水稻中ELAV/Hu类RNA结合蛋白的功能特征和作用机理研究

Post-transcriptional regulation of gene expression is very important for the growth, development and stress resistance in eukaryotes. RNA binding protein interacting with RNA to form a ribonucleoprotein complex, directly or indirectly, is involved in mRNA precursor processing, such as RNA splicing, editing, transport, RNA stability and translation. RNA binding protein plays a key role in post-transcriptional regulation. We screen an abnormal floral organ phenotype mutant in rice, the candidate gene which encodes RNA binding protein containing the RNA recognition sequence, belongs to the ELAV/Hu-like gene family. The mutant displays undegraded bract, smaller palea, and the palea and lemma unlocked after the seed filling. In this research, we will focus on uncovering the function of the ELAV/Hu-like RNA binding protein in the rice growth, development and the expression regulation of floral organ identity genes by forward and reverse genetics approaches; investigating the evolution of ELAV/Hu-like RNA binding protein in plants and animals; identifying the target mRNA sequence by the RNA binding protein immunoprecipitation (RIP) and RIP-Seq assays. This research will not only help us further improve the regulation of floral organ development network, but also provide a chance to understand the post-transcriptional regulation mechanisms of gene expression in plant growth and development.

在真核生物中，基因表达的转录后调控对生长、发育和抗逆至关重要。RNA结合蛋白与RNA相互作用形成核糖核蛋白复合体，直接或间接地参与转录后mRNA前体的剪切、编辑、运输、稳定性保持和降解、翻译等过程，在其中发挥重要作用。我们得到一个水稻花器官异常的突变体株系，该性状候选基因编码一个包含RNA识别序列蛋白，属于ELAV/Hu类基因家族。该突变体表现出苞叶不退化、内稃变小、种子灌浆膨大后内外稃不能闭合的表型。本项目申请将以突变体为材料通过正向和反向遗传学的方法研究ELAV/Hu类RNA结合蛋白在水稻生长发育过程中的功能及其在调控花器官特征基因表达中的作用；探讨ELAV/Hu类RNA结合蛋白在动、植物进化过程中功能演化；并进一步利用RNA结合蛋白免疫沉淀和高通量测序技术鉴定该蛋白的靶mRNA序列。该研究将进一步完善花器官的发育调控网络，为植物生长发育的转录后基因表达调控研究奠定基础。

RNA结合蛋白能够与RNA相互作用形成核糖核蛋白复合体，直接或者间接地参与转录后mRNA前体的剪切、编辑、运输、翻译和降解等过程。本项目通过我们发现的一个水稻花器官异常的突变体的研究，克隆了该性状的候选编码基因EHL1。 该基因编码的蛋白质包含了RNA识别序列，属于ELAV/Hu类家族。详细的表型观察分析表明该基因的T-DNA插入突变和基因编辑突变能够引起水稻苞叶不退化、内稃变小、种子膨大后内外稃片不能闭合，说明该ELAV/Hu类基因编码蛋白在水稻生长发育尤其是花发育过程中发挥了重要功能。进一步我们通过亚细胞定位和EMSA实验证明该蛋白定位于细胞核并能够直接结合水稻花器官决定MADS-Box基因OsMADS15和OsMADS34转录本的3'-UTR区域，进而调控水稻花器官的发育。该研究将有助于进一步完善水稻花器官发育调控网络。