GAMMA RAYS INDUCED IN VITRO MUTAGENESIS AND MOLECULAR MARKER-ASSISTED SELECTION OF MUTANTS IN GRAPEVINE

In vitro mutagenesis was attempted in Pusa Seedless grape (Vitis vinifera L.). In vitro proliferated cultures were subjected to different gamma irradiation doses 0, 5, 10, 20, 30, 40 and 50 Gy using ⁶⁰Co as a source. The gamma-irradiated cultures were then aseptically subcultured onto the half-strength MS basal medium supplemented with 2.0 mg L^-1 indole-3-butyric acid with 200 mg L^-1 activated charcoal. Ten Gy was found as the LD50 dose on the basis of survival of microcuttings and their subsequent in vitro growth. The putative mutants were in vitro multiplied up to υM3 population and hardened, then screened for isolation of solid mutants using the RAPD analysis using 76 primers. Out of thirty putative mutants isolated based on the morphological characters; eleven solid mutants (36.6%) were identified with seven RAPD primers showing complete polymorphism. The identified solid mutants were then further cloned in vitro, hardened and subsequently transferred to glasshouse. The integrated approach suggested could be useful for carrying out the in vitro mutation-assisted breeding and subsequent selection of solid mutants using molecular markers in grape and other heterozygous perennial fruit crops.