLOGY 2017; 18:420-434. [PMID: 27860150 PMCID: PMC6638278 DOI: 10.1111/mpp.12511] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The fungus Parastagonospora nodorum is the causal agent of Septoria nodorum blotch of wheat (Triticum aestivum). The interaction is mediated by multiple fungal necrotrophic effector-dominant host sensitivity gene interactions. The three best-characterized effector-sensitivity gene systems are SnToxA-Tsn1, SnTox1-Snn1 and SnTox3-Snn3. These effector genes are highly expressed during early infection, but expression decreases as the infection progresses to tissue necrosis and sporulation. However, the mechanism of regulation is unknown. We have identified and functionally characterized a gene, referred to as PnPf2, which encodes a putative zinc finger transcription factor. PnPf2 deletion resulted in the down-regulation of SnToxA and SnTox3 expression. Virulence on Tsn1 and Snn3 wheat cultivars was strongly reduced. The SnTox1-Snn1 interaction remained unaffected. Furthermore, we have also identified and deleted an orthologous PtrPf2 from the tan spot fungus Pyrenophora tritici-repentis which possesses a near-identical ToxA that was acquired from P. nodorum via horizontal gene transfer. PtrPf2 deletion also resulted in the down-regulation of PtrToxA expression and a near-complete loss of virulence on Tsn1 wheat. We have demonstrated, for the first time, evidence for a functionally conserved signalling component that plays a role in the regulation of a common/horizontally transferred effector found in two major fungal pathogens of wheat.
Collapse
Affiliation(s)
- Kasia Rybak
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Pao Theen See
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Huyen T. T. Phan
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Robert A. Syme
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Caroline S. Moffat
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Richard P. Oliver
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| | - Kar‐Chun Tan
- Department of Environment & Agriculture, Centre for Crop and Disease ManagementCurtin University, Bentley, 6102PerthAustralia
| |
Collapse
|
25
|
Zhang X, Nguyen N, Breen S, Outram MA, Dodds PN, Kobe B, Solomon PS, Williams SJ. Production of small cysteine-rich effector proteins in Escherichia coli for structural and functional studies. MOLECULAR PLANT PATHOLOGY 2017; 18:141-151. [PMID: 26915457 PMCID: PMC6638209 DOI: 10.1111/mpp.12385] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 02/22/2016] [Accepted: 02/22/2016] [Indexed: 05/22/2023]
Abstract
Although the lifestyles and infection strategies of plant pathogens are diverse, a prevailing feature is the use of an arsenal of secreted proteins, known as effectors, which aid in microbial infection. In the case of eukaryotic filamentous pathogens, such as fungi and oomycetes, effector proteins are typically dissimilar, at the protein sequence level, to known protein families and functional domains. Consequently, we currently have a limited understanding of how fungal and oomycete effectors promote disease. Protein biochemistry and structural biology are two methods that can contribute greatly to the understanding of protein function. Both techniques are dependent on obtaining proteins that are pure and functional, and generally require the use of heterologous recombinant protein expression systems. Here, we present a general scheme and methodology for the production and characterization of small cysteine-rich (SCR) effectors utilizing Escherichia coli expression systems. Using this approach, we successfully produced cysteine-rich effectors derived from the biotrophic fungal pathogen Melampsora lini and the necrotrophic fungal pathogen Parastagonospora nodorum. Access to functional recombinant proteins facilitated crystallization and functional experiments. These results are discussed in the context of a general workflow that may serve as a template for others interested in understanding the function of SCR effector(s) from their plant pathogen(s) of interest.
