Genome scans on experimentally evolved populations of the cyst nematode Globodera pallida reveal distinct candidate regions for the adaptation to colinear resistant factors in potato
The use of alternative methods to control cyst nematode populations has accelerated since the ban of chemical nematicides in Europe. The resistant QTL GpaVvrn, derived from the wild species Solanum vernei, is widely present in resistant European potato cultivars and provides a strong protection against Globodera pallida populations although a risk of resistance breakdown has already been demonstrated in both experimental evolution studies and field populations. The wild relative S. sparsipilum, harbouring the resistant QTL GpaVspl, would be an interesting alternative source of resistance to control virulent G. pallida. The goal of the present study was to understand the genomics of adaptation of the nematode to those both colinear resistant QTLs. Starting with two natural populations, an experimental evolution approach allowed, after 10 generations on resistant potato genotypes, to select independent nematode lineages adapted to each QTL. These virulent lineages were analyzed through a combination of phenotyping and genome scans approaches. Phenotyping enabled the quantification of virulence levels and confirmed resistance breakdowns. Pool-seq whole genome sequencing followed by genome scan analyses identified genomic regions under selection, potentially involved in the adaptative mechanisms to each resistance factor. Candidate genes within these regions provided insights into the genetic basis of adaptation, revealing effectors known to suppress plant immunity. As genome scans highlighted distinct genomic regions for the adaptation to both resistant factors, we were able to predict and to phenotypically confirm the absence of cross-virulence between nematode lineages evolving on GpaVvrn and GpaVspl. These findings have significant implications for the design of effective and sustainable resistance management strategies.