荔枝miRNA的鉴定及其在饥饿胁迫诱导落果过程中的作用机制

项目名称： 荔枝miRNA的鉴定及其在饥饿胁迫诱导落果过程中的作用机制

项目编号： No.31471859

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 农业科学

项目作者： 李建国

作者单位： 华南农业大学

项目金额： 85万元

中文摘要： 在模式植物和栽培作物上均未见miRNA与器官脱落关系的文献报导。器官脱落是一个与胁迫和衰老相关的生物学现象，基于miRNA参与植物胁迫和衰老过程调控以及碳素营养和内源激素是控制果实脱落的两大关键原因的认识，推测miRNA可能通过调控IAA、乙烯代谢和信号转导参与果实的脱落。本项目以荔枝为试材，通过碳水化合物饥饿胁迫诱导果实脱落为切入点，采用小RNA和降解组测序技术和生物信息分析等方法，构建荔枝物种和响应饥饿胁迫诱导的 miRNA及其靶基因两个数据库；筛选参与调控IAA、乙烯代谢和信号转导相关联的 miRNA及靶基因，并分析它们在落果过程中动态表达变化及其与落果率、果实中 IAA 和乙烯、近轴端和远轴端中离区 IAA和ACC含量等指标关系，进而确定与落果相关的候选miRNA及靶基因；设计外喷IAA和乙烯利的试验对候选miRNA进行验证，最终找出与果实脱落相关的miRNA并揭示其作用机制。

中文关键词： 荔枝；落果；miRNA；饥饿胁迫；内源激素

英文摘要： The relationship between microRNA and organ shedding has not so far been documented both in model plants and cultivated crops. The organ shedding is associated with plant abiotic stress and senescence that is regarded as being involved in miRNA-mediated regulation, and carbohydrates and endogenous hormones are the two key factors controlling fruit abscission. So we speculate that miRNA might be as key regulators in the process of organ abscission by affecting IAA, ethylene metabolism and signal transduction. In this project, the litchi which is originated and largest cultivated in south China is selected and the experiment of fruit abscission induced by carbohydrate starvation-stressed through defoliation plus girdling treatment will be conducted as entry point. Twenty-one small RNA libraries and one degradome libraries will be constructed，and high-throughput sequencing and degradome analysis are employed to identify known and novel miRNAs and their targets in the litchi; different expressed miRNA profiling among samples (0hr,6hr,12hr,1d and 2d) with and without defoliation plus girdling treatment will be analyzed by informatics, miRNAs and their targets response to starvation will be screened and miRNA related to fruitlet abscission will also be discovered , which will be validated by qRT-PCR and analyzed in relation to the dynamic changes of fruit drop and endogenous hormones (IAA and ethylene in fruit, ACC in abscission zone, IAA in proximal and distal abscission zones). Finally, the selected key miRNA and its targets related to fruit abscission will be tested using another experimental system like spraying IAA and ethylene. These results will provide valuable information to understand the mechanism of miRNA-mediated signaling involved in fruit abscission induced by starvation stress in litchi. Therefore, this proposal aims not only at fruit abscission which is a key scientific issue affecting yield in fruit production, but also explores in the relationship between miRNA and organ shedding which is the forefront of academic disciplines.

英文关键词： Litchi;Fruit abscission;miRNA;Starvation-stress;Endogenous Hormone