Collapse
Affiliation(s)
- Xiaoxiao Zhang
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research CentreUniversity of QueenslandBrisbaneQld4072Australia
| | - Neal Nguyen
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research CentreUniversity of QueenslandBrisbaneQld4072Australia
| | - Susan Breen
- Research School of BiologyThe Australian National UniversityCanberraACT 0200Australia
| | - Megan A. Outram
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research CentreUniversity of QueenslandBrisbaneQld4072Australia
| | | | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research CentreUniversity of QueenslandBrisbaneQld4072Australia
| | - Peter S. Solomon
- Research School of BiologyThe Australian National UniversityCanberraACT 0200Australia
| | - Simon J. Williams
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research CentreUniversity of QueenslandBrisbaneQld4072Australia
| |
Collapse
|
26
|
Phan HTT, Rybak K, Furuki E, Breen S, Solomon PS, Oliver RP, Tan KC. Differential effector gene expression underpins epistasis in a plant fungal disease. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 87:343-54. [PMID: 27133896 PMCID: PMC5053286 DOI: 10.1111/tpj.13203] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 04/18/2016] [Accepted: 04/25/2016] [Indexed: 05/18/2023]
Abstract
Fungal effector-host sensitivity gene interactions play a key role in determining the outcome of septoria nodorum blotch disease (SNB) caused by Parastagonospora nodorum on wheat. The pathosystem is complex and mediated by interaction of multiple fungal necrotrophic effector-host sensitivity gene systems. Three effector sensitivity gene systems are well characterized in this pathosystem; SnToxA-Tsn1, SnTox1-Snn1 and SnTox3-Snn3. We tested a wheat mapping population that segregated for Snn1 and Snn3 with SN15, an aggressive P. nodorum isolate that produces SnToxA, SnTox1 and SnTox3, to study the inheritance of sensitivity to SnTox1 and SnTox3 and disease susceptibility. Interval quantitative trait locus (QTL) mapping showed that the SnTox1-Snn1 interaction was paramount in SNB development on both seedlings and adult plants. No effect of the SnTox3-Snn3 interaction was observed under SN15 infection. The SnTox3-Snn3 interaction was however, detected in a strain of SN15 in which SnTox1 had been deleted (tox1-6). Gene expression analysis indicates increased SnTox3 expression in tox1-6 compared with SN15. This indicates that the failure to detect the SnTox3-Snn3 interaction in SN15 is due - at least in part - to suppressed expression of SnTox3 mediated by SnTox1. Furthermore, infection of the mapping population with a strain deleted in SnToxA, SnTox1 and SnTox3 (toxa13) unmasked a significant SNB QTL on 2DS where the SnTox2 effector sensitivity gene, Snn2, is located. This QTL was not observed in SN15 and tox1-6 infections and thus suggesting that SnToxA and/or SnTox3 were epistatic. Additional QTLs responding to SNB and effectors sensitivity were detected on 2AS1 and 3AL.
Collapse
Affiliation(s)
- Huyen T T Phan
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Kasia Rybak
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Eiko Furuki
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Susan Breen
- Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Peter S Solomon
- Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Richard P Oliver
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia.
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia.
| |
Collapse
|
27
|
John E, Lopez-Ruiz F, Rybak K, Mousley CJ, Oliver RP, Tan KC. Dissecting the role of histidine kinase and HOG1 mitogen-activated protein kinase signalling in stress tolerance and pathogenicity of Parastagonospora nodorum on wheat. MICROBIOLOGY-SGM 2016; 162:1023-1036. [PMID: 26978567 PMCID: PMC5042077 DOI: 10.1099/mic.0.000280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The HOG1 mitogen-activated protein kinase (MAPK) pathway is activated through two-component histidine kinase (HK) signalling. This pathway was first characterized in the budding yeast Saccharomyces cerevisiae as a regulator of osmotolerance. The fungus Parastagonospora nodorum is the causal agent of septoria nodorum blotch of wheat. This pathogen uses host-specific effectors in tandem with general pathogenicity mechanisms to carry out its infection process. Genes showing strong sequence homology to S. cerevisiae HOG1 signalling pathway genes have been identified in the genome of P. nodorum. In this study, we examined the role of the pathway in the virulence of P. nodorum on wheat by disrupting putative pathway component genes: HOG1 (SNOG_13296) MAPK and NIK1 (SNOG_11631) hybrid HK. Mutants deleted in NIK1 and HOG1 were insensitive to dicarboximide and phenylpyrrole fungicides, but not a fungicide that targets ergosterol biosynthesis. Furthermore, both Δnik1 and Δhog1 mutants showed increased sensitivity to hyperosmotic stress. However, HOG1, but not NIK1, is required for tolerance to elevated temperatures. HOG1 deletion conferred increased tolerance to 6-methoxy-2-benzoxazolinone, a cereal phytoalexin. This suggests that the HOG1 signalling pathway is not exclusively associated with NIK1. Both Δnik1 and Δhog1 mutants retained the ability to infect and cause necrotic lesions on wheat. However, we observed that the Δhog1 mutation resulted in reduced production of pycnidia, asexual fruiting bodies that facilitate spore dispersal during late infection. Our study demonstrated the overlapping and distinct roles of a HOG1 MAPK and two-component HK signalling in P. nodorum growth and pathogenicity.
