Mapping, stacking and characterization of a novel resistance haplotype against GpaVvrn-virulent Globodera pallida derived from wild potato relative Solanum brevicaule

Abstract

Potato production is threatened by pests and pathogens. Among the most harmful are the potato cyst nematodes (PCN), including Globodera pallida. The major control measures are potato cultivars harbouring resistance genes. However, virulent nematode populations are breaking through the most broadly applied resistance genes, and therefore novel resistance genes are required to keep control of G. pallida. In this study we map a resistance locus in wild potato relative Solanum brevicaule to the bottom of chromosome 11 (42.83 - 42.85 Mb) using a k-mer based bulked segregant analysis and name the resistant haplotype GpaXIbrc. The presence of the GpaXIbrc marker in the potato genome significantly increases resistance against a GpaVvrn-virulent G. pallida population (AMPOP01). Furthermore, the GpaXIbrc haplotype was stacked with three other resistance haplotypes: GpaXItar, GpaVvrn, and GpaIXvrn. Stacking of the novel GpaXIbrc haplotype to these other resistance haplotypes resulted in a significant increase in resistance. The largest effect was seen in combinations with 'major' resistance haplotypes GpaVvrn + GpaIXvrn and GpaXItar + GpaXIbrc. To determine whether we are dealing with a novel allele, the resistance mechanism underlying the GpaXIbrc haplotype was described after performing an in vitro bioassay. The resistance mechanism was different from GpaXIspl as described in literature, which is also localized at the bottom of chromosome 11. Therefore, we conclude that we found a novel resistance allele originating from S. brevicaule.