Genetic analysis of resistance to Ascochyta rabiei in chickpea

Aschochyta blight (caused by Ascochyta rabiei) is the major chickpea disease and production constraint all over the world. The use of resistance genes appears to be the most suitable and reliable way to control the disease. The identification of molecular markers associated to resistance genes might help plant breeders producing new resistant varieties. To this purpose, two cultivars with different reaction to Aschochyta blight, i.e. Sultano (resistant) and Calia (susceptible) were reciprocally crossed, and the individual plants of an F3 segregating generation were scored for reaction to A. rabiei. The ratio resistant/susceptible varied according to the maternal parent, thus supporting a maternal influence on the trait transmission. Appropriate segregant families were analysed using the "Bulked segregant analysis" in which two pooled DNA samples were used to identify RAPD markers possibly associated with the discriminant character. None of the 15 polymprphic bands identified (out of 60 primers used) were associated to resistance or susceptibility. The results strongly suggest that the resistance observed in Sultano is due to the action of two complementary genes with superimposed maternal influence. The possible consequences of the use of phenotypic character, such as reaction to a pathogen, in the selection of specific genotypes are also discussed.