miR159/319调控嫁接西瓜低温抗性的信号传导分子机制

Grafting can effectively improve horticultural plant tolerance to stresses such as cold, but the underlying mechanism still remains obscure. MicroRNA (miRNA) plays an important role in regulating plant tolerance to stresses such as cold. The applicant has discovered that miR159/319 participates in grafting regulation of watermelon tolerance to cold stress. Thus, the applicant proposes that tolerant rootstock regulates the expression of scion miR159/319 via long-distance signaling and miR159/319 regulates scion tolerance against cold stress by interacting with cold responsive signals. Grafted watermelon as material and technologies such as genetic transformation, qRT-PCR, enzyme linked immunosorbent assay, and laser confocal will be used in this project. The project intends to identify the long-distance signal(s) mediated regulation of scion miR159/319 by rootstock and the underlying signal transduction pathway by examining the transport of candidate signaling molecules from root to shoot and changes in miR159/319 and target genes as influenced by candidate signaling molecules. To get further detail of downstream signal transduction of miR159/319, the changes in signaling cascades and key gene expression as influenced by miR159/319 and target gene overexpression will be analyzed. The project aims at elucidating the molecular mechanism of miR159/319 in regulating grafted watermelon tolerance to cold stress and will provide theoretical direction for regulation of plant tolerance to stresses.

嫁接是提高园艺作物低温等逆境抗性的有效手段，但其机理尚不清楚。MicroRNA（miRNA）在植物抵御低温等逆境中起重要的调控作用。申请者研究发现miR159/319在嫁接提高西瓜低温抗性中发挥重要的调控作用，因而提出抗性砧木通过长距离信号调控接穗miR159/319的表达，miR159/319与低温响应信号互作调控接穗的低温抗性。本项目拟以嫁接西瓜为材料，利用遗传转化、qRT-PCR、酶联免疫和激光共聚焦等技术，分析相关信号从根系到地上部的运输及其对miR159/319和相应靶基因的调控，明确介导砧木调控接穗miR159/319表达的长距离信号物质及其信号传导途径。研究过表达miR159/319和相应靶基因对相关信号分子及关键基因表达的影响，揭示miR159/319的下游信号传导途径。研究可望阐明miR159/319调控嫁接西瓜低温抗性的信号传导分子机制，为调控植物抗逆性提供理论指导。

西瓜是我国乃至世界上重要的园艺作物，在我国瓜果类作物生产中占首位。然而，西瓜不耐低温，冬春低温是制约设施西瓜产业发展的重要因素。嫁接是提高园艺作物低温等逆境抗性的有效手段，但其机理尚不清楚。MicroRNA（miRNA）在植物抵御低温等逆境中起重要的调控作用。本项目在发现miR159可能参与嫁接调控西瓜低温抗性的基础上，以嫁接西瓜为材料，分析相关信号从根系到地上部的运输及其对miR159和相应靶基因的调控，明确介导砧木调控接穗miR159表达的长距离信号物质及其信号传导途径。研究过表达miR159对相关信号分子及关键基因表达的影响，揭示miR159的下游信号传导途径。. 针对生产常用南瓜或葫芦砧木影响西瓜果实品质的问题，本项目基于野生西瓜，筛选出提高西瓜低温和枯萎病抗性且不影响果实品质的优异砧木TC，为创制优异西瓜种质和选育优异砧木品种奠定了材料基础。qRT-PCR分析结果表明，正常或低温条件下，抗性砧木TC诱导了miR159的上调表达。过表达miR159前体显著提高了拟南芥植株的低温抗性。这些数据表明miR159在嫁接调控西瓜低温抗性中发挥重要作用。通过靶基因预测和qRT-PCR分析，miR159的靶基因为MYB（Cla013668、Cla006720）转录因子。进一步研究发现，褪黑素和ABA作为长距离运输信号参与了砧穗互作调控西瓜低温抗性，并解析了其信号传导分子机制。外源处理褪黑素或ABA诱导了自根嫁接植株中miR159的上调表达，而其合成抑制剂处理抵消了抗性砧木TC对miR159的诱导，表明褪黑素和ABA作为长距离运输信号参与了砧木对接穗miR159表达的调控。上述结果明确了miR159在嫁接调控西瓜低温抗性中的作用，并阐明了其信号传导分子机制，为调控植物抗逆性提供了理论指导。.