苜蓿体细胞胚胎发生过程中DNA、RNA和蛋白质的合成动态

苜蓿(Medicago sativa L.)下胚轴切段产生的愈伤组织经2,4-D短时间诱导后,在无激素液体培养基中可形成大量体细胞胚胎。经2,4-D诱导后的愈伤组织在转入无激素培养基1天后,其DNA、RNA和蛋白质的合成即进入活跃合成状态,并在体细胞胚胎发育过程中保持逐步升高的趋势。在苜蓿体细胞胚胎发生过程中,有些蛋白质组分含量减少或消失,但绝大部分蛋白质组分的含量明显增加,并且有若干新蛋白的出现,其中24 KD和46 KD蛋白质为体细胞胚胎发生早期所特有。

CHANGES IN THE SYNTHESES OF DNA, RNA AND PROTEIN DURING SOMATIC EMBRYOGENESIS IN ALFALFA (Medicago sativa L.)

The activities of DNA, RNA and protein syntheses during somatic embryogenesis of alfalfa (Medicago sativa L.) were investigated. Callus formed from hypocotyl explants was dispersed in liquid suspension medium in the presence of 8.0 mg/L 2,4-D for 3 days. Then, the cell suspension was subcultured in hormone-free liquid medium and a large number of somatic embryos appeared after 15-20 days of culture. By pulse incorporation of ~3H-thymidine, ~3H-uridine and ~3H-leucine into DNA, RNA and protein respectively, the rates of syntheses of DNA, RNA and protein were measured. After 2,4-D induction,the synthese of DNA, RNA and protein increased rapidly and showed a trend of gradual increase during somatic embryogenesis. Total soluble proteins were extracted fro m embryogenic and non-embryogenic calli and were analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF)/SDS-PAGE two dimensional electrophoreses. The results demonstrated that many preexisting proteins increased and some were newly synthesized during somatic embryogenesis. Two polypeptides of 46 KD and 24 KD were specific to the early stage of somatic embryogenesis.