Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction
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...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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FRONTIERS MEDIA SA
2020
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| Online Access: | http://hdl.handle.net/20.500.11937/83209 |
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| author | Phan, Huyen T. T. Jones, Darcy Rybak, Kasia Dodhia, Kejal Lopez-Ruiz, Francisco Valade, R. Gout, L. Lebrun, M.H. Brunner, P.C. Oliver, Richard Tan, Kar-Chun |
| author_facet | Phan, Huyen T. T. Jones, Darcy Rybak, Kasia Dodhia, Kejal Lopez-Ruiz, Francisco Valade, R. Gout, L. Lebrun, M.H. Brunner, P.C. Oliver, Richard Tan, Kar-Chun |
| author_sort | Phan, Huyen T. T. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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. |
| first_indexed | 2025-11-14T11:21:21Z |
| format | Journal Article |
| id | curtin-20.500.11937-83209 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:21:21Z |
| publishDate | 2020 |
| publisher | FRONTIERS MEDIA SA |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-832092021-05-06T02:46:41Z Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction Phan, Huyen T. T. Jones, Darcy Rybak, Kasia Dodhia, Kejal Lopez-Ruiz, Francisco Valade, R. Gout, L. Lebrun, M.H. Brunner, P.C. Oliver, Richard Tan, Kar-Chun Science & Technology Life Sciences & Biomedicine Plant Sciences septoria nodorum blotch SSR effector population wheat STAGONOSPORA-NODORUM PHAEOSPHAERIA-NODORUM MATING-TYPE SEXUAL REPRODUCTION GENETIC-VARIABILITY GENOTYPIC DIVERSITY PLANT-PATHOGENS WHEAT DISEASE POPULATIONS 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. 2020 Journal Article http://hdl.handle.net/20.500.11937/83209 10.3389/fpls.2019.01785 English http://creativecommons.org/licenses/by/4.0/ FRONTIERS MEDIA SA fulltext |
| spellingShingle | Science & Technology Life Sciences & Biomedicine Plant Sciences septoria nodorum blotch SSR effector population wheat STAGONOSPORA-NODORUM PHAEOSPHAERIA-NODORUM MATING-TYPE SEXUAL REPRODUCTION GENETIC-VARIABILITY GENOTYPIC DIVERSITY PLANT-PATHOGENS WHEAT DISEASE POPULATIONS Phan, Huyen T. T. Jones, Darcy Rybak, Kasia Dodhia, Kejal Lopez-Ruiz, Francisco Valade, R. Gout, L. Lebrun, M.H. Brunner, P.C. Oliver, Richard Tan, Kar-Chun Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title | Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title_full | Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title_fullStr | Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title_full_unstemmed | Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title_short | Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction |
| title_sort | low amplitude boom-and-bust cycles define the septoria nodorum blotch interaction |
| topic | Science & Technology Life Sciences & Biomedicine Plant Sciences septoria nodorum blotch SSR effector population wheat STAGONOSPORA-NODORUM PHAEOSPHAERIA-NODORUM MATING-TYPE SEXUAL REPRODUCTION GENETIC-VARIABILITY GENOTYPIC DIVERSITY PLANT-PATHOGENS WHEAT DISEASE POPULATIONS |
| url | http://hdl.handle.net/20.500.11937/83209 |