水稻LAZY-LIKE基因的向重性调控研究

Gravitropism plays a key role in rice architecture, its research will help to get the ideal plant architecture to increase production. While, there is rare mutation materials to understand gravitropism regulation pathways currently. Our group found a novel spread-out growth rice mutant, a multiple copies T-DNA insertion mutant. Candidate gene LAL was isolated from the low copies T-DNA insertion lal produced by backcross. Cytological experiments showed its spread-out growth was caused by asymmetric cell growth, and LAL may be regulated by LAZY1, PROG1, or TAC1. This study will first identify the LAL gene which caused the spread-out plant architecture by co-segregation analysis. Then study its biological function through bio-information analysis, expression pattern analysis, and complementary experiment. Further, the polar auxin transport and protein localization were performed to analysis its function mechanism. Finally LAZY1 CRISPER or PROG1 and TAC1 over-expression transgenic plants and lal were detected to identify the regulation relation between the essential gravitropism regulation genes and LAL, and then proved by genetic experiments. This study will help to reveal the gravity response regulation network in cereal crops and the mysteries of spread-out growth rice turned into upright growth, and will provide resources for genetic improvement of plant architecture.

水稻地上部分向重性是决定水稻株型的一个主要因素，株型将影响水稻的产量。由于缺少理想的突变材料，目前对该调控途径知之甚少。前期本课题组获得了一地上部分重力响应严重缺失T-DNA插入导致的散生突变体lazy-like（lal），细胞学实验显示其散生是由细胞的不对称生长引起，定量PCR结果暗示LAL可能位于向重性负调控基因LAZY1或正调控基因PROG1和TAC1的下游。本项目将通过生物信息学分析、时空表达、共分离检测、互补实验研究LAL的生物学功能；从蛋白定位和生长素极性运输等分析其作用方式；最后对LAZY1 CRISPER、PROG1或TAC1的超表达植株及lal进行表达检测以探索LAL与上述基因是否存在调控关系，并通过遗传学实验验证。通过此研究，将有助于揭示禾本科作物地上部分向重性反应中LAL的调控机制以及水稻由散生变为直立生长的奥秘，为水稻理想株型的遗传改良提供基因资源。

地上部分向重性是决定水稻株型、影响产量的一个主要因素。近年来研究发现了LAZY1等向重性决定基因，但由于缺少理想的突变材料，对其调控途经和网络所知甚少。在本项目中鉴定得到一个新的lazy1 T-DNA插入突变体，通过共表达、转录组、酵母单杂筛库研究了LAZY1的功能、调控网络及其应用。重要结果及关键数据如下：1.鉴定获得新的ZH11背景的LAZY1 T-DNA插入突变体lazy1-4；2.LAZY1在胚芽中高表达，在基因组范围内筛选获得88个胚芽高表达基因OsPlus，其启动子含有胚芽发育相关的Pyrimidine box，DOF等元件；共表达网络分析表明OsPlus参与脂肪酸，激素等过程。3.对lazy1-4幼苗的研究发现其能够抑制脂类的代谢和运输。4.根据DEGs得到一下游生长素响应基因OsSAUR10，通过对其表达、亚细胞定位和功能研究发现OsSAUR10可通过响应LAZY1途径的生长素变化从而影响幼苗生长；5.以LAZY1启动子进行筛选4-DAG幼苗所构建的酵母单杂文库，接着以pABAi单杂和Dual-LUC验证得到LAZY1的上游调控因子OsDOF-x，其在幼苗、剑叶、花药等组织高表达，OsDOF-x超表达可形成矮化的紧密直立株型。6.基于RiceVarMap网站的529份水稻材料的SNP和InDel数据，得到LAZY1在2585-2607 bp处存在可用于分蘖角筛选的分子标记，其Tajima’s D为3.32，说明LAZY1在进化和驯化过程中发生了平衡选择。本项目获得了LAZY1的上游调控因子和下游响应基因，完善了向重性响应的调控网络；发现LAZY1抑制幼苗中脂类的代谢和分布；探索了LAZY1在进化和驯化过程中发生的选择及其在株型育种中的应用。