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Conference papers

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

Abstract : 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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Conference papers
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https://hal.inrae.fr/hal-03588311
Contributor : Dominique Fournier Connect in order to contact the contributor
Submitted on : Thursday, February 24, 2022 - 4:50:59 PM
Last modification on : Friday, August 5, 2022 - 10:58:14 AM

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  • HAL Id : hal-03588311, version 1
  • WOS : 000754736500040

Citation

Louet C, Méline Saubin, Axelle Andrieux, A. Persoons, Gorce M, et al.. Association of two co-occurring mutations at the AvrMlp7 avirulence locus in poplar rust during the breakdown of RMlp7 resistance gene. Molecular Mechanism & Structure— Zooming in on Plant Immunity, Jul 2021, e-symposia, Germany. ⟨hal-03588311⟩

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