DataSheet_1_The identification and characterization of a plant height and grain length related gene hfr131 in rice.docx

Plant height and grain size are important agronomic traits affecting rice yield. Various plant hormones participate in the regulation of plant height and grain size in rice. However, how these hormones cooperate to regulate plant height and grain size is poorly understood. In this study, we identified a brassinosteroid-related gene, hfr131, from an introgression line constructed using Oryza longistaminata, that caused brassinosteroid insensitivity and reduced plant height and grain length in rice. Further study showed that hfr131 is a new allele of OsBRI1 with a single-nucleotide polymorphism (G to A) in the coding region, leading to a T988I conversion at a conserved site of the kinase domain. By combining yeast one-hybrid assays, chromatin immunoprecipitation-quantitative PCR and gene expression quantification, we demonstrated that OsARF17, an auxin response factor, could bind to the promoter region of HFR131 and positively regulated HFR131 expression, thereby regulating the plant height and grain length, and influencing brassinosteroid sensitivity. Haplotype analysis showed that the consociation of OsAFR17Hap1/HFR131Hap6 conferred an increase in grain length. Overall, this study identified hfr131 as a new allele of OsBRI1 that regulates plant height and grain length in rice, revealed that brassinosteroid and auxin might coordinate through OsARF17–HFR131 interaction, and provided a potential breeding target for improvement of rice yield.

株高与粒长是影响水稻产量的重要农艺性状。多种植物激素参与调控水稻的株高与粒型发育，但目前对于这些激素如何协同调控株高与粒型的分子机制仍不甚明晰。本研究从利用长雄蕊野生稻（Oryza longistaminata）构建的渐渗系中，鉴定得到一个与油菜素甾醇（brassinosteroid）相关的基因HFR131，该基因的存在会导致水稻产生油菜素甾醇不敏感性，并降低水稻株高与粒长。进一步研究表明，HFR131是OsBRI1的新等位基因，其编码区存在一处单核苷酸多态性（single-nucleotide polymorphism）（G突变为A），导致激酶结构域保守位点处的氨基酸发生T988I替换。本研究结合酵母单杂交（yeast one-hybrid）实验、染色质免疫共沉淀定量PCR（chromatin immunoprecipitation-quantitative PCR, ChIP-qPCR）以及基因表达定量分析，证实生长素响应因子（auxin response factor）OsARF17可结合至HFR131的启动子区域，并正向调控HFR131的表达，进而参与调控水稻株高与粒长，并影响油菜素甾醇敏感性。单倍型（haplotype）分析结果显示，OsARF17Hap1与HFR131Hap6的组合可显著提升水稻粒长。综上，本研究鉴定得到调控水稻株高与粒长的OsBRI1新等位基因HFR131，揭示了油菜素甾醇与生长素可通过OsARF17–HFR131互作实现协同调控，并为水稻产量改良提供了潜在的育种靶点。