Optimizing the Protocol for In vitro Regeneration through Callus in Rice Varieties, viz; Ratnagiri-8, Karjat Shatabdi and Karjat-3

The investigation entitled “In vitro regeneration studies in rice (Oryza sativa L.)” was carried out in tissue culture laboratory at Plant Biotechnology Centre, College of Agriculture, Dapoli-Ratnagiri (M.H.) in Completely Randomized Design with 3 replications. The aim of the research was to set up the in vitro regeneration protocol in the three rice varieties, viz, Ratnagiri-8, Karjat Shatabdi, Karjat-3 with an objective to investigate suitable callus induction medium and develop an efficient regeneration technique for genetic transformation. Mature seed embryo was used as explant for callus initiation. The callusing ability of the varieties was tested on 12 medium combinations with different concentrations of 2,4-D and NAA, their combinations and one control treatment. Medium combination T2: MS + 2,4-D (2.0 mg/l) + NAA (0.5 mg/l) gave the highest callus induction in Ratnagiri-8 and Karjat Shatabdi with a callus induction frequency of 66.67 % and 53.33 % respectively and callus weight of 0.367 g and 0.290 g respectively. Karjat-3 showed highest callus induction for medium combination T3: MS + 2,4-D (2.0 mg/l) +NAA (1.0 mg/l) with a callus induction frequency of 68.33 % and callus weight of 0.392 g. Embryogenic, soft, friable callus with granular texture and yellowish white colour was obtained from all media combinations in all three varieties. The regeneration ability of the varieties was tested on 15 medium combinations with different concentrations of BAP and Kinetin, their combinations and one control treatment. The shoot and root induction was obtained on same medium. The highest regeneration was observed for T5: MS + BAP (2.5 mg/l) in Ratnagiri-8 and Karjat Shatabdi with a shoot induction frequency of 83.33% and 73.67% respectively and root induction frequency of 76.33% and 64.67% respectively. In Karjat-3, highest regeneration was observed for T6: MS + BAP (3.0 mg/l) with a shoot and root induction frequency of 78.33% and 69.00% respectively.