植物SUMO E3连接酶SIZ1在干旱等非生物胁迫信号转导中具有重要作用。前期研究表明，以ZmSIZ1及其表达的环状RNA（CircSIZ1）为中心节点的调控模块与玉米干旱胁迫下植株存活率紧密关联，但其相关功能和作用机制尚不清楚。本研究拟克隆ZmSIZ1和CircSIZ1，构建过表达、RNAi和CRISPR/Cas9敲除载体，并在玉米中进行遗传转化。通过对各转基因植株耐旱性鉴定和相关生理生化指标分析，明晰ZmSIZ1和CircSIZ1在干旱胁迫应答中的生物学功能。同时，针对CircSIZ1进行RNA Pull-down等实验，发掘CircSIZ1 RNA结合蛋白。在检验CircSIZ1翻译能力基础上，利用CoIP和ChIP-seq等技术，挖掘CircSIZ1互作蛋白和靶基因，以期从RNA和蛋白不同层面揭示circRNA作用机制，解析以ZmSIZ1为中心的玉米根系应答干旱胁迫的分子调控网络。

Drought is one of the major disasters in maize production. To help survive in continuous environmental challenges, plants have evolved numerous mechanisms to detect stress and mitigate the damage inflicted. The plant SUMO E3 ligase SIZ1 plays an important role in abiotic stress signal transduction and abiotic stress resistance. We identified a gene regulatory module that significantly associated with maize plant survival rate under drought stress and centered by ZmSIZ1 and its CircRNA (CircSIZ1). The biological functions of maize ZmSIZ1 in drought stress response is rarely reported, especially the function of its CircRNA, generated from the exons of ZmSIZ1 and significantly increasing in expression under drought stress, is still largely unknown. In this study, the full cDNA length of ZmSIZ1 and CircSIZ1, will be cloned and vectors for functional research, including the overexpression, RNA interference and CRISPR/Cas9 knockout vectors, will be constructed. Then the genetic transformation will be performed in maize. Different types of transgenic plants will be obtained and their phenotypic variations under drought stress will be observed. In addition, the relevant physiological and biochemical experiments will be carried out to find out the differences among different transgenic plants and wild type. On the other hand, sequences specific probes for CircSIZ1 will be designed to pull down proteins that interact with CircSIZ1 by using RNA Pull down. To obtain direct evidence for translation of CircSIZ1, sucrose density gradient centrifugation will be carried out to isolate polysome-bound RNAs for CircSIZ1 quantitative study. On the basis of confirmed translation potential of CircSIZ1, the interaction proteins for CircSIZ1, as well as its downstream regulated genes could be identified by CoIP and ChIP-seq assays. Thus, the circRNA mediated maize drought response mechanism could be revealed both from transcript and translation levels. The results from this study will unveil the ZmSIZ1 centered molecular regulatory network for maize drought tolerance and provide better strategy to maize abiotic stress resistant breeding.