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See PT, Iagallo EM, Marathamuthu KA, Wood B, Aboukhaddour R, Moffat CS. A New ToxA Haplotype in the Wheat Fungal Pathogen Bipolaris sorokiniana. PHYTOPATHOLOGY 2024; 114:1525-1532. [PMID: 38530294 DOI: 10.1094/phyto-10-23-0370-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
The necrotrophic effector ToxA is a well-studied virulence factor produced by several fungal necrotrophs. Initially cloned from the wheat tan spot pathogen Pyrenophora tritici-repentis in 1996, ToxA was found almost a decade later in another fungal pathogen, Parastagonospora nodorum, and its sister species, Parastagonospora pseudonodorum. In 2018, ToxA was detected in a third wheat fungal pathogenic species, Bipolaris sorokiniana, which causes spot blotch disease. However, unlike the case with P. tritici-repentis and P. nodorum, the ToxA in B. sorokiniana has only been investigated in recent years. In this report, five Australian B. sorokiniana isolates were assessed for the presence of ToxA. Four isolates were found to contain ToxA. While one isolate harbored the previously reported ToxA haplotype sequence (ToxA19), three isolates contain a different haplotype, designated herein as ToxA25, which has a nonsynonymous mutation resulting in an amino acid change of glycine to arginine at position 168. Both B. sorokiniana ToxA isoforms, when heterologously expressed in Escherichia coli, exhibited the classic ToxA necrosis-inducing activity on ToxA-sensitive Tsn1 cultivars. Preliminary analysis of the B. sorokiniana isolates in Australian wheat cultivars showed that isolates with ToxA19, ToxA25, or ToxA-deficient displayed various degrees of virulence, with the most aggressive isolates observed for those producing ToxA. Differences in spot blotch disease severity between Tsn1 and tsn1 cultivars were observed; however, this was not limited to the ToxA-producing isolates. The overall results suggest that the virulence of the Australian B. sorokiniana isolates is diverse, with the significance of ToxA-Tsn1 interactions depending on individual isolates.
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Affiliation(s)
- Pao Theen See
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Elyce M Iagallo
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Kalai A Marathamuthu
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Blake Wood
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Reem Aboukhaddour
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada
| | - Caroline S Moffat
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
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Kaur N, Mehl HL, Langston D, Haak DC. Evaluation of Stagonospora Nodorum Blotch Severity and Parastagonospora nodorum Population Structure and Genetic Diversity Across Multiple Locations and Wheat Varieties in Virginia. PHYTOPATHOLOGY 2024; 114:258-268. [PMID: 37316953 DOI: 10.1094/phyto-10-22-0392-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Parastagonospora nodorum is a necrotrophic pathogen that causes Stagonospora nodorum blotch (SNB) in wheat. Wheat varieties grown in Virginia vary in susceptibility to SNB, and the severity of SNB varies across locations and years. However, the impacts of wheat genetic backgrounds and environments on SNB severity and the structure of P. nodorum populations in the region have not been well studied. Thus, a population genetic study was conducted utilizing P. nodorum isolates collected from different wheat varieties and locations in Virginia. A total of 320 isolates were collected at seven locations over 2 years from five wheat varieties. Isolates were genotyped using multilocus simple sequence repeat markers, and necrotrophic effector (NE) and mating type genes were amplified using gene-specific primers. Wheat varieties varied in susceptibility to SNB, but site-specific environmental conditions were the primary drivers of disease severity. Fungal populations were genetically diverse, but no genetic subdivision was observed among locations or varieties. The ratio of the two mating type idiomorphs was not significantly different from 1:1, consistent with the P. nodorum population undergoing sexual reproduction. Three major NE genes were detected within the P. nodorum population, but not with equal frequency. However, NE gene profiles were similar for groups of isolates originating from different varieties, suggesting that wheat genetic backgrounds do not differentially select for NEs. There was no evidence of population structure among P. nodorum populations in Virginia and, thus, no support for wheat genetic backgrounds shaping these populations. Finally, although varieties only exhibited moderate resistance to SNB, current levels of resistance are likely to be durable over time and remain a useful tool for integrated management of SNB in the region. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Navjot Kaur
- School of Plant and Environmental Sciences, VA Tech, Blacksburg, VA 24061
- Virginia Tech Tidewater Agricultural Research and Extension Center, Suffolk, VA 23437
| | - Hillary L Mehl
- School of Plant and Environmental Sciences, VA Tech, Blacksburg, VA 24061
- Virginia Tech Tidewater Agricultural Research and Extension Center, Suffolk, VA 23437
| | - David Langston
- School of Plant and Environmental Sciences, VA Tech, Blacksburg, VA 24061
- Virginia Tech Tidewater Agricultural Research and Extension Center, Suffolk, VA 23437
| | - David C Haak
- School of Plant and Environmental Sciences, VA Tech, Blacksburg, VA 24061
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Navathe S, He X, Kamble U, Kumar M, Patial M, Singh G, Singh GP, Joshi AK, Singh PK. Assessment of Indian wheat germplasm for Septoria nodorum blotch and tan spot reveals new QTLs conferring resistance along with recessive alleles of Tsn1 and Snn3. FRONTIERS IN PLANT SCIENCE 2023; 14:1223959. [PMID: 37881616 PMCID: PMC10597639 DOI: 10.3389/fpls.2023.1223959] [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: 05/16/2023] [Accepted: 09/20/2023] [Indexed: 10/27/2023]
Abstract
The leaf blight diseases, Septoria nodorum blotch (SNB), and tan spot (TS) are emerging due to changing climatic conditions in the northern parts of India. We screened 296 bread wheat cultivars released in India over the past 20 years for seedling resistance against SNB (three experiments) and TS (two experiments). According to a genome-wide association study, six QTLs on chromosome arms 1BL, 2AS, 5BL, and 6BL were particularly significant for SNB across all three years, of which Q.CIM.snb.1BL, Q.CIM.snb.2AS1, Q.CIM.snb.2AS.2, and Q.CIM.snb.6BL appeared novel. In contrast, those on 5BS and 5BL may correspond to Snn3 and Tsn1, respectively. The allelic combination of tsn1/snn3 conferred resistance to SNB, whereas that of Tsn1/Snn3 conferred high susceptibility. As for TS, Tsn1 was the only stably significant locus identified in this panel. Several varieties like PBW 771, DBW 277, and HD 3319, were identified as highly resistant to both diseases that can be used in future wheat improvement programs as resistant donors.
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Affiliation(s)
- Sudhir Navathe
- Genetics and Plant Breeding Group, Agharkar Research Institute, Pune, India
| | - Xinyao He
- Global Wheat Program, International Maize and Wheat Improvement Centre (CIMMYT), Texcoco, Mexico
| | - Umesh Kamble
- Division of Crop Improvement, ICAR-Indian Institute of Wheat and Barley Research, Karnal, India
| | - Manjeet Kumar
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Madhu Patial
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Gyanendra Singh
- Division of Crop Improvement, ICAR-Indian Institute of Wheat and Barley Research, Karnal, India
| | - Gyanendra Pratap Singh
- Indian Council of Agricultural Research (ICAR)-National Bureau of Plant Genetic Resources, New Delhi, India
| | - Arun Kumar Joshi
- International Maize and Wheat Improvement Centre (CIMMYT) & Borlaug Institute for South Asia (BISA), New Delhi, India
| | - Pawan Kumar Singh
- Global Wheat Program, International Maize and Wheat Improvement Centre (CIMMYT), Texcoco, Mexico
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Chaubey RK, Thakur D, Navathe S, Sharma S, Mishra VK, Singh PK, Chand R. Heterologous expression and characterization of ToxA1 haplotype from India and its interaction with Tsn1 for spot blotch susceptibility in spring wheat. Mol Biol Rep 2023; 50:8213-8224. [PMID: 37561326 DOI: 10.1007/s11033-023-08717-6] [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: 04/15/2023] [Accepted: 07/26/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND ToxA, a necrotrophic effector protein, is present in the genome of fungal species like Parastagnospora nodorum, Pyrenophora tritici-repentis and Bipolaris sorokiniana. Tsn1 is the sensitivity gene in the host whose presence indicates more susceptibility to ToxA carrying pathogen, and ToxA-Tsn1 interaction follows an inverse gene-for-gene relationship. METHODS AND RESULTS The present study involved cloning and expressing the ToxA1 haplotype from B. sorokiniana. It was found that the amplicon exhibited an expected product size of 471 bp. Sequence analysis of the ToxA1 nucleotide sequence revealed the highest identity, 99.79%, with P. tritici-repentis. The protein expression analysis showed peak expression at 16.5 kDa. Phylogenetic analysis of the ToxA1 sequence from all the Bipolaris isolates formed an independent clade along with P. tritici-repentis and diverged from P. nodorum. ToxA-Tsn1 interaction was studied in 18 wheat genotypes (11 Tsn1 and 7 tsn1) at both seedling and adult stages, validating the inverse gene-for-gene relationship, as the toxin activity was highest in the K68 genotype (Tsn1) and lowest in WAMI280 (tsn1). CONCLUSION The study indicates that the haplotype ToxA1 is prevailing in the Indian population of B. sorokiniana. It would be desirable for wheat breeders to select genotypes with tsn1 locus for making wheat resistant to spot blotch.
