Selection of nematodes by resistant plants has implications for local adaptation and cross-virulence
Résumé
The variability of resistance durability in different potato genotypes harbouring the same resistance QTL but differing by their genetic background was explored. The indirect consequences of the resistance adaptation in terms of local (i.e. genotype-specific) adaptation and cross-virulence was also investigated. Following the virulence of the potato cyst nematode Globodera pallida in a long-term experimental evolution protocol, the results showed that nematode populations were able to adapt to the resistance of four potato genotypes carrying the QTL GpaV from Solanum vernei, and that the plant genetic background has an impact upon the durability of resistance. The pattern of local adaptation observed here indicates that divergent selection has occurred during the experimental evolution performed from the same initial nematode population, and revealed a trade-off between the adaptation to a resistant potato genotype and the adaptation to another resistant genotype differing in its genetic background. In terms of cross-virulence between potato genotypes derived from different resistance sources (S. sparsipilum and S. spegazzinii), this study shows that the adaptation to resistance QTL GpaVvrn does not necessarily allow the adaptation to collinear GpaV loci. The results presented here could be useful for predicting evolution of nematode populations in natural agro-ecosystems and identifying durable strategies for resistance deployment.