Genetics of Ascochyta Blight Resistance in Chickpea

Available genetic variation for ascochyta blight resistance in genus Cicer has prompted interest in the development and use of autumn sown resistant chickpea cultivars. A thorough understanding of the mode of inheritance of resistance to ascochyta blight in chickpea would assist the breeding efforts. In order to determine the number of genes, as well as to evaluate heritability and action of genes conferring blight resistance and leaf size in chickpea, two genotypes, Iranian local-Bivanij and ICC 12004 were crossed. Parents along with F1, F2 and F3 generations were sown in a Randomized Complete Block Design with three replications at International Center for Agricultural Research in the Dry Areas (ICARDA) under artificial infection conditions. Results showed that, in F2 and F3 generations, ratio of resistance to susceptible plants didnt show significant differences with the respective expected ratios of 9:7 and 5:3. There was a negative correlation observed between leaf size and blight score, meaning that, large leaf genotypes are more susceptible to ascochyta blight. Generation means analysis for resistance to blight revealed that, in this study, additive components played the main role in blight resistance variability, while dominant ones had a significant contribution in variation for leaf size. For these two traits, dominance effects (h) and dominance × dominance interaction (l) had opposite signs which may show the presence of a duplicate epistasis. With respect to these findings, genotypes of the resistant parents could be considered as R1R1R2R2. According to these results, breeding programs could be suggested which appropriately use additive variance for gene pyramiding that can lead to developing ascochyta resistant genotypes in chickpea.