【摘要】 棉子糖家族寡糖（RFOs）是高等植物中分布最广泛的含有半乳糖基（-Gol）的低聚糖。棉子糖（Raf）和水苏糖（Sta）是这一家族中的主要成员，在多种植物中作为渗透剂或活性氧清除剂维持细胞完整性。糖基水解酶36家族（GH36）是一类α-半乳糖苷酶，能够催化含-Gol的寡糖生成RFOs。巴西橡胶树（Hevea brasiliensis）是合成天然橡胶的重要植物，割胶和外源乙烯刺激后，胶乳中糖基水解酶大量积累，在维持胶乳稳定性方面具有重要作用。为了寻找巴西橡胶树胶乳中的功能水解酶，本研究成功鉴定糖基水解酶36家族（HbGH36）的8个基因（HbGH36-1～8）。qRT-PCR分析显示，5个基因（HbGH36-1、HbGH36-4、HbGH36-6、HbGH36-7、HbGH36-8）在乳胶中显著表达。其中，HbGH36-4、HbGH36-6、HbGH36-7和HbGH36-8在割胶刺激下呈高水平表达，尤以HbGH36-4和HbGH36-7的表达变化最为显著。此外，HbGH36-1、HbGH36-4、HbGH36-6和HbGH36-7在外源乙烯处理下也表现出高水平表达，而HbGH36-6在乙烯诱导后维持高水平表达的时间相对更长。巴西橡胶树胶乳不同组分的Western Blot证实，HbGH36-1和HbGH36-8的表达产物在胶乳的C乳清组分中高水平积累。这些结果表明巴西橡胶树HbGH36s可能参与了排胶过程中胶乳稳定性维持及割胶、乙烯刺激后的胶乳生理代谢调控。更多还原

【Abstract】 Raffinose family oligosaccharides(RFOs) are the most widely distributed oligosaccharides containing galactose(-Gol) in higher plants. Raffinose(Raf) and stachyose(Sta) are the main members of this family, which are used as osmotic agents or active oxygen scavengers in many plants to maintain cell integrity. Glycosyl hydrolase 36 family(GH36) is a kind of α-galactosidase, which can catalyze oligosaccharides containing-Gol to produce RFOs. Hevea brasiliensis is an important plant for synthesizing natural rubber. After tapping and stimulation by exogenous ethylene, glycosyl hydrolases accumulate in latex and play an important role in maintaining latex stability. Eight genes(HbGH36-1-8) of glycosyl hydrolase 36 family(HbGH36) were successfully identified to search for functional hydrolases in the latex of H. brasiliensis. QRT-PCR analysis showed that five genes(HbGH36-1, HbGH36-4, HbGH36-6, HbGH36-7, HbGH36-8) were obviously expressed in latex. Among the five genes, HbGH36-4, HbGH36-6, HbGH36-7 and HbGH36-8 were highly expressed in response to tapping stimulation, and the expression levels of HbGH36-4 and HbGH36-7 changed more obviously. HbGH36-1, HbGH36-4, HbGH36-6 and HbGH36-7 expressed at high levels in response to exogenous ethylene stimulation, and HbGH36-6 expressed at high levels for a relatively long time after ethylene stimulation. Western blot of different components of H. brasiliensis latex confirmed that HbGH36-1 and HbGH36-8 were expressed in C-serum component of latex. The results indicate that H. brasiliensis HbGH36s may be involved in the regulation of latex stability and latex physiological metabolism in response to tapping and ethylene stimulation.更多还原