Plant regeneration

The effect of calcium chloride on callus induction and plant regeneration from cultured immature embryos of Indian barley (Hordeum vulgare L. cultivar BL-2) and seeds of indica rice (Oryza sativa L. cultivar Pusa Basmati-1) has been investigated. Murashige and Skoog's medium containing Gamborg's medium vitamins and 20.7 M, 12.47 M & 0.2 M picloram was used for callus induction, subculture and plant regeneration in barley cultures respectively. Rice callus was induced on Murashige and Skoog's medium supplemented with 11.31M 2,4-dichlorophenoxyacetic acid and subsequently regenerated on MS medium containing 2.68 M 1-naphthaleneacetic acid and 8.87 M 6-benzylaminopurine. The basal media at different stages of culture were supplemented with different levels of calcium chloride (0 to 29.9 mM). Calcium chloride was found to be essential for plant regeneration. Higher level of calcium chloride at various phases of culture prior to regeneration was beneficial for regeneration of both barley and rice cultures. The optimum requirement was same for the two plants though for both the plants this level varied with the phases of culture. Regeneration frequency up to 100% with 2-2.5 folds higher number of regenerated plantlets was achieved when calcium chloride concentration in the induction and subculture media was raised to 14.95 mM and reduced to 2.99 mM in the regeneration medium.

The small millets are quite important in areas of their cultivation as dryland crops, as well as for tribal and hill agriculture. Finger millet-Eleusine coracana, has been the most cultivated and useful small millet crop in India, especially for its nutraceutical qualities. An attempt had been made to develop in vitro regeneration protocol using immature spikes. The immature inflorescence pieces of different sizes were cultured on MS medium supplemented with various growth regulators-2,4-D, 2,4,5-T, pCPA, IAA, Kn and BAP, either alone or in various combinations. Among the various growth regulators investigated, 2,4-D ( 2 mg/l) with Kn (0.5 mg/l) gave maximum callusing response. Effect of developmental stage of immature inflorescence was also studied by collecting immature spikes of different sizes. In cultivar PR-202, a combination of BAP (0.2 mg/l and 2,4-D (2 mg/l) had been found to be very responsive in very young immature spikes (1.25 cm). Successful plant regeneration was obtained from maintained organogenic callus when sub-cultured on BAP supplemented medium.