SSR mapping of genes conditioning soybean resistance to six isolates of Xanthomonas axonopodis pv. glycines

Bacterial leaf pustule (BLP), caused by Xanthomonas axonopodis pv. glycines, is one of the most prevalent bacterial diseases in plants. Quantitative trait loci (QTLs) for resistance to BLP in soybean (Glycine max [L.] Merr.) were identified using simple sequence repeat (SSR) markers, and the consistency of QTL detection across bacterial isolates as well as across greenhouse and field experiments was examined. Recombinant inbred lines (RILs) derived from a cross of BLP-susceptible 'Suwon157' and BLP-resistant 'Danbaekkong' were utilized to identify QTLs conditioning resistance to BLIP with 76 SSR markers. For phenotypic analysis, six isolates of X. axonopodis were collected from different geographical locations. A combination of single-factor analysis of variance and multiple regression analysis revealed that three QTLs conditioned resistance to BLP in the field. Under greenhouse conditions, one to four QTLs were revealed to be associated with resistance to each isolate. Satt372 on linkage group (LG) D2 was associated with resistance to all six isolates under greenhouse and field conditions, indicating that resistance to BLP was mainly controlled by a single major gene tightly linked to Satt372. Several niinor QTLs on LG A1, C1, F, L, and O were also found to condition resistance to various isolates.