Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants
Brassica napus (canola) cultivars and isolates of the blackleg fungus, Leptosphaeria maculans interact in a ‘gene for gene’ manner whereby plant resistance (R) genes are complementary to pathogen avirulence (Avr) genes. Avirulence genes encode proteins that belong to a class of pathogen molecules kn...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
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Public Library of Science
2010
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| Online Access: | http://hdl.handle.net/20.500.11937/17601 |
| _version_ | 1848749508746280960 |
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| author | Van de Wouw, A. Cozijnsen, A. Hane, J. Brunner, P. McDonald, B. Oliver, Richard Howlett, B. |
| author_facet | Van de Wouw, A. Cozijnsen, A. Hane, J. Brunner, P. McDonald, B. Oliver, Richard Howlett, B. |
| author_sort | Van de Wouw, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Brassica napus (canola) cultivars and isolates of the blackleg fungus, Leptosphaeria maculans interact in a ‘gene for gene’ manner whereby plant resistance (R) genes are complementary to pathogen avirulence (Avr) genes. Avirulence genes encode proteins that belong to a class of pathogen molecules known as effectors, which includes small secreted proteins that play a role in disease. In Australia in 2003 canola cultivars with the Rlm1 resistance gene suffered a breakdown of disease resistance, resulting in severe yield losses. This was associated with a large increase in the frequency of virulence alleles of the complementary avirulence gene, AvrLm1, in fungal populations. Surprisingly, the frequency of virulence alleles of AvrLm6 (complementary to Rlm6) also increased dramatically, even though the cultivars did not contain Rlm6. In the L. maculans genome, AvrLm1 and AvrLm6 are linked along with five other genes in a region interspersed with transposable elements that have been degenerated by Repeat-Induced Point (RIP) mutations. Analyses of 295 Australian isolates showed deletions, RIP mutations and/or non-RIP derived amino acid substitutions in the predicted proteins encoded by these seven genes. The degree of RIP mutations within single copy sequences in this region was proportional to their proximity to the degenerated transposable elements. The RIP alleles were monophyletic and were present only in isolates collected after resistance conferred by Rlm1 broke down, whereas deletion alleles belonged to several polyphyletic lineages and were present before and after the resistance breakdown. Thus, genomic environment and exposure to resistance genes in B. napus has affected the evolution of these linked avirulence genes in L. maculans. |
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| format | Journal Article |
| id | curtin-20.500.11937-17601 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:22:03Z |
| publishDate | 2010 |
| publisher | Public Library of Science |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-176012017-09-13T13:36:45Z Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants Van de Wouw, A. Cozijnsen, A. Hane, J. Brunner, P. McDonald, B. Oliver, Richard Howlett, B. Brassica napus (canola) cultivars and isolates of the blackleg fungus, Leptosphaeria maculans interact in a ‘gene for gene’ manner whereby plant resistance (R) genes are complementary to pathogen avirulence (Avr) genes. Avirulence genes encode proteins that belong to a class of pathogen molecules known as effectors, which includes small secreted proteins that play a role in disease. In Australia in 2003 canola cultivars with the Rlm1 resistance gene suffered a breakdown of disease resistance, resulting in severe yield losses. This was associated with a large increase in the frequency of virulence alleles of the complementary avirulence gene, AvrLm1, in fungal populations. Surprisingly, the frequency of virulence alleles of AvrLm6 (complementary to Rlm6) also increased dramatically, even though the cultivars did not contain Rlm6. In the L. maculans genome, AvrLm1 and AvrLm6 are linked along with five other genes in a region interspersed with transposable elements that have been degenerated by Repeat-Induced Point (RIP) mutations. Analyses of 295 Australian isolates showed deletions, RIP mutations and/or non-RIP derived amino acid substitutions in the predicted proteins encoded by these seven genes. The degree of RIP mutations within single copy sequences in this region was proportional to their proximity to the degenerated transposable elements. The RIP alleles were monophyletic and were present only in isolates collected after resistance conferred by Rlm1 broke down, whereas deletion alleles belonged to several polyphyletic lineages and were present before and after the resistance breakdown. Thus, genomic environment and exposure to resistance genes in B. napus has affected the evolution of these linked avirulence genes in L. maculans. 2010 Journal Article http://hdl.handle.net/20.500.11937/17601 10.1371/journal.ppat.1001180 Public Library of Science fulltext |
| spellingShingle | Van de Wouw, A. Cozijnsen, A. Hane, J. Brunner, P. McDonald, B. Oliver, Richard Howlett, B. Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title | Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title_full | Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title_fullStr | Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title_full_unstemmed | Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title_short | Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host Plants |
| title_sort | evolution of linked avirulence effectors in leptosphaeria maculans is affected by genomic environment and exposure to resistance genes in host plants |
| url | http://hdl.handle.net/20.500.11937/17601 |