水稻养分高效相关根构型基因的功能分析

With the increasement of our requirement for green crops, it’s emergent to breed high-efficient nutrient uptake high yield crops to lower down the amount of fertilizer application. As elite root architecture is the basis of high nutrient efficiency. It would be a nice strategy to improve root architecture for better nutrient uptake efficiency. Therefore, it will have important theoretical and practical significance to clarify the molecular mechanisms of the regulation of root architecture. We have isolated a mutant years ago, which showed less root gravitropic response with normal shoot growth. It was named Osgl1(Oryza sativa gravitropic less1) according to the phenotype.　Osgl1　showed larger root distribution area compared with wild type. It showed significant higher yield than the wild type in the field with half fertilizer application. This indicates that it’s a useful gene for agriculture practice. On the basis of gene cloning, this project will further study the molecular and biochemistry function of OsGL1. To identify its target protein by yeast two hybridization or through screening of suppressor mutant. And to clarify its function and the molecular mechanism of root gravitropic response and root architecture in order to provide useful gene and genetic material for breeding practice.

随着人们对绿色农作物需求的大量增加。当前急需培育养分高效吸收的高产作物品种，以减少化肥的施用量。而良好的根构型是养分水分高效吸收的基础。改变根构型以提高养分水分吸收效率将是一个不错的策略。因此，阐明根构型调控的分子机制将具有重要的理论和应用意义。前期本实验室曾筛选得到根向地性减弱的突变体Osgl1(Oryza sativa gravitropic less1),该突变体地上部和野生型没显著差异，在田间表现出更大的根系分布面积，在半施肥的土壤中表现为比野生型显著提高产量。表明该基因具有良好的生产应用潜力。本项目将在克隆根构型调控基因OsGL1基础上进一步阐明该基因的分子生化功能，通过酵母双杂交和抑制子突变体筛选等方法阐明该基因的下游靶基因以及他们参与根向地性及根构型的分子调控机制。以便为养分高效吸收育种提供有用的基因和遗传资源。

良好的根系构型是养分水分高效吸收的基础。阐明根构型调控的分子机制具有重要的理论和应用意义。本研究对根生长角度调控基因OsGL1进行了详细的功能分析,明确OsGL1的表达量和水稻根生长角度呈显著负相关，通过启动子接GUS转基因材料及RT-qPCR分析阐明OsGL1在根、茎、叶中都有表达，但在根中表达最高，OsGL1在细胞膜和细胞质都有定位。OsGL1在根中主要在表皮细胞表达，通过调控OsPIN2在根尖的极性定位影响根尖生长素的极性定位，进而影响根生长角度。我们也明确Osgl1突变体相比野生型有更高的养分吸收效率。另外，本研究详细分析了不定根调控基因CRD1的功能，明确CRD1是核质共同定位蛋白，影响miR156的积累进而影响不定根数目。通过图位克隆方法克隆了不定根发生调控基因LCRN1，该基因编码OsSPL3，lcrn1突变体中miR156靶位点突变造成OsSPL3转录本明显积累，进而抑制不定根发生。我们也明确LCRN1通过下游靶基因OsMADS50调控生长素信号进而影响不定根数目，同时本研究还研究水稻生长素输出转运体PIN1a-PIN1d的功能，明确它们功能冗余地参与调控不定根数目。本研究阐明OsGL1通过OsPIN2调控根生长角度；也揭示了不定根发生的重要调控路径CRD1-miR156-OsSPL3-OsMADS50。这些研究结果为阐明水稻根构型的分子机制及改良根构型提高作物养分吸收效率提供了重要的理论和材料基础。