Rapid callogenesis and plant regeneration of fine and coarse varieties of rice

In this study, we aimed to develop an effective and genotype-dependent protocol for in vitro callogenesis and plant regeneration of two fine rice varieties (Super Basmati and Basmati-515) and one coarse variety (KS-282). According to the results, maximum callus induction (52% of the explants) was observed in case of KS-282 after 11 days of incubation with Murashige and Skoog basal medium (MS, with 30 g/l sucrose and 1.76 g/l Gellan gum), which was supplemented with 3 mg/l of 2,4-dichlorophenoxy acetic acid (2,4-D). In contrast, 41% of the Super Basmati explants produced callus within 17 days, followed by 32% of the Basmati-515 explants (within 11 days), in the aforementioned medium but which is supplemented with 4 mg/l 2,4-D. Indirect shoot formation from callus was found to be the highest in case of KS-282 (24% of callus explants) and Basmati-515 (18% of callus explants) after 21 days of incubation. Next, we tested MS medium without 2,4-D but which was supplemented with 3 mg/l kinetin (Kin), 1 mg/l 6-benzyladenine (BA), and 0.5 mg/l indole-3-acetic acid (IAA). According to the results, 22% of the explants of Super Basmati formed shoots after 19 days on MS medium supplemented with BA instead of 2,4-D at a concentration of 1 mg/l. Roots were formed from shoots on a half-strength MS medium without plant growth regulators after 15 days in KS-282 (93% roots formed), after 19 days in Super Basmati (90% roots formed), and after 23 days in Basmati-515 (86% roots formed). Shoots were effectively multiplied in KS-282, followed by Super Basmati, and Basmati-515 varieties (37, 29, and 23 shoots/shoot, respectively) on a basal MS medium supplemented with 4 mg/l Kin. Rooting was induced within 47, 55, and 57 days for KS-282, Super Basmati, and Basmati-515, respectively. Following acclimatization, the percentage of survival was found to be 71%, 70%, and 65%, which was found to be at-par for all three tested rice varieties.