Key Laboratory of Herbage & Endemic Crop Biology of Ministry of Education, Inner Mongolia Key Laboratory of Herbage & Endemic Crop Biotechnology, School of Life Sciences, Inner Mongolia University, Hohhot 010000, China; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China.
Mol Plant. 2021 Oct 4;14(10):1683-1698. doi: 10.1016/j.molp.2021.06.023. Epub 2021 Jun 27.
Grain size is one of the most important factors that control rice yield, as it is associated with grain weight (GW). To date, dozens of rice genes that regulate grain size have been isolated; however, the regulatory mechanism underlying GW control is not fully understood. Here, the quantitative trait locus qGL5 for grain length (GL) and GW was identified in recombinant inbred lines of 9311 and Nipponbare (NPB) and fine mapped to a candidate gene, OsAUX3. Sequence variations between 9311 and NPB in the OsAUX3 promoter and loss of function of OsAUX3 led to higher GL and GW. RNA sequencing, gene expression quantification, dual-luciferase reporter assays, chromatin immunoprecipitation-quantitative PCR, and yeast one-hybrid assays demonstrated that OsARF6 is an upstream transcription factor regulating the expression of OsAUX3. OsARF6 binds directly to the auxin response elements of the OsAUX3 promoter, covering a single-nucleotide polymorphism site between 9311 and NPB/Dongjin/Hwayoung, and thereby controls GL by altering longitudinal expansion and auxin distribution/content in glume cells. Furthermore, we showed that miR167a positively regulate GL and GW by directing OsARF6 mRNA silencing. Taken together, our study reveals that a novel miR167a-OsARF6-OsAUX3 module regulates GL and GW in rice, providing a potential target for the improvement of rice yield.
粒型是控制水稻产量的最重要因素之一，因为它与粒重（GW）有关。迄今为止，已经分离出数十个调节粒型的水稻基因，但 GW 控制的调控机制尚未完全了解。在这里，在 9311 和 Nipponbare（NPB）的重组自交系中鉴定了控制粒长（GL）和 GW 的数量性状位点 qGL5，并将其精细定位到候选基因 OsAUX3。9311 和 NPB 之间在 OsAUX3 启动子中的序列变异和 OsAUX3 的功能丧失导致 GL 和 GW 升高。RNA 测序、基因表达定量、双荧光素酶报告基因测定、染色质免疫沉淀定量 PCR 和酵母单杂交测定表明，OsARF6 是调节 OsAUX3 表达的上游转录因子。OsARF6 直接结合到 OsAUX3 启动子的生长素反应元件上，覆盖 9311 和 NPB/Dongjin/Hwayoung 之间的单个核苷酸多态性位点，从而通过改变颖壳细胞的纵向扩张和生长素分布/含量来控制 GL。此外，我们表明 miR167a 通过指导 OsARF6 mRNA 沉默正向调节 GL 和 GW。总之，我们的研究表明，一个新的 miR167a-OsARF6-OsAUX3 模块调节水稻的 GL 和 GW，为提高水稻产量提供了一个潜在的目标。
