Molecular genetic diversity and linked resistance to ascochyta blight in Australian chickpea breeding materials and their wild relatives

Simple sequence-repeat (SSR) and sequence characterised amplified regions (SCARs) have been used to characterise the genetic diversity of chickpea germplasm. A set of 48 genotypes comprising cultigen, landraces, and wild relatives important for breeding purposes was used to determine the genetic similarity between genotypes and to assess the association between ascochyta blight ( AB) and SCAR phenotypes. The 21 SSR markers amplified a total of 370 alleles, with an average of similar to 17 alleles per SSR locus among the 48 genotypes. Polymorphic information content (PIC) values ranged from 0.37 for the XGA13 locus to 0.93 for the XGA106. Principal coordinate analysis (PCO) of genetic similarity (GS) estimates revealed a clear differentiation of the chickpea genotypes into 5 groups, which were generally consistent with available pedigree information. Comparison of SCAR and AB phenotypes enabled us to tag the common source(s) of AB resistance in the breeding collection. Based on the SCAR phenotypes, it was evident that the studied chickpea genotypes, including worldwide-known AB-resistant lines (ICC12004, ILC72, ILC3279), carry at least one common source of resistance to AB. Since SSR markers are polymerase chain reaction (PCR)-based markers, highly polymorphic, and amenable to high-throughput technologies, they are therefore well suited for studies of genetic diversity and cultivar identification in chickpea. The broad level of genetic diversity detected in the chickpea germplasm should be useful for selective breeding for specific traits such as AB, backcrossing, and in enhancing the genetic base of breeding programs.