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Affiliation(s)
- Ranjan Kumar Chaubey
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Dharamsheela Thakur
- Department of Molecular Biology and Genetic Engineering, Bihar Agricultural University, Sabour, Bhagalpur, 813210, India
| | - Sudhir Navathe
- Agharkar Research Institute, G. G. Agarkar Road, Pune, 411004, India.
| | - Sandeep Sharma
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Vinod Kumar Mishra
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Pawan Kumar Singh
- International Maize and Wheat Improvement Center (CIMMYT), 56237, Texcoco, Mexico
| | - Ramesh Chand
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India.
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See PT, Marathamuthu KA, Cupitt CF, Iagallo EM, Moffat CS. A Race Profile of Tan Spot in Australia Reveals Race 2 Isolates Harboring ToxC1. PHYTOPATHOLOGY 2023; 113:1202-1209. [PMID: 36750556 DOI: 10.1094/phyto-11-22-0422-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Tan spot disease is caused by Pyrenophora tritici-repentis (Ptr), one of the major necrotrophic fungal pathogens that affects wheat crops globally. Extensive research has shown that the necrotrophic fungal effectors ToxA, ToxB, and ToxC underlie the genetic interactions of Ptr race classification. ToxA and ToxB are both small proteins secreted during infection; however, the structure of ToxC remains unknown. In line with the recent discovery of the ToxC1 gene that is involved in ToxC production, a subset of 68 isolates collected from the Australian wheat cropping regions were assessed for the presence of all three effectors by pathotyping against four tan spot wheat differential lines and PCR amplification of ToxA, ToxB, and ToxC1. Based on the disease phenotypes, the 68 isolates were grouped into two races with 63 classified as race 1 and five as race 2. A representative selection of each race was tested against eight Australian commercial wheat cultivars and showed no distinction between the virulence levels. Sequencing of ToxA showed that both races had identical gene sequences of haplotype PtrA1. All the race 1 isolates possessed ToxC1 but three race 2 isolates also contained ToxC1 despite being unable to induce a spreading chlorotic symptom on the ToxC differential line. Quantitative trait loci mapping confirmed the absence of the ToxC-Tsc1 association in disease response caused by the ToxC1-containing race 2 isolate; however, ToxC1 expression was detected during plant infection. Altogether, these results suggest that there is a complex regulatory process involved in the production of ToxC within the Australian race 2 isolates.
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Affiliation(s)
- Pao Theen See
- Centre for Crop and Disease Management, Molecular and Life Sciences, School of Science, Curtin University, Bentley, WA 6102, Australia
| | - Kalai A Marathamuthu
- Centre for Crop and Disease Management, Molecular and Life Sciences, School of Science, Curtin University, Bentley, WA 6102, Australia
| | - Catherine F Cupitt
- Centre for Crop and Disease Management, Molecular and Life Sciences, School of Science, Curtin University, Bentley, WA 6102, Australia
| | - Elyce M Iagallo
- Centre for Crop and Disease Management, Molecular and Life Sciences, School of Science, Curtin University, Bentley, WA 6102, Australia
| | - Caroline S Moffat
- Centre for Crop and Disease Management, Molecular and Life Sciences, School of Science, Curtin University, Bentley, WA 6102, Australia
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Aboukhaddour R, Hafez M, McDonald M, Moffat CS, Navathe S, Friesen TL, Strelkov SE, Oliver RP, Tan KC, Liu Z, Moolhuijzen PM, Phan H, See PT, Solomon PS. A Revised Nomenclature for ToxA Haplotypes Across Multiple Fungal Species. PHYTOPATHOLOGY 2023; 113:1180-1184. [PMID: 36809076 DOI: 10.1094/phyto-01-23-0017-sc] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
ToxA is one of the most studied proteinaceous necrotrophic effectors produced by plant pathogens. It has been identified in four pathogens (Pyrenophora tritici-repentis, Parastagonospora nodorum, Parastagonospora pseudonodorum [formerly Parastagonospora avenaria f. sp. tritici], and Bipolaris sorokiniana) causing leaf spot diseases on cereals worldwide. To date, 24 different ToxA haplotypes have been identified. Some P. tritici-repentis and related species also express ToxB, another small protein necrotrophic effector. We present here a revised and standardized nomenclature for these effectors, which could be extended to other poly-haplotypic genes found across multiple species.
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Affiliation(s)
- Reem Aboukhaddour
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada
| | - Mohamed Hafez
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada
| | - Megan McDonald
- School of Biosciences, University of Birmingham, Institute of Microbiology and Infection, Edgbaston, Birmingham, U.K
| | - Caroline S Moffat
- Centre for Crop Disease and Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Sudhir Navathe
- Agharkar Research Institute, Department Science and Technology, Govt. of India, Pune, 411004, India
| | - Timothy L Friesen
- USDA-ARS, Edward T. Schafer Agricultural Research Center, Cereal Crops Research Unit, Fargo, ND 58102-2765, U.S.A
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
| | - Stephen E Strelkov
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | | | - Kar-Chun Tan
- Centre for Crop Disease and Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Zhaohui Liu
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
| | - Paula M Moolhuijzen
- Centre for Crop Disease and Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Huyen Phan
- Centre for Crop Disease and Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Pao Theen See
- Centre for Crop Disease and Management, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Peter S Solomon
- Division of Plant Sciences, Research School of Biology, The Australian National University ACT, Australia
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Malvestiti MC, Steentjes MBF, Beenen HG, Boeren S, van Kan JAL, Shi-Kunne X. Analysis of plant cell death-inducing proteins of the necrotrophic fungal pathogens Botrytis squamosa and Botrytis elliptica. FRONTIERS IN PLANT SCIENCE 2022; 13:993325. [PMID: 36304392 PMCID: PMC9593002 DOI: 10.3389/fpls.2022.993325] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
Fungal plant pathogens secrete proteins that manipulate the host in order to facilitate colonization. Necrotrophs have evolved specialized proteins that actively induce plant cell death by co-opting the programmed cell death machinery of the host. Besides the broad host range pathogen Botrytis cinerea, most other species within the genus Botrytis are restricted to a single host species or a group of closely related hosts. Here, we focused on Botrytis squamosa and B. elliptica, host specific pathogens of onion (Allium cepa) and lily (Lilium spp.), respectively. Despite their occurrence on different hosts, the two fungal species are each other's closest relatives. Therefore, we hypothesize that they share a considerable number of proteins to induce cell death on their respective hosts. In this study, we first confirmed the host-specificity of B. squamosa and B. elliptica. Then we sequenced and assembled high quality genomes. The alignment of these two genomes revealed a high level of synteny with few balanced structural chromosomal arrangements. To assess the cell death-inducing capacity of their secreted proteins, we produced culture filtrates of B. squamosa and B. elliptica that induced cell death responses upon infiltration in host leaves. Protein composition of the culture filtrate was analysed by mass spectrometry, and we identified orthologous proteins that were present in both samples. Subsequently, the expression of the corresponding genes during host infection was compared. RNAseq analysis showed that the majority of the orthogroups of the two sister species display similar expression patterns during infection of their respective host. The analysis of cell death-inducing proteins of B. squamosa and B. elliptica provides insights in the mechanisms used by these two Botrytis species to infect their respective hosts.
