玉米ZmSET1调控株高的分子机理

Plant height is one of most important agronomic traits associated with biomass, yield, and lodging resistance. Plants with short stature had a major impact on world agriculture. This notion is best exemplified by the success of the green revolution, which was made possible by the advent of dwarf varieties of rice and wheat. Agronomic interest in short plants derives largely from their ability to resist lodging caused by wind, rain, or higher densities, which allows them to effectively convert increased fertilizer input into higher yields . Elongation of plant parts is a complex phenomenon mediated by many plant hormones, including gibberellins(GAs), brassinosteroids, auxins, and strigolactone. Moreover, The previous results show that histone modification is one of factors of hight control in Zea Mays. However, The maize dwarfs mediated by histone modifications are poorly understood. Our evidence show that ZmSET1 encoding a SET domain proteins, a putative histone methyltransferase is involved in maize height. Loss-of-function of ZmSET1, inserted by Mu transposon, has multiple phenotypes including dwarfs, slow growth and late flowering. Take together, our project is to understand the molecular mechanisms of zmset1 mutant in maize architecture development.

株高是与作物生物量、产量以及抗倒伏性等性状紧密相关的重要农艺性状，其调控分子机理研究具有重要的理论与应用研究意义。作物的矮杆性状是一个复杂性状，受多基因控制，前人通过多个玉米、水稻株高突变体的鉴定、分离，阐述了多个赤霉素、油菜素内脂、生长素和独角金内酯等途径调控株高的基因及其机制。多个研究也表明，组蛋白甲基化修饰参与了禾本科作物包括玉米株高调控，然而其调控机制仍不明确。zmset1是一个Mu转座子插入一个具有SET结构域的蛋白ZmSET1，具有植株矮小、发育迟缓的表型。在前期明确的分子特征与生理分析鉴定的基础之上，本申请拟通过玉米组蛋白甲基化转移酶突变体zmset1，着重解析组蛋白修饰在玉米生长发育中的作用，阐述组蛋白甲基化调控作物株型的分子机理。本研究将阐明组蛋白甲基化修饰基因及其途径参与和调控玉米等高等植物株高等株型建成机制。

玉米的株高，叶夹角，是玉米重要的农艺术性状，决定着玉米的产量。本研究发现玉米ZmSET1促进玉米株高增长和减小叶夹角。ZmSET1互补拟南芥atx1花发育和早开花的表型，表明ZmSET1是ATX1的同源蛋白，具有H3第四位甲基转移酶的功能。我们通过RNAi的方式获得Zmset1突变体，发现突变体高度降低，且叶夹角增大。组织切片显示，Zmset1突变体的叶原基部分没有任何的变化，而叶鞘和叶耳的薄壁组织变薄，且叶耳中的维管束变窄，叶耳的表面不平滑，且大维管束的距离增加，表明ZmSET1可能参与了生长激素的调节，基因表达水平显示：与生长素合成相关的基因，如YUC的表达水平明显上升起。为了进一步研究ZmSET1的功能，我们通过酵母双杂交系统，筛选其相互作用蛋白。结果显示：ZmSET1能与具有DELLA结构域的蛋白ZmGA1互作，表明ZmSET1可能参与了玉米的赤霉素信号来调控玉米的生长发育，其中zmga1的突变体，已经获得，相关的表型工作正在展开。