采后哈密瓜对曲霉病原菌侵染的分子应答机制研究

Hami melon is characteristic amphisarca in Xinjiang, postharvest melon is highly infected by pathogen during storage and transportation.Understanding and regulation of mechanism of postharvest Hami melon response to the pathogenic microorganism infection is the key for improving storage quality and prolonging the storage time. The project prepares to study postharvest Hami melon response to the pathogenic microorganism infection using proteomics, transcriptomics, bioinformatics technology, etc. The variation of microscopic structure, physiologic and biochemical index, proteome and differential gene expression on transcription level in Hami melon are investigated thoroughly, before and afte they are infected by the pathogenic microorganism.The major differential pathogenesis-related protein is identified preliminarily, then its main function and quantity are analysed. We will reveal the type, function and quantity of the different expression gene, and verify the relevance among differential protein, different expression gene and infection process.The results will help us to find and identify the important pathogenesis-related differential protein and gene, clarify the mechanism of postharvest Hami melon response to Aspergillus pathogenic microorganism infection on the mRNA and protein expression level,and establish a foundation for expression and regulation of disease resistance related gene, then provide the theory basis for no pollution control and green fresh-keeping technology for postharvest Hami melon.

哈密瓜是新疆特色瓜果，贮运过程中极易受到病原菌的侵染，采后哈密瓜应对病原菌侵染的反应机制的理解和调控是提高其贮藏品质和延长贮藏时间的关键。本项目拟采用蛋白质组学、转录组学及现代分子生物信息学等技术手段，研究采后哈密瓜对曲霉病原菌侵染的应答反应，深入考察曲霉病原菌侵染前后哈密瓜微观结构、生理生化、果实总蛋白质组、基因转录组水平的差异变化；初步鉴定与病程相关的重要差异蛋白质，分析其主要功能作用；揭示曲霉侵染过程中哈密瓜差异表达基因种类、功能和数量，明确差异蛋白、差异表达基因与曲霉侵染过程的关联性。项目研究结果将有助于发现并鉴定与哈密瓜抗病性相关的重要差异蛋白质和基因；从mRNA和蛋白质的表达水平阐明采后哈密瓜对曲霉病原菌侵染的应答机制，为开展相关抗病性基因的表达调控奠定基础，进而为哈密瓜采后病害的无污染防治技术和绿色保鲜技术，提供理论依据。

果实对病原菌侵染的响应机制明晰是哈密瓜腐烂控制技术研究的关键科学问题之一。本项目通过病原菌侵染前后哈密瓜果实超微结构、抗性酶活性变化研究；差异表达基因、差异蛋白组学分析等，较为深入的揭示了哈密瓜果实对霉菌侵染的应答机制，研究结果表明：.1、对霉菌侵染前后哈密瓜差异表达基因进行筛选，处理48小时具有差异表达基因15089个（上调7489，下调7600），处理60小时具有差异表达基因14545个（上调6699，下调7846）。进一步分析表明，哈密瓜果实可以通过谷胱甘肽代谢，油菜素甾醇（BRs）、水杨酸信号等途径中关键基因的表达调控响应霉菌的侵染。.2、采后哈密瓜可以通过调节钙依赖蛋白激酶、钙调蛋白等基因表达产生过敏反应；通过调控延长因子Tu、细胞分裂素激活蛋白激酶1等诱导病程相关蛋白（PR1）上调表达，提高对青霉菌的抗病性。.3、对霉菌侵染前后哈密瓜果实蛋白进行鉴定分析，获得了4855个果实表达蛋白，其中包括76个未知功能蛋白。进一步分析可知，在霉菌侵染60小时持续发挥抗性作用的有内切几丁质酶MCHT-2、过氧化物酶52；在霉菌侵染48小时起到重要抗性作用的有谷胱甘肽S转移酶PARB、酸性内切几丁质酶等。.4、荧光定量PCR表明，哈密瓜受到霉菌侵染后，HmCHI基因的表达量持续上升，在60小时达到最大值。HmCDPK1和HmCDPK2对于病原菌侵染的响应主要发生在胁迫前期，在6h左右到达峰值。适当的浸钙处理可以提高HmCDPK1和HmCDPK2表达量。.本研究结果有助于揭示哈密瓜对霉菌侵染的应答机制，为采后哈密瓜开展相关抗性基因和蛋白的表达调控奠定基础，进而为哈密瓜采后病害的无污染防治技术和绿色保鲜技术提供理论依据。