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Affiliation(s)
| | | | - Henriek G. Beenen
- Wageningen University, Laboratory of Phytopathology, Wageningen, Netherlands
| | - Sjef Boeren
- Wageningen University, Laboratory of Biochemistry, Wageningen, Netherlands
| | - Jan A. L. van Kan
- Wageningen University, Laboratory of Phytopathology, Wageningen, Netherlands
| | - Xiaoqian Shi-Kunne
- Wageningen University, Laboratory of Phytopathology, Wageningen, Netherlands
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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.
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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
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9
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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.
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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
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10
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Malvestiti MC, Immink RGH, Arens P, Quiroz Monnens T, van Kan JAL. Fire Blight Susceptibility in Lilium spp. Correlates to Sensitivity to Botrytis elliptica Secreted Cell Death Inducing Compounds. FRONTIERS IN PLANT SCIENCE 2021; 12:660337. [PMID: 34262577 PMCID: PMC8273286 DOI: 10.3389/fpls.2021.660337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
Fire blight represents a widespread disease in Lilium spp. and is caused by the necrotrophic Ascomycete Botrytis elliptica. There are >100 Lilium species that fall into distinct phylogenetic groups and these have been used to generate the contemporary commercial genotypes. It is known among lily breeders and growers that different groups of lilies differ in susceptibility to fire blight, but the genetic basis and mechanisms of susceptibility to fire blight are unresolved. The aim of this study was to quantify differences in fire blight susceptibility between plant genotypes and differences in virulence between fungal isolates. To this end we inoculated, in four biological replicates over 2 years, a set of 12 B. elliptica isolates on a panel of 18 lily genotypes representing seven Lilium hybrid groups. A wide spectrum of variation in symptom severity was observed in different isolate-genotype combinations. There was a good correlation between the lesion diameters on leaves and flowers of the Lilium genotypes, although the flowers generally showed faster expanding lesions. It was earlier postulated that B. elliptica pathogenicity on lily is conferred by secreted proteins that induce programmed cell death in lily cells. We selected two aggressive isolates and one mild isolate and collected culture filtrate (CF) samples to compare the cell death inducing activity of their secreted compounds in lily. After leaf infiltration of the CFs, variation was observed in cell death responses between the diverse lilies. The severity of cell death responses upon infiltration of the fungal CF observed among the diverse Lilium hybrid groups correlated well to their fire blight susceptibility. These results support the hypothesis that susceptibility to fire blight in lily is mediated by their sensitivity to B. elliptica effector proteins in a quantitative manner. Cell death-inducing proteins may provide an attractive tool to predict fire blight susceptibility in lily breeding programs.
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Affiliation(s)
- Michele C. Malvestiti
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, Netherlands
| | - Richard G. H. Immink
- Department of Bioscience, Wageningen University & Research, Wageningen, Netherlands
- Laboratory of Molecular Biology, Wageningen University & Research, Wageningen, Netherlands
| | - Paul Arens
- Department of Plant Breeding, Wageningen University & Research, Wageningen, Netherlands
| | - Thomas Quiroz Monnens
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, Netherlands
| | - Jan A. L. van Kan
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, Netherlands
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11
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Downie RC, Lin M, Corsi B, Ficke A, Lillemo M, Oliver RP, Phan HTT, Tan KC, Cockram J. Septoria Nodorum Blotch of Wheat: Disease Management and Resistance Breeding in the Face of Shifting Disease Dynamics and a Changing Environment. PHYTOPATHOLOGY 2021; 111:906-920. [PMID: 33245254 DOI: 10.1094/phyto-07-20-0280-rvw] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The fungus Parastagonospora nodorum is a narrow host range necrotrophic fungal pathogen that causes Septoria nodorum blotch (SNB) of cereals, most notably wheat (Triticum aestivum). Although commonly observed on wheat seedlings, P. nodorum infection has the greatest effect on the adult crop. It results in leaf blotch, which limits photosynthesis and thus crop growth and yield. It can also affect the wheat ear, resulting in glume blotch, which directly affects grain quality. Reports of P. nodorum fungicide resistance, the increasing use of reduced tillage agronomic practices, and high evolutionary potential of the pathogen, combined with changes in climate and agricultural environments, mean that genetic resistance to SNB remains a high priority in many regions of wheat cultivation. In this review, we summarize current information on P. nodorum population structure and its implication for improved SNB management. We then review recent advances in the genetics of host resistance to P. nodorum and the necrotrophic effectors it secretes during infection, integrating the genomic positions of these genetic loci by using the recently released wheat reference genome assembly. Finally, we discuss the genetic and genomic tools now available for SNB resistance breeding and consider future opportunities and challenges in crop health management by using the wheat-P. nodorum interaction as a model.
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Affiliation(s)
- Rowena C Downie
- John Bingham Laboratory, NIAB, Cambridge, CB3 0LE, United Kingdom
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Min Lin
- Norwegian University of Life Sciences, Ås NO-1432, Norway
| | - Beatrice Corsi
- John Bingham Laboratory, NIAB, Cambridge, CB3 0LE, United Kingdom
| | - Andrea Ficke
- Norwegian Institute for Bioeconomy Research, Ås NO-1432, Norway
| | - Morten Lillemo
- Norwegian University of Life Sciences, Ås NO-1432, Norway
| | | | - Huyen T T Phan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley 6102, Perth, WA, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley 6102, Perth, WA, Australia
| | - James Cockram
- John Bingham Laboratory, NIAB, Cambridge, CB3 0LE, United Kingdom
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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.
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Hafez M, Gourlie R, Despins T, Turkington TK, Friesen TL, Aboukhaddour R. Parastagonospora nodorum and Related Species in Western Canada: Genetic Variability and Effector Genes. PHYTOPATHOLOGY 2020; 110:1946-1958. [PMID: 32689900 DOI: 10.1094/phyto-05-20-0207-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Parastagonospora nodorum is an important fungal pathogen that causes Septoria nodorum blotch (SNB) in wheat. This pathogen produces several necrotrophic effectors that act as virulence factors; three have been cloned, SnToxA, SnTox1, and SnTox3. In this study, P. nodorum and its sister species P. avenaria f. tritici (Pat1) were isolated from wheat node and grain samples collected from distanced sites in western Canada during 2018. The presence of effector genes and associated haplotypes were determined by PCR and sequence analysis. An internal transcribed spacer-restriction fragment length polymorphism test was developed to distinguish between leaf spotting pathogens (P. nodorum, Pat1, Pyrenophora tritici-repentis, and Bipolaris sorokiniana). P. nodorum was mainly recovered from wheat nodes and to a lesser extent from the grains, while Pat1 was exclusively isolated from grain samples. The effector genes were present in almost all P. nodorum isolates, with the ToxA haplotype 5 (H5) being most prevalent, while a novel ToxA haplotype (denoted here H21) is reported for the first time. In Pat1, only combinations of SnTox1 and SnTox3 genes were present. A ToxA haplotype network was also constructed to assess the evolutionary relationship among globally found haplotypes to date. Finally, cultivars representing wheat development in Canada for the last century were tested for sensitivity to Sn-effectors and to the presence of Tsn1, the ToxA sensitivity gene. Of tested cultivars, 32.9 and 56.9% were sensitive to SnTox1 and SnTox3, respectively, and Tsn1 was present in 59% of the cultivars. In conclusion, P. nodorum and Pat1 were prevalent wheat pathogens in Canada with a potential tissue-specific colonization capacity, while producing necrotrophic effectors to which wheat is sensitive.
