基于高通量测序研究microRNA调控嫁接西瓜氮、磷养分吸收和利用的分子机制

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.

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。

植物microRNA (miRNA)是一类长度约20-24 nt的小分子RNA，在植物的生长发育、抗逆反应等方面起着重要作用。它们通过对靶标mRNA进行剪切或抑制翻译，实现对靶基因的调控。瓜类作物嫁接可提高其抗逆性和养分吸收利用效率，但其作用机理尚未阐明。本项目基于高通量测序技术，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及靶基因对上述低氮、低磷逆境胁迫的调控作用。通过本项目实施，我们系统分析了不同嫁接情况下砧木和接穗间的miRNA和mRNA变化，发现了大量嫁接可移动或诱导表达的miRNA及其相应靶基因；筛选了数个在嫁接和氮磷养分等复杂条件下稳定表达的内参miRNA；明确了两个新葫芦科miRNA (ClmiR86 和 ClmiR84) 受到嫁接调控或通过嫁接在接穗-砧木间移动，从而通过下游靶基因(CIPK和bHLH)分别正向或负向调控嫁接西瓜的低磷胁迫响应以及磷元素吸收利用。综上，本项目初步验证了部分miRNA作为长距离运输信号在地上部-地下部反馈交流系统中发挥功能，并且介导了嫁接调控西瓜对低氮、低磷胁迫响应。为最终揭示嫁接调控瓜类蔬菜养分吸收利用的分子机制及调控网络提供重要理论基础。