QTL Analysis for Ascochyta blight Resistance in

Microsatellites have become markers of choice for molecular mapping and marker assisted selection of key traits such as disease resistance in many crop species. The aim of this study was to construct a genetic linkage map and analyze quantitative trait loci (QTLs) for leaf size and ascochyta blight resistance in chickpea (Cicer arietinum L.), as well as quantify the contribution of each QTL to observed phenotypic variation. Fifty-eight SSR markers and one morphological marker (flower color) were mapped on 83 F2 individuals and F2:3 families derived from the cross ICC 12004 (resistant) ´ Bivanij (susceptible local cultivar) at the International Center for Agricultural Research at Dry Area (ICARDA). The linkage map comprised eight linkage groups, excluding flower color which didnt assign to any linkage group. Area under disease progress curve (AUDPC) was used to evaluate the F2 population and F3 families. A fain's test based on means and variances of the ascochyta blight reaction of F3 families showed that a few genes segregated in the population. Using composite interval mapping, one and three genomic regions were detected, which were in association with leaf size and reaction to ascochyta blight, respectively. One QTL on LG7 accounted for 15% of phenotypic variation for leaf size. Furthermore, three QTLs on LG3, LG4 and LG6 accounted for 46.5% of the total estimated phenotypic variation for reaction to ascochyta blight. Fine mapping of the QTLs identified in this study would lead to the identification of markers that could be used for marker-assisted selection of chickpea genotypes with resistance to acochyta blight. These findings are particular pertinent considering that we used Ascochyta rabiei pathotype III and ICC 12004 (resistant to pathotype III) for the first time.