High frequency plant regeneration from desiccated calli of indica rice (Oryza Sativa l.)

An efficient and reproducible protocol is required to achieve high frequency transformation from transformed calli. We report here high frequency plant regeneration from mature seed derived embryogenic calli of two recalcitrant indica rice cultivars HKR-46 and HKR-126 after partial desiccation treatment. Embryogenic and nodular callus was initiated on MS basal medium supplemented with 2.5 mg l^-1 2,4-D, 500 mg l^-1 proline, 500 mg l^-1 casein hydrolysate, 30 g l^-1 sucrose and 2.5 g l^-1 gelrite. Several media with different combinations of growth regulators were tried. Maximum shoot regeneration frequency (63%) was observed in partially desiccated calli for 48 h in cv. HKR 46 and 82.1 per cent in cv. HKR-126 on the MS modified medium supplemented with 2 mg l^-1 kinetin + 0.5 mg l^-1 NAA + 30 gl^-1 sucrose + 6 g l^-1 gelrite followed by in the medium supplemented with 1 mgl^-1 2ip + 30 g l^-1 sucrose + 6 g l^-1 gelrite (61% in cv. HKR-46 and 79.2 % in cv. HKR-126). Highly significant regeneration differences were observed in partially desiccated calli (48 h) in comparison to non-dehydrated (0 h desiccation) calli. Shoot regeneration frequency increased from 1.2 to 5.6 fold after 48 h of desiccation in both the cultivars on different regeneration media. Shoot regeneration frequency declined at 72 h desiccation treatment as compared to 48 h treatment. Well-developed plantlets were hardened and transferred to the green house.