Association of two co-occurring mutations at the AvrMlp7 avirulence locus in poplar rust during the breakdown of RMlp7 resistance gene - Institut Agro Montpellier Accéder directement au contenu
Poster De Conférence Année : 2021

Association of two co-occurring mutations at the AvrMlp7 avirulence locus in poplar rust during the breakdown of RMlp7 resistance gene

Résumé

The deployment of plant varieties carrying resistance (R) genes exerts strong selection pressures towards pathogen populations. Several studies reported the rapid evolution of avirulence (Avr) genes to escape R-mediated plant immunity and identified a variety of mechanisms leading to virulence. The poplar rust fungus Melampsora larici-populina is the most damaging pathogen of poplars. A major adaptive event occurred in 1994 with the breakdown of RMlp7 resistance gene in poplar in Europe. Population genomics studies identified a locus in the genome of M. larici-populina, which likely corresponds to the AvrMlp7 candidate avirulence gene. We used a population genetics approach combined with dedicated qPCR assays on a comprehensive set of 281 isolates, covering 27 years (encompassing the resistance breakdown event), to validate the candidate locus and to assess its polymorphism. We found two mechanisms, a point mutation and a deletion, that allowed the pathogen to escape RMlp7-mediated resistance. Six diploid genotypes were thus characterized at the candidate locus (three avirulent and three virulent). In addition, a temporal analysis revealed that the two virulence alleles pre-existed (harbored as avirulent heterozygous genotypes) since the early samplings and were found in association (as virulent genotypes) at the time of the resistance breakdown. Our study documented that, in a diploid pathogen, combining virulence determinisms is adaptive.
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Dates et versions

hal-04137548 , version 1 (06-10-2023)

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Louet Clémentine, Saubin Méline, Andrieux Axelle, Persoons Antoine, Gorse Mathilde, et al.. Association of two co-occurring mutations at the AvrMlp7 avirulence locus in poplar rust during the breakdown of RMlp7 resistance gene: [Poster]. IS-MPMI Congress eSymposium, Pathogen-Host Coevolution — Combating Resistance Breaking in Agriculture, Sep 2021, Online, United States. , 2021, 2021 IS-MPMI Congress: eSymposia Series Abstracts. ⟨10.1094/MPMI-34-9-S2.1⟩. ⟨hal-04137548⟩
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