| Picea Likiangensis is the only species of Picea distributed in Yunnan. Taking its zygoticembryos as explants, somatic embryogenesis was carried out with induced embryogenic callusas experimental material. Exogenous glutathione (GSH) with20mg·L-1was added into matureculture mediums, As a comparison with blank. The contents of soluble proteinand soluble suger,glutathione reductase activities involved in glutathione metabolism and superoxide dismutaseactivities in different development stages were determined. One-way analysis of variance andmulti-comparison were carried out to analyze the results. The research will lay a foundation forfurther study on Physiological and biochemical mechanism of somatic embryogenesis in otherconifers. The main results are showed as followings:(1) Morphological observations were conducted on calli and somatic embryos atdevelopmental stages.Somatic embryogenesis underwent three main period：proembryos mass,globular embryo and cotyledonary embryo in Picea Likiangensis. Compared with theircounterpart,morphological characteristics of GSH-treated embryos were not different.(2) Soluble protein content was2.65mg g-1in embryogenic callus. Soluble proteincontent of globular embryo and cotyledonary embryo were47.49mg·g~-1and34.83mg·g~-1respectively. They were higher17-and12-fold than that of callus. The soluble protein contentsin globular and cotyledonary embryo treated with GSH were42.27mg·g-1and30.46mg·g-1.The embryos treated with GSH showed a lower contents of protein than the control,whichwere no significant differences. The results showed that there are both cell division anddifferentiation during globular embryos period, along with active metabolism, vigorous growthand a high level of protein contents. physiological maturation of the embryos can be inhibitedby glutathione.(3) The soluble suger contents increase from0.57%in embryogenic callus to6.36%inglobular embryo during somatic embryogenesis of Picea Likiangensis, and decrease duringcotyledonary embryo period. Soluble suger content of cotyledonary embryo was only2.31%. Soluble suger content of globular and cotyledonary embryo treated with GSH were7.07%and3.03%reseparately.There were significant differences between check and treatment. Theanalysis indicated that GSH can promote synthesize of the soluble suger during embryogenesis.(4) SOD activity of embryogenic callus was only43.16U/g. SOD activity was up to465.09U/g in globular embryo,which fell rapidly in cotyledonary embryo with.42.96U/g.Differences were very Significant. A concentration of20mg·L-1GSH led a decrease of SODactivities,which were not significant differences. These results showed that SOD activity canbe inhibited by exogenous GSH.(5) GR activity was about4.98mmol min~-1mg~-1pro. in embryogenic callus. GR activityof globular embryo and cotyledonary embryo was very lower, which were0.46and0.36mmol·min-1·mg-1·pro. separately. There were significant differences. GR activity of the grouptreated with GSH were both higher than those of control group. There were not significantdifferences in globular embryo and cotyledonary embryo. It is indicated that effects of GSH onembryogenesis is complicated. GSH could be regulate the cell oxidation-reduction state andalso participate GSH-catalyzed reaction.The results showed that mature phase of somatic embryo development is active stage ofmetabolic process. Globular embryo phase is crucial for somatic embryogenesis with high levelof protein,soluble suger and SOD activity. Exogenous glutathione can promote sugaraccumulation but inhibit the protein synthesis of somatic embryo in Picea Likiangensis.Simultaneously, which also improve the GR activity and reduce the SOD activity. This researchnot only lain a good foundation for the further application of the technology of somaticembryogensis in trees, but also provided important basis for solving the problems of lifesciences. |
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