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Affiliation(s)
- Mohamed Hafez
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada (working address)
- Department of Botany and Microbiology, Faculty of Science, Suez University, Suez, Egypt (permanent address)
| | - Ryan Gourlie
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada (working address)
| | - Therese Despins
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada (working address)
| | - Thomas K Turkington
- Agriculture and Agri-Food Canada, Lacombe Research and Development Center, Lacombe, Alberta, Canada
| | - Timothy L Friesen
- U.S. Department of Agriculture, Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND, U.S.A
| | - Reem Aboukhaddour
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Center, Lethbridge, Alberta, Canada (working address)
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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.
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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.
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Phan HTT, Jones DAB, Rybak K, Dodhia KN, Lopez-Ruiz FJ, Valade R, Gout L, Lebrun MH, Brunner PC, Oliver RP, Tan KC. Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction. FRONTIERS IN PLANT SCIENCE 2020; 10:1785. [PMID: 32082346 PMCID: PMC7005668 DOI: 10.3389/fpls.2019.01785] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 12/20/2019] [Indexed: 05/30/2023]
Abstract
INTRODUCTION Septoria nodorum blotch (SNB) is a complex fungal disease of wheat caused by the Dothideomycete fungal pathogen Parastagonospora nodorum. The fungus infects through the use of necrotrophic effectors (NEs) that cause necrosis on hosts carrying matching dominant susceptibility genes. The Western Australia (WA) wheatbelt is a SNB "hot spot" and experiences significant under favorable conditions. Consequently, SNB has been a major target for breeders in WA for many years. MATERIALS AND METHODS In this study, we assembled a panel of 155 WA P. nodorum isolates collected over a 44-year period and compared them to 23 isolates from France and the USA using 28 SSR loci. RESULTS The WA P. nodorum population was clustered into five groups with contrasting properties. 80% of the studied isolates were assigned to two core groups found throughout the collection location and time. The other three non-core groups that encompassed transient and emergent populations were found in restricted locations and time. Changes in group genotypes occurred during periods that coincided with the mass adoption of a single or a small group of widely planted wheat cultivars. When introduced, these cultivars had high scores for SNB resistance. However, the field resistance of these new cultivars often declined over subsequent seasons prompting their replacement with new, more resistant varieties. Pathogenicity assays showed that newly emerged isolates non-core are more pathogenic than old isolates. It is likely that the non-core groups were repeatedly selected for increased virulence on the contemporary popular cultivars. DISCUSSION The low level of genetic diversity within the non-core groups, difference in virulence, low abundance, and restriction to limited locations suggest that these populations more vulnerable to a population crash when the cultivar was replaced by one that was genetically different and more resistant. We characterize the observed pattern as a low-amplitude boom-and-bust cycle in contrast with the classical high amplitude boom-and-bust cycles seen for biotrophic pathogens where the contrast between resistance and susceptibility is typically much greater. Implications of the results are discussed relating to breeding strategies for more sustainable SNB resistance and more generally for pathogens with NEs.
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Affiliation(s)
- Huyen T. T. Phan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Darcy A. B. Jones
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kasia Rybak
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kejal N. Dodhia
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Francisco J. Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Romain Valade
- ARVALIS Institut du Végétal Avenue Lucien Brétignières, Bâtiment INRA Bioger, Thiverval-Grignon, France
| | - Lilian Gout
- UMR INRA Bioger Agro-ParisTech, Thiverval-Grignon, France
| | | | - Patrick C. Brunner
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Richard P. Oliver
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
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Navathe S, Yadav PS, Chand R, Mishra VK, Vasistha NK, Meher PK, Joshi AK, Gupta PK. ToxA- Tsn1 Interaction for Spot Blotch Susceptibility in Indian Wheat: An Example of Inverse Gene-for-Gene Relationship. PLANT DISEASE 2020; 104:71-81. [PMID: 31697221 DOI: 10.1094/pdis-05-19-1066-re] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The ToxA-Tsn1 system is an example of an inverse gene-for-gene relationship. The gene ToxA encodes a host-selective toxin (HST) which functions as a necrotrophic effector and is often responsible for the virulence of the pathogen. The genomes of several fungal pathogens (e.g., Pyrenophora tritici-repentis, Parastagonospora nodorum, and Bipolaris sorokiniana) have been shown to carry the ToxA gene. Tsn1 is a sensitivity gene in the host, whose presence generally helps a ToxA-positive pathogen to cause spot blotch in wheat. Cultivars lacking Tsn1 are generally resistant to spot blotch; this resistance is attributed to a number of other known genes which impart resistance in the absence of Tsn1. In the present study, 110 isolates of B. sorokiniana strains, collected from the ME5A and ME4C megaenvironments of India, were screened for the presence of the ToxA gene; 77 (70%) were found to be ToxA positive. Similarly, 220 Indian wheat cultivars were screened for the presence of the Tsn1 gene; 81 (36.8%) were found to be Tsn1 positive. When 20 wheat cultivars (11 with Tsn1 and 9 with tsn1) were inoculated with ToxA-positive isolates, seedlings of only those carrying the Tsn1 allele (not tsn1) developed necrotic spots surrounded by a chlorotic halo. No such distinction between Tsn1 and tsn1 carriers was observed when adult plants were inoculated. This study suggests that the absence of Tsn1 facilitated resistance against spot blotch of wheat. Therefore, the selection of wheat genotypes for the absence of the Tsn1 allele can improve resistance to spot blotch.
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Affiliation(s)
- Sudhir Navathe
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Punam Singh Yadav
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Ramesh Chand
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Vinod Kumar Mishra
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Neeraj Kumar Vasistha
- Molecular Biology Laboratory, Department of Genetics and Plant Breeding, Ch. Charan Singh University, Meerut, 250004, India
| | - Prabina Kumar Meher
- Division of Statistical Genetics, ICAR-Indian Agricultural Statistical Research Institute, Pusa, New Delhi, 110012, India
| | - Arun Kumar Joshi
- International Maize and Wheat Improvement Center (CIMMYT), G-2, B-Block, NASC Complex, DPS Marg, New Delhi, 110012, India
- Borlaug Institute for South Asia (BISA), G-2, B-Block, NASC Complex, DPS Marg, New Delhi, 110012, India
| | - Pushpendra Kumar Gupta
- Molecular Biology Laboratory, Department of Genetics and Plant Breeding, Ch. Charan Singh University, Meerut, 250004, India
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17
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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: 25] [Impact Index Per Article: 5.0] [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.
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18
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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]
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19
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See PT, Iagallo EM, Oliver RP, Moffat CS. Heterologous Expression of the Pyrenophora tritici-repentis Effector Proteins ToxA and ToxB, and the Prevalence of Effector Sensitivity in Australian Cereal Crops. Front Microbiol 2019; 10:182. [PMID: 30809209 PMCID: PMC6379657 DOI: 10.3389/fmicb.2019.00182] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/23/2019] [Indexed: 12/05/2022] Open
Abstract
Here, we evaluate the expression of the proteinaceous effectors ToxA and ToxB, produced by the necrotrophic fungal pathogen Pyrenophora tritici-repentis, which confer tan spot disease susceptibility on wheat. These necrotrophic effectors were expressed in two heterologous systems: Escherichia coli and Pichia pastoris. The E. coli SHuffle system was demonstrated to be superior to P. pastoris in generating high-levels of recombinant proteins that were soluble and stable. In addition, protein extracts from P. pastoris induced non-specific chlorosis on wheat, postulated to be caused by co-purified glucanases secreted by the host. Up to 79.6 μg/ml of ToxB was obtained using the SHuffle system in the absence of the native signal peptide, whilst the ToxA yield was considerably lower at 3.2 μg/ml. Results indicated that a histidine tag at the ToxA C-terminus interfered with effector functionality. Heterologously expressed ToxA and ToxB were tested on a panel of Australian cereals, including 122 varieties of bread wheat, 16 durum, 20 triticale and 5 barley varieties, as well as common plant model species including tobacco and Arabidopsis thaliana. A varying degree of effector sensitivities was observed, with a higher ToxB sensitivity and prevalence in the durum and triticale varieties. ToxB-induced chlorosis was also detected on barley. The heterologous expression of effectors that are easily scalable, will facilitate effector-assisted selection of varieties in wheat breeding programs as well as the investigation of P. tritici-repentis effectors in host and non-host interactions.
