Abstract:

【Objective】 The objective of this research was to establish a highly frequent and efficient regeneration system of sweet sorghum (Sorghum bicolor L. Moench), a kind of energy plants, so as to make preparation for genetic transformation.【Method】 The shoot apical meristems of sweet sorghum Keller were used as explants to investigate the effect of seedling age, phytohormone combinations and their ratios on the direct induction process of multiple shoots. Whether this regeneration pathway is less genotype-dependent in sweet sorghum, and whether the optimal culture method obtained above could be extended to other two genotypes, M-81E and Italian, were studied. 【Result】 It was easier to obtain a high meristem enlargement percentage using the shoot apical meristem from 3-day-old sterile seedlings as the explants. The optimal phytohormone combinations for multiple shoot induction of sweet sorghum were 4.0 mg?L-1 6-benzylaminopurine + 0.5 mg?L-1 2,4-dichlorophenoxyacetic acid + 0.5 mg?L-1 thidiazuron, in which 91% of multiple shoot induction could be achieved. Naphthaleneacetic acid at 0.5 mg?L-1 markedly increased rooting rate of multiple shoots. One explant with shoot meristem could be induced to produce above 100 multiple shoots, and finally 30–40 regenerated plants were produced through a directly-induced multiple shoot pathway. M-81E and Italian had a similar induction percentage and efficiency of multiple shoots as Keller. 【Conclusion】 A highly frequent and efficient regeneration system of sweet sorghum was successfully established, which has a sustainable explant supply, less genotype-dependence and good genetic stability.

Key words: sweet sorghum, shoot apical meristem, multiple shoots, genotype, a high frequency and efficiency regeneration system