γ- - 氨基丁酸对果实采后抗病性的诱导规律及其作用机制研究

The control of postharvest decay by using induced resistance, as a safe and environment-friendly novel means, has become a promising non-fungicidal approaches in recent years. However, induced resistance is plagued by inconsistency and relatively poor disease control compared with pesticides. Therefore, there is an increased need to explore the limited factors of induced resistance and stimulated demand for more selective, safer, resistance-breaking, cost-effective activators. Recent studies have shown that γ-aminobutyric acid (GABA) plays key roles in plant defense, however, there is little information about the effect of GABA on the postharvest fungal diseases of fruit. In order to explore the role and the regulation mechanisms of GABA in the induction of resistance in harvested fruit, this study was designed to investigate the effect of GABA on inducing resistance against fruit diseases, and to analyze the relationship between the GABA metabolism (glutamate decarboxylase, Succinic semialdehyde dehydrogenase, γ-aminobutyrate transaminase) and induced resistance against fungal diseases, and to examine the transcriptome and metabolome of fruits reposing to GABA and pathogen at the molecular level. and to compare the proteomic profile of fruit under GABA and fungal pathogens by LC-MS/MS so as to analysis of the relationship between GABA branch and TCA cycle, and the correlation between GABA branch and the metabolism fruit resistance, aging and quality related. The results of this study will provide the new and fundamental information on the molecular mechanisms by which GABA controls the postharvest diseases and for development of new activators.

利用激发子诱导果实抗性是一个有效抑制采后病害的方法，但现有的诱导剂的效力和稳定性等与杀菌剂相比还存在很大的差距。γ-氨基丁酸 （γ-aminobutyric acid，GABA）在植物抗性中具有关键作用，但其对果实采后病害的影响尚未见报道。本项目拟在前期研究的基础上，进一步分析GABA对果实抗性诱导的规律及主要影响因素；对果实中GABA代谢和抗性等相关代谢进行系统检测；利用GC-MS、RNA-Seq，iTRAQ和LC-MS/MS、生物信息学技术等系统观测GABA处理后果实在物质、基因和蛋白组等层面上的表达模式和所涉及的信号网络，探索揭示GABA支路与TCA循环等主代谢，与果实抗性、衰老和品质等相关代谢的关系，从而系统分析与GABA相关的生理代谢途径及其调控机制。研究结果将为明确GABA诱导果实抗性的分子机理，以及为开展定向提高果实抗性诱导效力的研究，开发新型、绿色抗病保鲜剂提供基础信息。

γ-氨基丁酸 （γ-aminobutyric acid，GABA）广泛存在于生物体中，具有多种重要的生理功能，并且是国家批准的新食品原料。为系统研究GABA对果实抗性诱导的规律和生物学机理，本项目对GABA诱导果实病害抗性的规律及主要影响因素、GABA对果实抗病性诱导所涉及的主要代谢途径和果实体内GABA代谢对外源诱导抗性剂的响应规律及与抗性的相关性等进行了研究，取得的主要结果如下：（1）GABA及其前体L-谷氨酸（Glu）在较低的浓度（10-100ppm）就能显著诱导梨、番茄、柑橘等多种果实对扩展青霉、灰葡萄孢和链格孢等多种真菌侵染的抗性，其效力与所使用的浓度、处理时间、病原菌浓度等因素密切相关；并明确了温度等环境条件、氢离子和钙离子、GABA和谷氨酸代谢抑制剂对GABA/Glu诱抗活性的影响；（2）通过对果实抗性生理、抗性基因表达的测定，并结合第二代测序技术、iTRAQ技术、GC-MS技术、生物信息学技术分析和氨基酸分析仪等的分析和电镜观察，在超微结构、基因转录、蛋白表达和物质代谢等多个角度探索明确了GABA /Glu诱导果实抗性的机理与其调节果实体内的GABA支路、谷氨酸及氨基酸代谢、能量代谢、生长素、水杨酸合成和信号转导通路、活性氧代谢和苯丙烷次生代谢等密切相关，并可能存在PRIMING机制；而与茉莉酸/乙烯信号通路也有一定的相关性；（3）通过比较GABA与Glu、IAA、酵母细胞壁及其提取物等生物型激发子对果实抗性生理、基因转录、蛋白表达和物质代谢等影响，进一步明确了果实体内的GABA支路及谷氨酸在果实抗性形成和对病原菌的响应中具有重要作用。研究成果为进一步分析GABA及相关物质和相关代谢在果实抗病性调控中的作用提供了基础，并对开发基于GABA及相关物质活性的新型、绿色诱抗剂提供了理论依据。