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Affiliation(s)
| | | | | | - Caroline S. Moffat
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
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20
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Moolhuijzen PM, See PT, Oliver RP, Moffat CS. Genomic distribution of a novel Pyrenophora tritici-repentis ToxA insertion element. PLoS One 2018; 13:e0206586. [PMID: 30379913 PMCID: PMC6209302 DOI: 10.1371/journal.pone.0206586] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 10/16/2018] [Indexed: 12/12/2022] Open
Abstract
The ToxA effector is a major virulence gene of Pyrenophora tritici-repentis (Ptr), a necrotrophic fungus and the causal agent of tan spot disease of wheat. ToxA and co-located genes are believed to be the result of a recent horizontally transferred highly conserved 14kb region a major pathogenic event for Ptr. Since this event, monitoring isolates for pathogenic changes has become important to help understand the underlying mechanisms in play. Here we examined ToxA in 100 Ptr isolates from Australia, Europe, North and South America and the Middle East, and uncovered in isolates from Denmark, Germany and New Zealand a new variation, a novel 166 bp insertion element (PtrHp1) which can form a perfectly matched 59 bp inverted repeat hairpin structure located downstream of the ToxA coding sequence in the 3’ UTR exon. A wider examination revealed PtrHp1 elements to be distributed throughout the genome. Analysis of genomes from Australia and North America had 50–112 perfect copies that often overlap other genes. The hairpin element appears to be unique to Ptr and the lack of ancient origins in other species suggests that PtrHp1 emerged after Ptr speciation. Furthermore, the ToxA UTR insertion site is identical for different isolates, which suggests a single insertion event occurred after the ToxA horizontal transfer. In vitro and in planta-detached leaf assays found that the PtrHp1 element insertion had no effect on ToxA expression. However, variation in the expression of ToxA was detected between the Ptr isolates from different demographic locations, which appears to be unrelated to the presence of the element. We envision that this discovery may contribute towards future understanding of the possible role of hairpin elements in Ptr.
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Affiliation(s)
- Paula M Moolhuijzen
- Centre for Crop Disease and Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
| | - Pao Theen See
- Centre for Crop Disease and Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
| | - Richard P Oliver
- Centre for Crop Disease and Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
| | - Caroline S Moffat
- Centre for Crop Disease and Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
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21
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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.
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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.
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Downie RC, Bouvet L, Furuki E, Gosman N, Gardner KA, Mackay IJ, Campos Mantello C, Mellers G, Phan HTT, Rose GA, Tan KC, Oliver RP, Cockram J. Assessing European Wheat Sensitivities to Parastagonospora nodorum Necrotrophic Effectors and Fine-Mapping the Snn3-B1 Locus Conferring Sensitivity to the Effector SnTox3. FRONTIERS IN PLANT SCIENCE 2018. [PMID: 30022985 DOI: 10.3389/fpls.2017.0881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Parastagonospora nodorum is a necrotrophic fungal pathogen of wheat (Triticum aestivum L.), one of the world's most important crops. P. nodorum mediates host cell death using proteinaceous necrotrophic effectors, presumably liberating nutrients that allow the infection process to continue. The identification of pathogen effectors has allowed host genetic resistance mechanisms to be separated into their constituent parts. In P. nodorum, three proteinaceous effectors have been cloned: SnToxA, SnTox1, and SnTox3. Here, we survey sensitivity to all three effectors in a panel of 480 European wheat varieties, and fine-map the wheat SnTox3 sensitivity locus Snn3-B1 using genome-wide association scans (GWAS) and an eight-founder wheat multi-parent advanced generation inter-cross (MAGIC) population. Using a Bonferroni corrected P ≤ 0.05 significance threshold, GWAS identified 10 significant markers defining a single locus, Snn3-B1, located on the short arm of chromosome 5B explaining 32% of the phenotypic variation [peak single nucleotide polymorphisms (SNPs), Excalibur_c47452_183 and GENE-3324_338, -log10P = 20.44]. Single marker analysis of SnTox3 sensitivity in the MAGIC population located Snn3-B1 via five significant SNPs, defining a 6.2-kb region that included the two peak SNPs identified in the association mapping panel. Accordingly, SNP Excalibur_c47452_183 was converted to the KASP genotyping system, and validated by screening a subset of 95 wheat varieties, providing a valuable resource for marker assisted breeding and for further genetic investigation. In addition, composite interval mapping in the MAGIC population identified six minor SnTox3 sensitivity quantitative trait loci, on chromosomes 2A (QTox3.niab-2A.1, P-value = 9.17-7), 2B (QTox3.niab-2B.1, P = 0.018), 3B (QTox3.niab-3B.1, P = 48.51-4), 4D (QTox3.niab-4D.1, P = 0.028), 6A (QTox3.niab-6A.1, P = 8.51-4), and 7B (QTox3.niab-7B.1, P = 0.020), each accounting for between 3.1 and 6.0 % of the phenotypic variance. Collectively, the outcomes of this study provides breeders with knowledge and resources regarding the sensitivity of European wheat germplasm to P. nodorum effectors, as well as simple diagnostic markers for determining allelic state at Snn3-B1.
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Affiliation(s)
- Rowena C Downie
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
- Plant Sciences Department, University of Cambridge, Cambridge, United Kingdom
| | - Laura Bouvet
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
- Plant Sciences Department, University of Cambridge, Cambridge, United Kingdom
| | - Eiko Furuki
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Nick Gosman
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Keith A Gardner
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Ian J Mackay
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Camila Campos Mantello
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Greg Mellers
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Huyen T T Phan
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Gemma A Rose
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Richard P Oliver
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - James Cockram
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
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23
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Downie RC, Bouvet L, Furuki E, Gosman N, Gardner KA, Mackay IJ, Campos Mantello C, Mellers G, Phan HTT, Rose GA, Tan KC, Oliver RP, Cockram J. Assessing European Wheat Sensitivities to Parastagonospora nodorum Necrotrophic Effectors and Fine-Mapping the Snn3-B1 Locus Conferring Sensitivity to the Effector SnTox3. FRONTIERS IN PLANT SCIENCE 2018; 9:881. [PMID: 30022985 PMCID: PMC6039772 DOI: 10.3389/fpls.2018.00881] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/06/2018] [Indexed: 05/18/2023]
Abstract
Parastagonospora nodorum is a necrotrophic fungal pathogen of wheat (Triticum aestivum L.), one of the world's most important crops. P. nodorum mediates host cell death using proteinaceous necrotrophic effectors, presumably liberating nutrients that allow the infection process to continue. The identification of pathogen effectors has allowed host genetic resistance mechanisms to be separated into their constituent parts. In P. nodorum, three proteinaceous effectors have been cloned: SnToxA, SnTox1, and SnTox3. Here, we survey sensitivity to all three effectors in a panel of 480 European wheat varieties, and fine-map the wheat SnTox3 sensitivity locus Snn3-B1 using genome-wide association scans (GWAS) and an eight-founder wheat multi-parent advanced generation inter-cross (MAGIC) population. Using a Bonferroni corrected P ≤ 0.05 significance threshold, GWAS identified 10 significant markers defining a single locus, Snn3-B1, located on the short arm of chromosome 5B explaining 32% of the phenotypic variation [peak single nucleotide polymorphisms (SNPs), Excalibur_c47452_183 and GENE-3324_338, -log10P = 20.44]. Single marker analysis of SnTox3 sensitivity in the MAGIC population located Snn3-B1 via five significant SNPs, defining a 6.2-kb region that included the two peak SNPs identified in the association mapping panel. Accordingly, SNP Excalibur_c47452_183 was converted to the KASP genotyping system, and validated by screening a subset of 95 wheat varieties, providing a valuable resource for marker assisted breeding and for further genetic investigation. In addition, composite interval mapping in the MAGIC population identified six minor SnTox3 sensitivity quantitative trait loci, on chromosomes 2A (QTox3.niab-2A.1, P-value = 9.17-7), 2B (QTox3.niab-2B.1, P = 0.018), 3B (QTox3.niab-3B.1, P = 48.51-4), 4D (QTox3.niab-4D.1, P = 0.028), 6A (QTox3.niab-6A.1, P = 8.51-4), and 7B (QTox3.niab-7B.1, P = 0.020), each accounting for between 3.1 and 6.0 % of the phenotypic variance. Collectively, the outcomes of this study provides breeders with knowledge and resources regarding the sensitivity of European wheat germplasm to P. nodorum effectors, as well as simple diagnostic markers for determining allelic state at Snn3-B1.
