Elucidation of Genetic Relationships in the Genus Cajanus Using Random Amplified Polymorphic DNA Marker Analysis

Abstract

In this present investigation, a total of 27 RAPD primers were used to elucidate the genetic relationships between cultivated Cajanus cajan cultivars and 10 allied species of primary, secondary and tertiary gene pool, including C. cajanifolius, C. scarabaeoides, C. platycarpus, C. albicans, C. volubilis, C. sericeus, C. acutifolius, C. lineatus, C. lanceolatus and C. reticulates. All primers showed polymorphism at species level and produced 215 unequivocal polymorphic bands, with an average of 7.96 bands per primer. These polymorphic primers exhibited variation with regard to average band informativeness, resolving power, and showed high polymorphism information content value. No single primer was able to distinguish between all the two cultivars of C. cajan and ten allied species of Cajanus, but several species specific amplified fragments were observed. The pair wise Jaccard’s similarity coefficient values revealed high level of inter-specific genetic variation in the genus Cajanus. Cluster analysis exhibited the grouping of two C. cajan accessions with C. cajanifolius in one cluster, while except C. platycarpus, all the nine wild Cajanus species belonging to the secondary and tertiary gene pool form another cluster. The present analysis more or less agreed with the sectional classification of the genus Cajanus, and it has been hypothesized that cultivated pigeonpea has evolved through multi-genomic interaction through C. cajanifolius, and it has experienced minor genomic reorganization during its divergence. Again, identification of species specific amplification pattern substantiated the utility of RAPD markers on selection of suitable species to transfer the desirable trait into cultivated C. cajan, through marker aided breeding for its genetic augmentation, and also for the effective management of genetic resources of C. cajan.