橡胶树胶乳硫醇合成代谢过程中关键酶基因克隆、筛选及功能研究

Natural rubber is a raw material of high molecular compound with a widely use. The latex yield is mainly limited by duration of the latex flow.It is always a problem to increase duration of latex flow..The release of reactive oxygen is claimed to responsible for the peroxidative degradation of the lutoid membrane. Thiols ，which could delay latex coagulation， is an important antioxidant to laticifer sub-membrane , closely related to duration of late flow.Therefore，the pathway of thiols metabolism had been a research focus..In this study, the pre-research on genes clones in latex thiols anabolism pathway and analysis of metabolism product implied the presence of complete thiols synthesis pathway in laticifer. On that basis, key enzymes are:APR, GS, γ-ECS. The plan is genes cloning of key enzymes and studying their physiological function. The aims are ensuring the key gene and in-depth understanding the molecular regulation mechanism of thiols anabolism.

天然橡胶是一种用途广泛的天然高分子化合物。限制胶乳产量的因素之一是排胶持续时间，如何延长排胶持续时间一直是橡胶生产中的主要问题。.研究发现，割胶和排胶产生的大量活性氧使黄色体膜氧化破裂是导致胶乳凝固的主要原因。硫醇是乳管亚细胞膜的重要抗氧化剂，具有延迟胶乳凝固的作用，与排胶持续时间密切相关。因此，硫醇的代谢途径成为目前的研究热点。.本实验室通过硫醇合成酶基因克隆及其代谢产物分析等预研工作发现，橡胶树乳管中存在与模式植物类似的完整硫醇合成途径。在此基础上，发现关键酶包括APR、GS和γ-ECS；本研究将进一步克隆并鉴定其生理功能,预期明确硫醇合成的关键基因，深入理解其分子调控机制。

硫醇是乳管亚细胞膜的重要抗氧化剂，具有延迟胶乳凝固的作用，与排胶持续时间密切相关。本项目克隆得到14个橡胶树胶乳硫醇合成相关基因，证明胶乳中存在完整的硫醇合成途径；乙烯刺激引起胶乳硫醇含量有规律变化，综合分析品种之间和长流胶中基因表达情况，筛选得到Hbγ-ECS1和HbGS对于硫醇合成有重要作用。两个基因原核表达融合蛋白经过复性后证明有相应酶活，在植物中过量表达Hbγ-ECS1增加了70%植株叶片谷胱甘肽含量，过量表达HbGS增加了50%植株叶片谷胱甘肽含量。