Fine Mapping of QTLs for Ascochyta Blight Resistance in an Interspecific Pea Population

Ascochyta blight is a one of the major pea diseases internationally and can cause significant grain yield loss under wet conditions. In our previous study, nine quantitative trait loci (QTLs) were identified for ascochyta blight resistance based on a single nucleotide polymorphism (SNP) linkage map of an interspecific pea mapping population (PR-19) developed from a cross between Alfetta (Pisum sativum) and P651 (P. fulvum). To fine map the consistent QTLs abI-IV-2 and abIII-1, heterogeneous inbred family (HIF) populations, HIF-224 and HIF-173 were developed from lines PR-19-224 and PR-19-173, respectively. HIFs showed a wide range of variation for reaction to ascochyta blight under field conditions in Saskatoon and Rosthern locations in Saskatchewan in 2015 and 2016. Genotyping of 51 PR-19 lines using genotyping-by-sequencing (GBS) identified additional SNP markers within abI-IV-2 and abIII-1 QTL regions. Twelve and 5 additional SNP markers for abI-IV-2 and abIII-1, representative of individual locus, in addition to the existing SNP markers were genotyped on HIF-224 and HIF-173 populations using Kompetitive Allele-Specific PCR (KASP) assays, respectively. Fine mapping of the two major ascochyta resistance QTLs abI-IV-2 and abIII-1, based on SNP genotyping and ascochyta blight data of the two HIF families will be presented.