植物microRNA (miRNA)是一类长度约20-24 nt的小分子RNA，对靶标mRNA进行剪切或抑制翻译，从而实现对靶基因的调控。miRNA在植物的生长发育、抗逆反应等方面起着重要作用。西瓜嫁接能够提高其养分吸收利用效率，但其作用机理尚未阐明。本项目以西瓜自根和异源嫁接体系为对象，基于西瓜高通量测序数据，鉴定嫁接后与低氮、低磷胁迫相关的miRNAs和靶基因，研究低氮、低磷胁迫条件下，嫁接后miRNA及靶基因对上述逆境的调控作用。此外，鉴定可能作为长距离信号分子在韧皮部运输的miRNA及其特性。本项目试图阐明miRNA在嫁接体系中调控西瓜对氮、磷养分高效吸收和利用的作用机制，验证miRNA作为长距离运输信号在地上部-地下部反馈交流系统中的作用机制，最终揭示miRNA介导的嫁接调控西瓜对氮、磷响应的分子机制。

Micro RNAs (miRNAs) are a specialized class of small endogenous RNAs with length of approximate 20 - 24 nt in plants. MiRNAs control the expression of target genes by binding to reverse complementary sequences, resulting in cleavage or translational inhibition of the target mRNAs. MiRNAs have been shown to play a critical role in plant growth, development and stresses response.Grafting enhances its nutrition absorption and utilization efficiency and adaptation to abiotic stresses.However,the mechanism is largely unknown.In this project, we are trying to identify the miRNAs and their targets in watermelon grafting system in response to low nitrogen and low phosphorus stresses based on high-throughput sequencing and degradome sequencing. We try to study how the specific miRNAs and their targets response to low nitrogen and low phosphorus stresses in grafting system. Also,we want to investigate the potential signalling role of miRNAs in phloem as the long-distance feedback regulation signaling in grafted watermelon.The aim of our project is to reveal the miRNA-mediated regulatory networks involved in the grafting system that improves the nitrogen and phosphorus absorption and utilization efficiency.