小橡胶粒子膜蛋白异构体翻译后修饰在激素刺激橡胶生物合成中的调控机制

Plant hormone (ethylene and jasmonate) can activate the natural rubber biosynthesis and sharply improve natural rubber production, which has been proved by many studies and widely used in natural rubber production all over the world. However, it is a long enigma that many genes involved in rubber biosynthesis were not induced upon exogenous hormone treatment. Based on our proteomics results for rubber latex and rubber particles and several recent reports, we bring forward an assumption that ethylene and jasmonate can improve natural rubber biosynthesis by inducing the post-translational modifications of some isoforms of small rubber particle protein (SRPP). The hormonal regulation of natural rubber biosynthesis is not mainly based on gene expression, but on protein level, in particular on post-translational modifications of some specific protein isoforms. We think the phosphorylation, glycosylation and ubiquitination of SRPP isoforms play crucial roles on hormone-stimuli of natural rubber biosynthesis. Therefore, in this project, our first object was set to identify as many as SRPP isoforms from latex and rubber particles, then determine their exact post-translational modifications by using proteomics and molecular biology technologies. After that, we plan to verify their detail biological functions and changed patterns on ethylene and jasmonate stimulation. These results will basically clarify the potential roles of phosphorylation, glycosylation and ubiquitination of SRPP isoforms on natural rubber biosynthesis and deepen our understanding of the basic molecular mechanisms of the increasing latex yield which produce by hormone stimuli. These results will also reveal a new regulation mechanism of ethylene and jasmonic acids on natural rubber biosynthesis, and provide a new theoretical foundation for reasonable utilization of plant hormone to stimulate natural rubber latex production in future.

天然橡胶生产实践及以往研究证实，植物激素（乙烯和茉莉酸）刺激能提高橡胶生物合成效率和胶乳产量，但并不诱导甚至抑制橡胶合成中关键基因表达，这是长期困扰橡胶生物合成研究的一个谜。根据前期蛋白质组结果及最新发表的资料，我们认为激素调控橡胶合成并不在基因水平，而是在蛋白质特别是蛋白翻译后修饰水平，橡胶合成关键酶的磷酸化、糖基化和泛素化起重要作用，其中小橡胶粒子膜蛋白（SRPP）不同异构体的翻译后修饰很可能是橡胶合成调控的关键开关。本项目采用蛋白质组学和蛋白质化学等技术，从经乙烯和茉莉酸处理前后的胶乳和橡胶粒子膜中鉴定SRPP的不同异构体并检测修饰位点，分离纯化不同异构体，比较修饰前后不同异构体对橡胶合成效率的影响，并对其功能进行体外验证。研究结果有助于阐明SRPP不同异构体的翻译后修饰在植物激素乙烯和茉莉酸调控天然橡胶生物合成中的作用方式，为深入理解橡胶生物合成调控新机制提供新的理论依据。

天然橡胶生产实践及以往研究证实，外施乙烯能极显著提高天然橡胶胶乳产量，但并不诱导甚至抑制橡胶合成中关键基因表达，这是长期困扰橡胶生物合成研究的一个谜。根据前期蛋白质组结果及最新发表的资料，我们认为乙烯调控橡胶合成并不在基因水平，而是在蛋白质特别是蛋白翻译后修饰水平，橡胶合成关键酶的磷酸化、糖基化和泛素化起重要作用，其中小橡胶粒子膜蛋白（SRPP）不同异构体的翻译后修饰很可能是橡胶合成调控的关键开关。本项目采用蛋白质组学和蛋白质化学等技术，从经乙烯处理前后的胶乳和橡胶粒子膜中鉴定SRPP的不同异构体并检测修饰位点，分离纯化不同异构体，比较修饰前后不同异构体对橡胶合成效率的影响，并对其功能进行体外验证。最终，我们构建了乙烯通过调控小橡胶粒子上关键蛋白质异构体磷酸化修饰来促进橡胶生物合成的调控模式图，发现了乙烯刺激割胶的调控新机制，为深入理解橡胶生物合成提供新的理论基础。