Genome Structure and Reproductive Behaviour Influence the Evolutionary Potential of a Fungal Phytopathogen
Open Access
- 31 October 2012
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Pathogens
- Vol. 8 (11), e1003020
- https://doi.org/10.1371/journal.ppat.1003020
Abstract
Modern agriculture favours the selection and spread of novel plant diseases. Furthermore, crop genetic resistance against pathogens is often rendered ineffective within a few years of its commercial deployment. Leptosphaeria maculans, the cause of phoma stem canker of oilseed rape, develops gene-for-gene interactions with its host plant, and has a high evolutionary potential to render ineffective novel sources of resistance in crops. Here, we established a four-year field experiment to monitor the evolution of populations confronted with the newly released Rlm7 resistance and to investigate the nature of the mutations responsible for virulence against Rlm7. A total of 2551 fungal isolates were collected from experimental crops of a Rlm7 cultivar or a cultivar without Rlm7. All isolates were phenotyped for virulence and a subset was genotyped with neutral genetic markers. Virulent isolates were investigated for molecular events at the AvrLm4-7 locus. Whilst virulent isolates were not found in neighbouring crops, their frequency had reached 36% in the experimental field after four years. An extreme diversity of independent molecular events leading to virulence was identified in populations, with large-scale Repeat Induced Point mutations or complete deletion of AvrLm4-7 being the most frequent. Our data suggest that increased mutability of fungal genes involved in the interactions with plants is directly related to their genomic environment and reproductive system. Thus, rapid allelic diversification of avirulence genes can be generated in L. maculans populations in a single field provided that large population sizes and sexual reproduction are favoured by agricultural practices.This publication has 68 references indexed in Scilit:
- Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutationsNature Communications, 2011
- Evolution of Linked Avirulence Effectors in Leptosphaeria maculans Is Affected by Genomic Environment and Exposure to Resistance Genes in Host PlantsPLoS Pathogens, 2010
- Inference on population history and model checking using DNA sequence and microsatellite data with the software DIYABC (v1.0)BMC Bioinformatics, 2010
- Fitness cost of virulence differs between the AvrLm1 and AvrLm4 loci in Leptosphaeria maculans (phoma stem canker of oilseed rape)European Journal of Plant Pathology, 2009
- RIPCAL: a tool for alignment-based analysis of repeat-induced point mutations in fungal genomic sequencesBMC Bioinformatics, 2008
- The Origins of Plant Pathogens in Agro-EcosystemsAnnual Review of Phytopathology, 2008
- The plant immune systemNature, 2006
- Major Gene and Polygenic Resistance to Leptosphaeria maculans in Oilseed Rape (Brassica napus)European Journal of Plant Pathology, 2006
- Advances in understanding molecular mechanisms of fungicide resistance and molecular detection of resistant genotypes in phytopathogenic fungiCrop Protection, 2005
- Analysis of Gene Diversity in Subdivided PopulationsProceedings of the National Academy of Sciences of the United States of America, 1973