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Affiliation(s)
- Rowena C. Downie
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
- Plant Sciences Department, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Rowena C. Downie, James Cockram,
| | - Laura Bouvet
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
- Plant Sciences Department, University of Cambridge, Cambridge, United Kingdom
| | - Eiko Furuki
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Nick Gosman
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Keith A. Gardner
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Ian J. Mackay
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Camila Campos Mantello
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Greg Mellers
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Huyen T. T. Phan
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Gemma A. Rose
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - Richard P. Oliver
- Centre for Crop and Disease Management, Curtin University, Perth, WA, Australia
| | - James Cockram
- Genetics and Breeding Department, National Institute of Agricultural Botany, Cambridge, United Kingdom
- *Correspondence: Rowena C. Downie, James Cockram,
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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.
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25
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Ruud AK, Windju S, Belova T, Friesen TL, Lillemo M. Mapping of SnTox3-Snn3 as a major determinant of field susceptibility to Septoria nodorum leaf blotch in the SHA3/CBRD × Naxos population. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2017; 130:1361-1374. [PMID: 28365817 DOI: 10.1007/s00122-017-2893-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/18/2017] [Indexed: 05/03/2023]
Abstract
The effect of the SnTox3-Snn3 interaction was documented for the first time under natural infection at the adult plant stage in the field. Co-segregating SNP markers were identified. Parastagonospora nodorum is a necrotrophic pathogen of wheat, causing Septoria nodorum blotch (SNB) affecting both the leaf and glume. P. nodorum is the major leaf blotch pathogen on spring wheat in Norway. Resistance to the disease is quantitative, but several host-specific interactions between necrotrophic effectors (NEs) and host sensitivity (Snn) genes have been identified, playing a major role at the seedling stage. However, the effect of these interactions in the field under natural infection has not been investigated. In the present study, we saturated the genetic map of the recombinant inbred (RI) population SHA3/CBRD × Naxos using the Illumina 90 K SNP chip. The population had previously been evaluated for segregation of SNB susceptibility in field trials. Here, we infiltrated the population with the purified NEs SnToxA, SnTox1 and SnTox3, and mapped the Snn3 locus on 5BS based on sensitivity segregation and SNP marker data. We also conducted inoculation and culture filtrate (CF) infiltration experiments on the population with four selected P. nodorum isolates from Norway and North America. Remapping of quantitative trait loci (QTL) for field resistance showed that the SnTox3-Snn3 interaction could explain 24% of the phenotypic variation in the field, and more than 51% of the variation in seedling inoculations. To our knowledge, this is the first time the effect of this interaction has been documented at the adult plant stage under natural infection in the field.
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Affiliation(s)
- Anja Karine Ruud
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway
| | - Susanne Windju
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway
- Graminor AS, Bjørke Gård, Hommelstadvegen 60, 2322, Ridabu, Norway
| | - Tatiana Belova
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway
| | - Timothy L Friesen
- Northern Crop Science Laboratory, USDA-ARS, 1307 North 18th Street, Fargo, ND, 58102, USA
- Department of Plant Pathology, North Dakota State University, Walster Hall, Fargo, ND, 58102, USA
| | - Morten Lillemo
- Department of Plant Sciences, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway.
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26
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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: 49] [Impact Index Per Article: 7.0] [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.
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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
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27
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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.
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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.
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28
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Shi G, Zhang Z, Friesen TL, Bansal U, Cloutier S, Wicker T, Rasmussen JB, Faris JD. Marker development, saturation mapping, and high-resolution mapping of the Septoria nodorum blotch susceptibility gene Snn3-B1 in wheat. Mol Genet Genomics 2015; 291:107-19. [PMID: 26187026 DOI: 10.1007/s00438-015-1091-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 07/01/2015] [Indexed: 12/29/2022]
Abstract
Septoria nodorum blotch (SNB), caused by Parastagonospora nodorum, is a severe foliar and glume disease on durum and common wheat. Pathogen-produced necrotrophic effectors (NEs) are the major determinants for SNB on leaves. One such NE is SnTox3, which evokes programmed cell death and leads to disease when recognized by the wheat Snn3-B1 gene. Here, we developed saturated genetic linkage maps of the Snn3-B1 region using two F2 populations derived from the SnTox3-sensitive line Sumai 3 crossed with different SnTox3-insensitive lines. Markers were identified and/or developed from various resources including previously mapped simple sequence repeats, bin-mapped expressed sequence tags, single nucleotide polymorphisms, and whole genome survey sequences. Subsequent high-resolution mapping of the Snn3-B1 locus in 5600 gametes delineated the gene to a 1.5 cM interval. Analysis of micro-colinearity of the Snn3-B1 region indicated that it was highly disrupted compared to rice and Brachypodium distachyon. The screening of a collection of durum and common wheat cultivars with tightly linked markers indicated they are not diagnostic for the presence of Snn3-B1, but can be useful for marker-assisted selection if the SnTox3 reactions of lines are first determined. Finally, we developed an ethyl methanesulfonate-induced mutant population of Sumai 3 where the screening of 408 M2 families led to the identification of 17 SnTox3-insensitive mutants. These mutants along with the markers and high-resolution map developed in this research provide a strong foundation for the map-based cloning of Snn3-B1, which will broaden our understanding of the wheat-P. nodorum system and plant-necrotrophic pathogen interactions in general.
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Affiliation(s)
- Gongjun Shi
- Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA
| | - Zengcui Zhang
- USDA-ARS Cereal Crops Research Unit, USDA-ARS NPA NCSL, Red River Valley Agricultural Research Center, 1605 Albrecht BLVD, Fargo, ND, 58102-2765, USA
| | - Timothy L Friesen
- USDA-ARS Cereal Crops Research Unit, USDA-ARS NPA NCSL, Red River Valley Agricultural Research Center, 1605 Albrecht BLVD, Fargo, ND, 58102-2765, USA
| | - Urmil Bansal
- The University of Sydney PBI-Cobbity, Private Bag 4011, Narellan, NSW, 2567, Australia
| | - Sylvie Cloutier
- Eastern Cereal and Oil Research Centre, Agriculture and Agri-Food Canada, K.W. Neatby Building, 960 Carling Avenue, Ottawa, ON, K1A 0C6, Canada
| | - Thomas Wicker
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - Jack B Rasmussen
- Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA
| | - Justin D Faris
- USDA-ARS Cereal Crops Research Unit, USDA-ARS NPA NCSL, Red River Valley Agricultural Research Center, 1605 Albrecht BLVD, Fargo, ND, 58102-2765, USA.
