水稻miR156调控根系发育的分子机制

In rice (Oryza sativa), the root system is the main organ that absorbs and utilizes water and nutrients. Improved root system is the basis for high and stable yield of crops. Root-based crop improvement is an important research area. However, the regulatory mechanism of rice root development is poorly understood. In our previous work, we investigated the function of rice miRNAs by using short tandem targets mimic (STTM) technique and found that the main root and crown root were abnormally developed in those lines with significantly reduced miR156 expression. In this project, miR156 loss-of-function mutants and miR156-resistant SPL genes will be obtained through genome editing techniques. Further studies will focus on how miR156 regulates rice root development through phenotypic and physiological analysis, RNA-SEQ and ChIP-SEQ etc, including (1) how miR156 affects the morphogenesis of rice roots? (2) The relationship between miR156 and auxin pathway in regulating rice root development. (3) The molecular mechanism of miR156/SPL module regulating rice root development. The project will enrich the regulatory network of rice root development and expand the understanding of the molecular mechanism of rice root development. It also provides new targets to achieve improved crop by improving root structure.

在水稻中，根系是吸收、利用水分和营养物质的主要器官，优良的根系是作物高产及稳产的基础。基于根系的作物改良是一个重要的研究方向，然而目前对水稻根系发育的调节机制知之甚少。在前面的工作中，我们通过STTM技术降低水稻miR156的表达后，主根和冠根发育异常。在本项目中，通过基因编辑技术得到水稻miR156的功能缺失突变体及SPL抗性靶基因材料等，进而通过表型及生理学分析、RNA-SEQ及ChIP-SEQ等深入研究miR156如何调控水稻根系的发育，包括（1）miR156如何影响水稻根系的形态建成？（2）miR156是否通过生长素途径调控水稻根系的发育？（3）miR156/SPL调控水稻根系发育的分子机制。通过本项目的研究，可以丰富水稻根系发育的调控网络，扩展对水稻根系发育分子机制的认识；为水稻及其它作物中利用根系的作物改良提供新的靶点。

优良的根系是作物高产及稳产的基础，水稻的根主要有冠状根组成，但目前对水稻冠状根发育机制的了解还比较少。本项目研究表明，miR156可以通过OsSPL12直接调控下游基因OsMADS50及OsSARU21的表达，进而影响生长素合成基因OsYUC7和OsYUC9、生长素转运蛋白基因OsPIN2及生长素信号传导途径基因OsIAA23的表达从而影响生长素的合成、运输及分布等，最终影响水稻冠状根的延伸。通过本项目的研究，丰富了水稻冠状根发育的调控网络，为水稻及其它作物中利用根系的遗传改良提供新的靶点。

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