Effects of polyamines on organogenesis and somatic embryogenesis of Lycium barbarum calli.

Levels of three endogenous free polyamines (PAs), Put, Spd and Spm, were detected during organogenesis and somatic embryogenesis (SE) of Lycium barabrum (L.) calli. The predominant forms of PAs in organogenesis and SE were found to be Put and Spd, respectively. In both developmental pathways, the changes of Put content were very similar, i.e., it accumulated quickly in the initial stages of calli differentiation and then decreased; with the further morphogenesis, increase in Put level was also observed. The highest level of Spd was obtained at day 1 of calli organogenesis; while, after 1 day of culture for calli SE, Spd level began to increase and reached a maximum at day 10. The treatments with exogenous PAs had positive effects on both organogenesis and SE, especially those of Spd on organogenesis and SE and Put on SE. However, Put showed no effects on adventitious bud formation. CHA, which inhibits the activity of Spd synthetase, prevented both adventitious bud formation and further development of somatic embryo into plantlet. Although MGBG, a specific inhibitor of S-adenosyl methionine decarboxylases, had little effects on organogenesis, it reduced the number of somatic embryo and the plantlets subsequently regenerated. Such inhibitions could be reversed by Spd (50 mumol/L). These results from organogenesis and SE of the same specie indicate that PAs influenced these two in vitro morphogenesis pathways.