In vitro propagation of Cajanus cajan × C. cajanifolius hybrid and its characterization using cyto-morphological and SSR markers

Cajanus cajanifolius , the putative progenitor species of pigeonpea ( C. cajan ), has many agro-economic traits that deserve attention for introgression into pigeonpea cultivars. However, unidirectional compatibility creates barriers for interspecific hybridization and alien gene transfer between these two species. In the present study, very low percentage of pod setting and F 1 seed germination were observed. Thus, attempts were made for the propagation of interspecific F 1 hybrids in vitro, and an efficient in vitro propagation protocol has been optimized. Excised cotyledonary explants of F 1 hybrids were cultured on both MS and Blaydes’ medium supplemented with NAA, BAP and GA 3 at various combinations and concentrations. MS medium with BAP (25 μM) was most suitable for multiple shoot induction. MS medium was found to be superior for both multiple shoot and root induction from cotyledonary explants. Cyto-morphological and SSR marker based analysis confirmed the hybridity of the micro-propagated F 1 plantlets. Meiocytes of the regenerated F 1 hybrids experienced chromosome heteromorphism during diakinesis leading to laggard and bridge formation at anaphase-I. The present study evidenced the scope of interspecific hybridization between C. cajan and C. cajanifolius aiming at transmission of stress tolerant genes from C. cajanifolius to the cultivated gene pool of pigeonpea for broadening its genetic base.