Fine Mapping and Identification of a Fusarium Wilt Resistance Gene FwS1 in Pea

Abstract Pea Fusarium wilt, incited by Fusarium oxysporum f. sp. pisi (Fop), has always been a devastating disease that causes severe yield losses and economic damage in pea-growing regions worldwide. The utilization of pea cultivars carrying resistance gene is the most efficient approach for managing this disease. In order to finely map resistance gene, a F2 population was established through the cross between Shijiadacaiwan 1 (resistant) and Y4 (susceptible). The resistance genetic analysis indicated that the Fop resistance in Shijiadacaiwan 1 was governed by a single dominant gene, named as FwS1. Based on the bulked segregant analysis sequencing (BSA-seq) analyses, the gene FwS1 was initially detected on chromosome 6 (i.e., linking group Ⅱ, chr6LG2), and subsequent linkage mapping with 589 F2 individuals fine-mapped the gene FwS1 into a 91.4 kb region. The further functional annotation and haplotype analysis confirmed that the gene Psat6g003960, characterized by a NB-ARC (nucleotide-binding adaptor shared by APAF-1, R proteins, and CED-4) domain, was considered as the most promising candidate gene. The encoding amino acids were altered by a “T/C” single-nucleotide polymorphism (SNP) in the first exon of the Psat6g003960, resulting in the observed differences of Fop resistance in peas. Based on this SNP locus, the molecular marker A016180 was determined to be a diagnostic marker for FwS1 by validating its specificity in both pea accessions and genetic populations with different genetic backgrounds. The FwS1 with diagnostic KASP marker A016180 could facilitate marker-assisted selection in resistance pea breeding in pea. In addition, upon comparing the candidate gene Psat6g003960 of 74SN3B and SJ1, it was noted that their sequences are identical, suggesting that the FwS1 and Fwf may be the same resistance gene against Fusarium wilt.