Optimization of callus induction and plant regeneration from germinating seeds of sweet sorghum (Sorghum bicolor Moench)

An efficient regeneration system was developed using germinating seeds of two cultivars of sweet sorghum, Sorghum bicolor 'Yuantian No.1' and 'M81E', as explants. We tested different media supplements effects on callus induction. The effects of combinations of 2,4-D, KT, sucrose, agar and proline at different concentrations on callus induction were compared. While 'Yuantian No.1' seeds showed the highest embryogenic callus induction frequency (57%) on MS medium supplemented with 4 mg l-1 2,4-D, 0.2 mg l-1 KT, 0.6 g l-1 proline, 45 g l-1 sucrose and 0.8 g l-1 agar, 'M81E' seeds showed highest embryogenic callus induction frequency (74%) on MS medium supplemented with 4 mg l-1 2,4-D, 0.2 mg l-1 KT, 45 g l-1 sucrose and 1.2 g l-1 agar. The best shoot induction was observed when the explants were cultured on MS medium supplemented with 1 mg l-1 IAA and 3 mg l-1 6-BA, and on MS medium supplemented with 2 mg l-1 6-BA and 0.5 mg l-1 KT for 'Yuantian No.1' and 'M81E', respectively. The regenerated shoots were transferred onto MS medium supplemented with 3 mg l-1 IBA for rooting. After 2 weeks of culture, the percentage of root production was more than 85%. The plantlets were hardened on 1/2 MS medium and then transplanted to pots, where they exhibited morphologically normal growth.