Experimentally evolved populations of the potato cyst nematode Globodera pallida allow the targeting of genomic footprints of selection due to host adaptation

In the current agronomical context of pesticide use reduction, deciphering the genetic bases of pathogen adaptation to plant resistances is of major importance to improve their durability. Knowledge of the virulence gene frequencies in pathogens populations could indeed allow the prediction of their durability before deployment. Globodera pallida is a major pest of potato crop for which a promising resistance QTL, GpaVvrn, has been identified in Solanum vernei. An experimental evolution study, in which G. pallida lineages evolved on resistant or susceptible potato genotypes for up to eight generations, previously showed that G. pallida was able to rapidly overcome GpaVvrn resistance. However it was not known if enough genetic mixing occurred in these lineages to be able to detect islands of differentiation in a genome scan approach. Here, we investigated this question using 53 polymorphic microsatellite markers distributed along the genome and three different tests based on genetic differentiation and heterozygosity. We identified eight outlier loci, indicative of genomic regions putatively involved in host adaptation. Several loci were identified by multiple detection methods and/or in two independent adapted lineages. We also showed that some identified candidate genomic regions seem to be also involved in the overcoming of nematode resistance in a genotype harbouring the same resistance QTL in a different genetic background. These results validate the feasibility of a genome scan approach on a biological material coming from short experimental evolution, and encourage to perform a high coverage genome scan using whole genome resequencing. This article is protected by copyright. All rights reserved.