红光提高西瓜南方根结线虫抗性的分子机制研究

Being a major root-knot nematode, Meloidogyne incognita remarkably affects watermelon (Citrullus lanatus) production by minimizing its yield. We proved that red light significantly enhances plant resistance against root knot nematodes; however, the underlying molecular mechanisms are largely unclear. Hence, the proposed project intends to elucidate in-depth mechanisms of red light-induced systemic acquired resistance through investigating the mRNA expression, miRNA expression and proteomic profile in leaf, phloem sap and root using RNA-seq and iTRAQ in watermelon (member of cucurbitaceae family). Furthermore, an attempt will be taken to establish correlation among data from various platforms (mRNA, miRNA expression and proteomic profile) and different plants tissues to reveal a comprehensive picture of red light-promoted plant defense resistance mechanisms. Thus, this project will shed much light to the molecular mechanisms of red light-induced resistance to root knot nematodes particularly at transcriptional, post-transcriptional and protein levels, to develop an environment-friendly pest management strategy for improving yield and quality of watermelon.

根结线虫病严重影响西瓜的产量。我们研究发现红光显著提高作物对南方根结线虫的抗性，但其中所涉及的抗性信号长距离传导，及其诱导作物抗性的分子机制尚不清楚。本项目拟以红光处理叶片和根部接种南方根结线虫为模式系统，以西瓜为材料，采用 RNA-seq（定量）、小RNA高通量测序与蛋白质组同位素标记相对和绝对定量（iTRAQ）技术，比较红光诱导接种南方根结线虫西瓜叶片、韧皮部和根部的差异表达mRNA、miRNA和蛋白质组，并对RNA-seq（定量）和小RNA测序数据、RNA-seq（定量）和蛋白组数据进行关联分析，分析叶片-韧皮部-根部的长距离运输信号在提高根部抗性中的作用机制，及基因表达调控的转录、转录后和翻译水平间的相互关系，筛选出红光诱导西瓜抗南方根结线虫的关键基因。阐明红光提高西瓜对南方根结线虫抗性的分子机制，为环境友好型利用红光减轻根结线虫的危害，提高西瓜的产量和品质提供理论基础和实践指导。

根结线虫已经成为限制西瓜生产发展的重要病害，在设施内补红光诱导西瓜自身的抗性从而减轻根结线虫的危害，为保障西瓜产量、品质和经济效益提供新的途径。本项目研究发现红光激活茉莉酸和水杨酸途径、增加抗氧化酶活性以及调控细胞氧化还原平衡从而减轻南方根结线虫对西瓜的危害。基于RNA-Seq测序、小RNA测序和蛋白质组测序定量分析技术，我们发现红光主要通过诱导茉莉酸/乙烯途径基因、活性氧以及MAPK相关基因在转录水平、转录后水平和翻译水平的差异表达，并通过韧皮部传输到根部，诱导根部茉莉酸及抗氧化酶途径基因、miRNA和蛋白质水平的上调表达，促进根部的茉莉酸含量和抗氧化酶的增加，从而减轻根结线虫对西瓜的危害。进一步的研究发现红光诱导西瓜叶片和根部的茉莉酸合成途径基因AOC2和LOX4基因的上调表达，促进茉莉酸含量的增加从而增强西瓜对根结线虫的抗性。本项目揭示了红光诱导西瓜系统性抗性减轻南方根结线虫危害的信号转导机制，为通过遗传改良西瓜抗性提供了重要的候选基因，以及为利用LED灯补红光诱导西瓜对根结线虫的抗性提供了理论依据和实践指导。