BA和NAA对水曲柳(Fraxinus mandshurica)未成熟胚子叶外植体褐化及体胚发生的影响

为了解析植物生长调节剂与水曲柳体细胞胚胎发生普遍伴随外植体褐化现象的关系,本研究以水曲柳未成熟合子胚子叶为外植体进行体胚发生,对细胞分裂素BA和生长素NAA的影响效应进行了探讨。结果表明,(1)当培养基中添加0.5mg/LBA和1.5mg/LNAA时,产生体胚的外植体褐化率达到91.5%;褐化外植体的体胚发生率达50.8%,而未褐化外植体的体胚发生率仅为9.6%;(2)添加NAA是水曲柳未成熟合子胚子叶外植体褐化的充分必要条件,即:无NAA存在时,未成熟合子胚子叶外植体不发生褐化,有NAA存在时才会发生褐化;只添加NAA外植体会产生褐化,但褐化程度低于同时添加BA,说明BA是促进褐化的条件;(3)添加NAA与BA是水曲柳未成熟合子胚外植体发生体胚的必要条件,即不添加生长素和细胞分裂素时无体胚发生;(4)NAA与BA的交互作用对褐化率的影响差异显著,但对体胚发生率的影响差异不显著,说明BA和NAA处理对外植体褐化的作用与对体胚发生的作用不同。由此可知:水曲柳未成熟合子胚子叶外植体的褐化和体细胞胚胎发生均受细胞分裂素BA和生长素NAA的影响,但BA和NAA分别调控了外植体的褐化和体胚的发生,与二者伴随的现象没有关系。本研究结果对进一步深入解析水曲柳体胚发生伴随外植体褐化的生物学机理提供了科学依据。

Effects of BA and NAA on Explant Browning and SE from Immature Zygotic Cotyledon of Fraxinus mandshurica

Somatic embryogenesis of Fraxinus mandshurica and the effect of cytokinin BA and auxin NAA were studied by using young zygotic cotyledons as explants for the purpose of explicating the relationship between plant growth regulators and the phenomenon of which somatic embryogenesis of F. mandshurica is accompanied by its explant browning. The results were as follows:(1) Treated with BA 0.5 mg/L and NAA 1.5 mg/L, 91.5% of the explants that regenerated somatic embryo(SE) was browned;otherwise, the conduction rate of SE of the browning explants reached 50.8%, whereas the nonbrowned explants was just 9.6%;(2) NAA was the necessary and sufficient conditions for zygotic cotyledon explant browning of F. mandshurica, i.e. the browning was just able to occur after adding NAA into the SE induction medium;in case of NAA added, the explant browning was in a weak state if there was no BA addition at the same time but heavy after BA was added at the same time, which was indicated that BA was just the necessary condition for promoting explant browning;(3) NAA and BA were the necessary and sufficient conditions for SE induction from zygotic cotyledon explants of F. mandshurica, i.e. the SE was just able to occur after adding NAA and BA into the SE induction medium together;(4) The treatments of different concentrations of NAA and BA had significant influence on explant browning but no significant influence on SE induction,this indicated that there was no consequent relationship for the effects of NAA and BA on explant browning and SE induction. Conclusion: BA and NAA had the significant influence to the explant browning and somatic embryogenesis from immature zygotic cotyledon explants of F. mandshurica, but they regulated explant browning and somatic embryogenesis respectively, i.e. there was no relationship between the plant growth regulation influence and the accompanying phenomenon. This result provided a basis of further biological mechanism analysis of the accompanying phenomenon of explant browning and somatic embryogenesis.