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29
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Lu S, Gillian Turgeon B, Edwards MC. A ToxA-like protein from Cochliobolus heterostrophus induces light-dependent leaf necrosis and acts as a virulence factor with host selectivity on maize. Fungal Genet Biol 2015; 81:12-24. [PMID: 26051492 DOI: 10.1016/j.fgb.2015.05.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/28/2015] [Accepted: 05/29/2015] [Indexed: 11/30/2022]
Abstract
ToxA, the first discovered fungal proteinaceous host-selective toxin (HST), was originally identified in 1989 from the tan spot fungus Pyrenophora tritici-repentis (Ptr). About 25years later, a homolog was identified in the leaf/glume blotch fungus Stagonospora nodorum (Parastagonospora nodorum), also a pathogen of wheat. Here we report the identification and function of a ToxA-like protein from the maize pathogen Cochliobolus heterostrophus (Ch) that possesses necrosis-inducing activity specifically against maize. ChToxA is encoded by a 535-bp open reading frame featuring a ToxA-specific intron with unusual splicing sites (5'-ATAAGT…TAC-3') at conserved positions relative to PtrToxA. The protein shows 64% similarity to PtrToxA and is predicted to adopt a similar three-dimensional structure, although lacking the arginyl-glycyl-aspartic acid (RGD) motif reported to be required for internalization into sensitive wheat mesophyll cells. Reverse-transcriptase PCR revealed that the ChTOXA gene expression is up-regulated in planta, relative to axenic culture. Plant assays indicated that the recombinant ChToxA protein induces light-dependent leaf necrosis in a host-selective manner on maize inbred lines. Gene deletion experiments confirmed that ChtoxA mutants are reduced in virulence on specific ChToxA-sensitive maize lines, relative to virulence caused by wild-type strains. Database searches identified potential ChToxA homologues in other plant-pathogenic ascomycetes. Sequence and phylogenetic analyses revealed that the corresponding ToxA-like proteins include one member recently shown to be associated with formation of penetration hypha. These results provide the first evidence that C. heterostrophus is capable of producing proteinaceous HSTs as virulence factors in addition to well-known secondary metabolite-type toxins produced biosynthetically by polyketide synthase megaenzymes. Further studies on ChToxA may provide new insights into effector evolution in host-pathogen interactions.
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Affiliation(s)
- Shunwen Lu
- US Department of Agriculture, Agricultural Research Service, Cereal Crops Research Unit, Fargo, ND 58102-2765, USA.
| | - B Gillian Turgeon
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Michael C Edwards
- US Department of Agriculture, Agricultural Research Service, Cereal Crops Research Unit, Fargo, ND 58102-2765, USA
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30
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Tan KC, Phan HTT, Rybak K, John E, Chooi YH, Solomon PS, Oliver RP. Functional redundancy of necrotrophic effectors - consequences for exploitation for breeding. FRONTIERS IN PLANT SCIENCE 2015; 6:501. [PMID: 26217355 PMCID: PMC4495316 DOI: 10.3389/fpls.2015.00501] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Necrotrophic diseases of wheat cause major losses in most wheat growing areas of world. Tan spot (caused by Pyrenophora tritici-repentis) and septoria nodorum blotch (SNB; Parastagonospora nodorum) have been shown to reduce yields by 10-20% across entire agri-ecological zones despite the application of fungicides and a heavy focus over the last 30 years on resistance breeding. Efforts by breeders to improve the resistance of cultivars has been compromised by the universal finding that resistance was quantitative and governed by multiple quantitative trait loci (QTL). Most QTL had a limited effect that was hard to measure precisely and varied significantly from site to site and season to season. The discovery of necrotrophic effectors has given breeding for disease resistance new methods and tools. In the case of tan spot in West Australia, a single effector, PtrToxA and its recogniser gene Tsn1, has a dominating impact in disease resistance. The delivery of ToxA to breeders has had a major impact on cultivar choice and breeding strategies. For P. nodorum, three effectors - SnToxA, SnTox1, and SnTox3 - have been well characterized. Unlike tan spot, no one effector has a dominating role. Genetic analysis of various mapping populations and pathogen isolates has shown that different effectors have varying impact and that epistatic interactions also occur. As a result of these factors the deployment of these effectors for SNB resistance breeding is more complex. We have deleted the three effectors in a strain of P. nodorum and measured effector activity and disease potential of the triple knockout mutant. The culture filtrate causes necrosis in several cultivars and the strain causes disease, albeit the overall levels are less than in the wild type. Modeling of the field disease resistance scores of cultivars from their reactions to the microbially expressed effectors SnToxA, SnTox1, and SnTox3 is significantly improved by including the response to the triple knockout mutant culture filtrate. This indicates that one or more further effectors are secreted into the culture filtrate. We conclude that the in vitro-secreted necrotrophic effectors explain a very large part of the disease response of wheat germplasm and that this method of resistance breeding promises to further reduce the impact of these globally significant diseases.
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Affiliation(s)
- Kar-Chun Tan
- Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, BentleyWA, Australia
- *Correspondence: Richard P. Oliver and Kar-Chun Tan, Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA 6102, Australia, ;
| | - Huyen T. T. Phan
- Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, BentleyWA, Australia
| | - Kasia Rybak
- Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, BentleyWA, Australia
| | - Evan John
- Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, BentleyWA, Australia
| | - Yit H. Chooi
- Plant Sciences Division, Research School of Biology, Australian National University, CanberraACT, Australia
- School of Chemistry and Biochemistry, University of Western Australia, PerthWA, Australia
| | - Peter S. Solomon
- Plant Sciences Division, Research School of Biology, Australian National University, CanberraACT, Australia
| | - Richard P. Oliver
- Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, BentleyWA, Australia
- *Correspondence: Richard P. Oliver and Kar-Chun Tan, Centre for Crop Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA 6102, Australia, ;
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31
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Moffat CS, See PT, Oliver RP. Generation of a ToxA knockout strain of the wheat tan spot pathogen Pyrenophora tritici-repentis. MOLECULAR PLANT PATHOLOGY 2014; 15:918-26. [PMID: 24831982 PMCID: PMC6638721 DOI: 10.1111/mpp.12154] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The necrotrophic fungal pathogen Pyrenophora tritici-repentis causes tan spot, a major disease of wheat, throughout the world. The proteinaceous effector ToxA is responsible for foliar necrosis on ToxA-sensitive wheat genotypes. The single copy ToxA gene was deleted from a wild-type race 1 P. tritici-repentis isolate via homologous recombination of a knockout construct. Expression of the ToxA transcript was found to be absent in transformants (toxa), as was ToxA protein production in fungal culture filtrates. Plant bioassays were conducted to test transformant pathogenicity. The toxa strains were unable to induce necrosis on ToxA-sensitive wheat genotypes. To our knowledge, this is the first demonstration of a targeted gene knockout in P. tritici-repentis. The ability to undertake gene deletions will facilitate the characterization of other pathogenicity effectors of this economically significant necrotroph.
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Affiliation(s)
- Caroline S Moffat
- Centre for Crop and Disease Management, Department of Environment and Agriculture, School of Science, Curtin University, Perth, WA, 6102, Australia
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Lu S, Faris JD, Sherwood R, Friesen TL, Edwards MC. A dimeric PR-1-type pathogenesis-related protein interacts with ToxA and potentially mediates ToxA-induced necrosis in sensitive wheat. MOLECULAR PLANT PATHOLOGY 2014; 15:650-63. [PMID: 24433289 PMCID: PMC6638811 DOI: 10.1111/mpp.12122] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A dimeric PR-1-type pathogenesis-related protein (PR-1-5), recently identified in wheat, was found to interact with Stagonospora nodorum ToxA in both yeast two-hybrid and co-immunoprecipitation assays. Site-specific mutational analyses revealed that the RGD motif of ToxA is not targeted by PR-1-5, whereas two surface-exposed asparagine residues are essential for the interaction: the N102 residue of the turning loop between β2 and β3 in ToxA and the N141 residue of the turning loop between βC and βD in PR-1-5. Recombinant PR-1-5 and ToxA mutant proteins carrying alanine substitutions at the interacting sites were expressed in Pichia pastoris, together with the wild-type proteins. Native polyacrylamide gel electrophoresis (PAGE) confirmed that the PR-1-5-N141A mutant retains the ability to form dimers. Plant assays indicated that the ToxA-N102A mutant fails to induce necrosis, whereas the PR-1-5-N141A mutant is impaired in the 'necrosis-promoting' activity shown by the wild-type PR-1-5 when co-infiltrated with ToxA in sensitive wheat. Reverse transcriptase-polymerase chain reaction and Western blot analyses revealed that the native PR-1-5 protein is differentially expressed between ToxA-sensitive and ToxA-insensitive wheat lines in response to ToxA treatment. These results suggest that PR-1-5 is a potential target of ToxA and the site-specific interaction between PR-1-5 and ToxA may mediate ToxA-induced necrosis in sensitive wheat.
