QTL-seq reveals a major root-knot nematode resistance locus on chromosome 11 in rice ( L.).

The root-knot nematode is a serious pest in rice affecting production in many rice growing areas. Natural host resistance is an attractive control strategy because the speed of the parasite's life cycle and the broad host range it attacks make other control measures challenging. Although resistance has been found in the domesticated African rice and the wild rice species the introgression of resistance genes to Asian rice is challenging. Resistance due to a major gene in would greatly aid breeding. Recently two accessions resistant to have been identified in a screen of 332 diverse cultivars. In this study, these two resistant cultivars, LD 24 (an from Sri Lanka) and Khao Pahk Maw (an from Thailand), were crossed with a moderately susceptible cultivar, Vialone Nano (a from Italy). Approximately 175 F progeny of both populations were screened for susceptibility to infection. Between 20 and 23 individuals with highest and lowest galls per plants were pooled to make susceptible and resistant bulks which were sequenced to conduct bulked segregant analysis using the QTL-seq method. This revealed a nematode resistance locus from 23 Mbp to the bottom of rice chromosome 11 in both crosses suggesting a rare introgression of the same locus is responsible for resistance in both cultivars. While this information can be used in marker-assisted breeding, analysis of available SNP data revealed candidate loci and genes worthy of further investigation for gene identification.