Effect of gamma irradiation on cell proliferation and regeneration in explanted tissues of pigeon pea, Cajanus cajan (L) mills P

Effects on the developmental morphology of Cajanus seeds irradiated with ⁶⁰Cogamma rays have been investigated in vitro. Seeds exposed to 5 kR produced a cluster of adventitious roots on a “callusing medium” (modified Murashige and Skoog nutrient solution) while the hypocotyl explants of germinated seedlings were stimulated to cell proliferation and abundant callusing which, on a “differentiating medium” (modified medium) regenerated shoot buds and plantlets. In controls and with higher doses growth was limited to the development of a spongy tissue to form a small callus mass from seeds and a restricted callus proliferation from excised hypocotyls of irradiated seeds. Only calluses exposed to 5 kR differentiated plantlets. However, callus tissues derived from the 5 kR treatment were highly friable and amenable for release of protoplasts in large numbers on enzymatic digestion of cell walls of cells grown as suspensions. Mesophyll cell protoplasts obtained from the tissue culture-induced plant showed spontaneous adhesion and fusion.