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Affiliation(s)
- Shunwen Lu
- Cereal Crops Research Unit, USDA-ARS, Fargo, ND, 58102, USA
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Stotz HU, Mitrousia GK, de Wit PJGM, Fitt BDL. Effector-triggered defence against apoplastic fungal pathogens. TRENDS IN PLANT SCIENCE 2014; 19:491-500. [PMID: 24856287 PMCID: PMC4123193 DOI: 10.1016/j.tplants.2014.04.009] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 04/07/2014] [Accepted: 04/23/2014] [Indexed: 05/18/2023]
Abstract
R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed 'effector-triggered defence' (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops.
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Affiliation(s)
- Henrik U Stotz
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | - Georgia K Mitrousia
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | - Pierre J G M de Wit
- Wageningen University and Research Centre, Laboratory of Phytopathology, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Bruce D L Fitt
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, AL10 9AB, UK.
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Bertucci M, Brown-Guedira G, Murphy JP, Cowger C. Genes Conferring Sensitivity to Stagonospora nodorum Necrotrophic Effectors in Stagonospora Nodorum Blotch-Susceptible U.S. Wheat Cultivars. PLANT DISEASE 2014; 98:746-753. [PMID: 30708627 DOI: 10.1094/pdis-08-13-0820-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Stagonospora nodorum is a necrotrophic fungal pathogen that causes Stagonospora nodorum blotch (SNB), a yield- and quality-reducing disease of wheat. S. nodorum produces a set of necrotrophic effectors (NEs) that interact with the products of host sensitivity genes to cause cell death and increased susceptibility to disease. The focus of this study was determination of NE sensitivity among 25 winter wheat cultivars, many of them from the southeastern United States, that are susceptible to SNB, as well as the moderately resistant 'NC-Neuse'. Thirty-three isolates of S. nodorum previously collected from seven southeastern U.S. states were cultured for NE production, and the culture filtrates were used in an infiltration bioassay. Control strains of Pichia pastoris that expressed SnToxA, SnTox1, or SnTox3 were also used. All SNB-susceptible cultivars were sensitive to at least one NE, while NC-Neuse was insensitive to all NEs tested. Among the sensitive lines, 32% contained sensitivity gene Tsn1 and 64% contained sensitivity gene Snn3. None were sensitive to SnTox1. Additionally, 10 molecular markers for sensitivity genes Tsn1, Snn1, Snn2, and Snn3 were evaluated for diagnostic potential. Only the marker Xfcp623 for Tsn1 was diagnostic, and it was in perfect agreement with the results of the infiltration bioassays. The results illuminate which NE sensitivity genes may be of concern in breeding for resistance to SNB in the southeastern United States.
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Affiliation(s)
- Matthew Bertucci
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Department of Plant Pathology, North Carolina State University, Raleigh 27695
| | - Gina Brown-Guedira
- Department of Crop Science, North Carolina State University, Raleigh 27695
| | - J Paul Murphy
- USDA-ARS, Department of Crop Science, North Carolina State University, Raleigh 27606
| | - Christina Cowger
- USDA-ARS, Department of Plant Pathology, North Carolina State University, Raleigh 27695
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McDonald MC, Oliver RP, Friesen TL, Brunner PC, McDonald BA. Global diversity and distribution of three necrotrophic effectors in Phaeosphaeria nodorum and related species. THE NEW PHYTOLOGIST 2013; 199:241-251. [PMID: 23550706 DOI: 10.1111/nph.12257] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 02/22/2013] [Indexed: 05/07/2023]
Abstract
Population genetic and phylogenetic studies have shown that Phaeosphaeria nodorum is a member of a species complex that probably shares its center of origin with wheat (Triticum aestivum and Triticum durum). We examined the evolutionary histories of three known necrotrophic effectors (NEs) produced by P. nodorum and compared them with neutral loci. We screened over 1000 individuals for the presence/absence of each effector and assigned each individual to a multi-effector genotype. Diversity at each NE locus was assessed by sequencing c. 200 individuals for each locus. We found significant differences in effector frequency among populations. We propose that these differences reflect the presence/absence of the corresponding susceptibility gene in wheat cultivars. The population harboring the highest sequence diversity was different for each effector locus and never coincided with populations harboring the highest diversity at neutral loci. Coalescent and phylogenetic analyses showed a discontinuous presence of all three NEs among nine closely related Phaeosphaeria species. Only two of the nine species were found to harbor NEs. We present evidence that the three described NEs of P. nodorum were transmitted to its sister species, Phaeosphaeria avenaria tritici 1, via interspecific hybridization.
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Affiliation(s)
- Megan C McDonald
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Richard P Oliver
- Australian Centre for Necrotrophic Fungal Pathogens, Department of Environment and Agriculture, Curtin University, Perth, WA, 6845, Australia
| | - Timothy L Friesen
- United States Department of Agriculture-Agriculture Research Service, Northern Crop Science Laboratory, Cereal Crops Research Unit, Fargo, ND, 58105, USA
| | - Patrick C Brunner
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, CH-8092, Zurich, Switzerland
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Resequencing and comparative genomics of Stagonospora nodorum: sectional gene absence and effector discovery. G3-GENES GENOMES GENETICS 2013; 3:959-69. [PMID: 23589517 PMCID: PMC3689807 DOI: 10.1534/g3.112.004994] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Stagonospora nodorum is an important wheat (Triticum aestivum) pathogen in many parts of the world, causing major yield losses. It was the first species in the large fungal Dothideomycete class to be genome sequenced. The reference genome sequence (SN15) has been instrumental in the discovery of genes encoding necrotrophic effectors that induce disease symptoms in specific host genotypes. Here we present the genome sequence of two further S. nodorum strains (Sn4 and Sn79) that differ in their effector repertoire from the reference. Sn79 is avirulent on wheat and produces no apparent effectors when infiltrated onto many cultivars and mapping population parents. Sn4 is pathogenic on wheat and has virulences not found in SN15. The new strains, sequenced with short-read Illumina chemistry, are compared with SN15 by a combination of mapping and de novo assembly approaches. Each of the genomes contains a large number of strain-specific genes, many of which have no meaningful similarity to any known gene. Large contiguous sections of the reference genome are absent in the two newly sequenced strains. We refer to these differences as “sectional gene absences.” The presence of genes in pathogenic strains and absence in Sn79 is added to computationally predicted properties of known proteins to produce a list of likely effector candidates. Transposon insertion was observed in the mitochondrial genomes of virulent strains where the avirulent strain retained the likely ancestral sequence. The study suggests that short-read enabled comparative genomics is an effective way to both identify new S. nodorum effector candidates and to illuminate evolutionary processes in this species.
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Oliver R. Genomic tillage and the harvest of fungal phytopathogens. THE NEW PHYTOLOGIST 2012; 196:1015-1023. [PMID: 22998436 DOI: 10.1111/j.1469-8137.2012.04330.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/06/2012] [Indexed: 06/01/2023]
Abstract
Genome sequencing has been carried out on a small selection of major fungal ascomycete pathogens. These studies show that simple models whereby pathogens evolved from phylogenetically related saprobes by the acquisition or modification of a small number of key genes cannot be sustained.The genomes show that pathogens cannot be divided into three clearly delineated classes (biotrophs, hemibiotrophs and necrotrophs) but rather into a complex matrix of categories each with subtly different properties. It is clear that the evolution of pathogenicity is ancient, rapid and ongoing. Fungal pathogens have undergone substantial genomic rearrangements that can be appropriately described as 'genomic tillage'. Genomic tillage underpins the evolution and expression of large families of genes - known as effectors - that manipulate and exploit metabolic and defence processes of plants so as to allow the proliferation of pathogens.
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Affiliation(s)
- Richard Oliver
- Australian Centre for Necrotrophic Fungal Pathogens, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6845, Australia
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