The adaptation of potato cyst nematodes to overcome potato resistance is specific to each resistance factor, meaning that cross-infection does not occur

NEM-EMERGE partners at INRAE have recently published an article in the Molecular Ecology journal, where they report their findings regarding the way potato cyst nematodes develop adaptation to nematode-resistant potato plants.

In the last decade, more stringent environmental regulations in Europe have banned the use of chemical nematicides, making plant genetic resistance a central pillar of sustainable crop protection strategies. Even though resistance can provide high levels of protection, it is not a perfect control option, as nematodes have the potential to overcome plant resistance. Indeed, resistance breakdowns have already been reported in natural populations.

With the aim of understanding the genomic basis behind the adaptation capacity of potato cyst nematodes, a group of researchers from three French research laboratories, among which are NEM-EMERGE partners, carried out a study based on two different potato genotypes resistant to potato cyst nematodes. One of them was derived from the wild species Solanum vernei, whose resistance genetic region is well known, and several studies have shown that cyst nematode populations are able to adapt to this resistance. Conversely, the resistance factor from the other potato species used, Solanum sparsipilum, had not been deployed in potato cultivars, so limited information was available on the ability of nematode populations to overcome it. However, both genetic regions are located in a collinear (similar) position on the potato genome, so scientists found it essential to investigate the potential ability of the nematodes virulent to one of the potato species to cross-infect the other species.

Starting with two natural populations growing on resistant potato plants, researchers were able to see that after 10 generations, there were nematode lineages adapted to each resistance. These virulent lineages were analysed through a combination of phenotyping and genome scans approaches. Phenotyping enabled the quantification of virulence levels and confirmed resistance breakdowns. Genome sequencing and scan analyses revealed the genomic regions on the nematodes, and candidate genes potentially involved in the adaptive mechanisms to each resistance factor. This in-depth analysis showed that distinct genomic regions are involved in the nematode’s adaptation to those resistance factors which enabled researchers to predict and confirm that adaptation to one resistance does not confer any adaptive advantage for overcoming the other.