A new QTL for Ascochyta blight resistance in an RIL population derived from an interspecific cross in chickpea

Abstract

A linkage map in a population of recombinant inbred lines (RILs) derived from an interspecific cross between Cicer arietinum (ILC72) × Cicer reticulatum (Cr5-10), resistant and susceptible to blight, caused by Ascochyta rabiei, respectively, was obtained using RAPD, ISSR, STMS, isozyme (Pdf6) and flower colour (pink/white) markers. The map comprised ten linkage groups and covered a distance of 601.2 cM. When the population was evaluated for reaction to Ascochyta blight under field conditions by determining the Area Under the Disease Progress Curve (AUDPC), the distribution of frequencies was bimodal: most of the lines had an intermediate reaction, fewer were nearly as susceptible as the susceptible parent and none had values close to the resistant parent. A QTL explaining 28% of the variation in resistance was located in linkage group 2 (LG2). Five RAPD markers on this linkage group showed significant association with resistance (OPX04372, UBC881621, OPAI09746, OPAI09352 and OPAC12700) and the major QTL peak lay midway between OPAI09746 and UBC881621 which are 14.1 cM apart. Contrary to other studies, no association of linkage group 4 with resistance was found. The QTL for resistance to Ascochyta blight in this study is therefore different from QTLs for this character reported in other interspecific crosses and may be the same as that reported in linkage group 2 in intraspecific crosses where genes for resistance to races of Fusarium oxysporum f. sp. ciceri, causing wilt, are also located.