Collapse
Affiliation(s)
- Evan John
- Department of Environment and Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | - Francisco Lopez-Ruiz
- Department of Environment and Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | - Kasia Rybak
- Department of Environment and Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | - Carl J Mousley
- School of Biomedical Sciences, CHIRI Biosciences Research Precinct and Faculty of Health Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Richard P Oliver
- Department of Environment and Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | - Kar-Chun Tan
- Department of Environment and Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| |
Collapse
|
28
|
Chang HX, Domier LL, Radwan O, Yendrek CR, Hudson ME, Hartman GL. Identification of Multiple Phytotoxins Produced by Fusarium virguliforme Including a Phytotoxic Effector (FvNIS1) Associated With Sudden Death Syndrome Foliar Symptoms. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:96-108. [PMID: 26646532 DOI: 10.1094/mpmi-09-15-0219-r] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Sudden death syndrome (SDS) of soybean is caused by a soilborne pathogen, Fusarium virguliforme. Phytotoxins produced by F. virguliforme are translocated from infected roots to leaves, in which they cause SDS foliar symptoms. In this study, additional putative phytotoxins of F. virguliforme were identified, including three secondary metabolites and 11 effectors. While citrinin, fusaric acid, and radicicol induced foliar chlorosis and wilting, Soybean mosaic virus (SMV)-mediated overexpression of F. virguliforme necrosis-inducing secreted protein 1 (FvNIS1) induced SDS foliar symptoms that mimicked the development of foliar symptoms in the field. The expression level of fvnis1 remained steady over time, although foliar symptoms were delayed compared with the expression levels. SMV::FvNIS1 also displayed genotype-specific toxicity to which 75 of 80 soybean cultivars were susceptible. Genome-wide association mapping further identified three single nucleotide polymorphisms at two loci, where three leucine-rich repeat receptor-like protein kinase (LRR-RLK) genes were found. Culture filtrates of fvnis1 knockout mutants displayed a mild reduction in phytotoxicity, indicating that FvNIS1 is one of the phytotoxins responsible for SDS foliar symptoms and may contribute to the quantitative susceptibility of soybean by interacting with the LRR-RLK genes.
Collapse
Affiliation(s)
| | - Leslie L Domier
- 1 University of Illinois
- 2 USDA-Agricultural Research Service; and
| | | | - Craig R Yendrek
- 1 University of Illinois
- 3 Institute for Genomic Biology, Urbana, IL, U.S.A
| | | | - Glen L Hartman
- 1 University of Illinois
- 2 USDA-Agricultural Research Service; and
| |
Collapse
|
29
|
Kettles GJ, Kanyuka K. Dissecting the Molecular Interactions between Wheat and the Fungal Pathogen Zymoseptoria tritici. FRONTIERS IN PLANT SCIENCE 2016; 7:508. [PMID: 27148331 PMCID: PMC4832604 DOI: 10.3389/fpls.2016.00508] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/30/2016] [Indexed: 05/10/2023]
Abstract
The Dothideomycete fungus Zymoseptoria tritici (previously known as Mycosphaerella graminicola and Septoria tritici) is the causative agent of Septoria tritici leaf blotch (STB) disease of wheat (Triticum aestivum L.). In Europe, STB is the most economically damaging disease of wheat, with an estimated ∼€1 billion per year in fungicide expenditure directed toward its control. Here, an overview of our current understanding of the molecular events that occur during Z. tritici infection of wheat leaves is presented. On the host side, this includes the contribution of (1) the pathogen-associated molecular pattern-triggered immunity (PTI) layer of plant defense, and (2) major Stb loci for resistance against Z. tritici. On the pathogen side of the interaction, we consolidate evidence from recent bioinformatic, transcriptomic and proteomic studies that begin to explain the contribution of Z. tritici effector proteins to the biphasic lifestyle of the fungus. This includes the discovery of chitin-binding proteins in the Z. tritici secretome, which contribute to evasion of immune surveillance by this pathogen, and the possible existence of 'necrotrophic' effectors from Z. tritici, which may actively stimulate host recognition in a manner similar to related necrotrophic fungal pathogens. We finish by speculating on how some of these recent fundamental discoveries might be harnessed to help improve resistance to STB in the world's second largest food crop.
Collapse
|