CALLOGENESIS AND ORGANOGENESIS IN THREE GENOTYPES OF BRASSICA JUNCEA AFFECTED BY EXPLANT SOURCE

In vitro studies of Brassica juncea is indispensable for evaluating its response to different biotic and abiotic stresses and its improvement through biotechnological techniques. In the present study, we sought to evaluate the In vitro response of the three different explants (cotyledons, hypocotyls and roots) of three genotypes of Brassica juncea (UCD-635, RL-18 and NIFA-RAYE). The explants were cultured on MS medium supplemented with different combinations of the auxins (NAA and IAA) and cytokinin (BAP and KIN). All the explants responded significantly to all the hormonal concentrations for different parameters. Cotyledons of all the three genotypes were efficient in producing shoots whereas less number of calli were produced by the cotyledons. BAP 2.0 mgL -1 /NAA 0.2 mgL -1 , BAP 3.0 mgL -1 /NAA 0.5 mgL -1 and Kin 2.0 mgL -1 /IAA 0.2 mgL -1 and Kin 3.0 mgL -1 /IAA 0.5 mgL -1 produced shoots efficiently from the cotyledon explants of the two genotypes, UCD-635 and RL-18. Hypocotyls were found efficient for callus production while their response for shoots formation was slower as more number of days were taken by hypocotyls to produce shoots. Roots were efficient for callus and root formation but neither of the root explants produced shoots on any of the used hormonal concentration. Based on our study, hypocotyls and roots could be the preferred explants when more and vigorous callus formation is required, while cotyledons could be the preferred explants where regeneration is needed such as in genetic transformation experiments.