ZmSCL33调控玉米株型的分子机制

Plant architecture is a significant factor affecting planting density and grain yield in maize. Modification of plant architecture such as reducing the plant height and selecting for erect leaves has become one of the most critical researches on maize genetic breeding. Here, we cloned a gene named ZmSCL33 regulating plant height and leaf angle. In this research, we will reveal the molecular mechanism of ZmSCL33 as follows: (1) Morphological and cytological observation will be done in mutant lines of ZmSCL33. (2) BR sensitive test and BR related genes expression test will be conducted to optimize BR signing pathway. (3) By ChIP-Seq and yeast two-hybrid assay, target genes and interacting proteins will be identified to reveal the regulatory network based on ZmSCL33. (4) Find the significant haplotype in maize inbred lines. We expect to illuminate the genetic basis of ZmSCL33 that how to control the plant height and leaf angle. And the haplotype analysis will provide a valuable genetic resource for modifying plant architecture and planting density by marker assisted breeding.

玉米株型影响种植密度和田间产量，是玉米遗传育种研究的重点。株高和叶夹角是衡量玉米株型的主要形态指标。本项目发掘到转录因子ZmSCL33，同时调控玉米株高和叶夹角两个性状，其突变体具有半矮化及茎叶夹角变小的优良株型，但其调控株型的分子机制尚不清楚。为解析其作用机制，拟开展：（1）突变体形态学和细胞学观察，探究ZmSCL33影响玉米株型的细胞学基础；（2）BR敏感性测试及BR相关基因表达水平的检测，确定ZmSCL33在BR信号通路中的位置；（3）结合ChIP-Seq和酵母文库筛选等技术手段，寻找ZmSCL33所调控的靶基因及与该基因互作的蛋白，构建以ZmSCL33为核心的基因调控网络；（4）在自然变异群体中，用过单体型分析寻找ZmSCL33的优异等位基因型。期望阐明ZmSCL33同时调控玉米株高和叶夹角的遗传基础，挖掘优异等位基因型，为玉米株型改良及耐密分子育种提供理论基础和基因资源。

玉米株型影响种植密度和田间产量，是玉米遗传育种研究的重点。株高和叶夹角是衡量玉米株型的主要形态指标。本项目发掘到转录因子ZmSCL33，该基因的玉米突变体表现为株高变矮和叶夹角减小的表型。对叶枕部位观察发现，突变体中叶枕面积变小，叶枕近轴端的厚壁组织层数减少，而节间长度的变化导致植株半矮化。对叶片、叶枕和叶鞘的表皮细胞进行观察，结果表明，ZmSCL33基因功能的缺失可能导致细胞变小，进而使得玉米呈半矮化。ZmSCL33的玉米和水稻过表达株系叶夹角变大，株高并未增加，反而低于WT。进一步通过Y1H筛选到ZmSCL28的上游调控因子为ZmBEH1与ZmBZR1，而且ZmBZR1与ZmBEH1的互作。BZR1和BEH1均参与BR信号转导，通过外施BL检测该基因的突变株系对BR不敏感。ZmBZR1与ZmBEH1玉米突变体的株高、叶夹角、叶耳大小以及叶长、叶宽的表型与scl28-1突变体基本一致，ZmBZR1/ZmBEH1-ZmSCL33调控通路的发现，丰富了玉米株高和叶夹角的基因调控网络，为玉米耐密的分子育种提供理论基础和基因资源，对玉米株型改良及密植具有重要的指导意义。