Leaf angle is one of the most important agronomic traits in rice, and changes in leaf angle can alter plant architecture to affect photosynthetic efficiency and thus determine grain yield. Therefore, it is important to identify key genes controlling leaf angle and elucidate the molecular mechanisms to improve rice yield. We obtained a mutant rela (regulator of leaf angle) with reduced leaf angle in rice by EMS mutagenesis, and map-based cloning revealed that OsRELA encodes a protein of unknown function. Coincidentally, DENSE AND ERECT PANICLE 2 (DEP2) was reported in a previous study with the same gene locus. RNA-seq analysis revealed that OsRELA is involved in regulating the expression of ILI and Expansin family genes. Biochemical and genetic analyses revealed that OsRELA is able to interact with OsLIC, a negative regulator of BR signaling, through its conserved C-terminal domain, which is essential for OsRELA function in rice. The binding of OsRELA can activate the expression of downstream genes repressed by OsLIC, such as OsILI1, a positive regulator of leaf inclination in rice. Therefore, our results suggest that OsRELA can act as a transcriptional regulator and is involved in the regulation of leaf inclination by regulating the transcriptional activity of OsLIC.
葉片角是水稻最重要的農(nóng)藝性狀之一，葉片角的變化會(huì)改變植株構(gòu)型，從而影響光合效率，進(jìn)而決定籽粒產(chǎn)量。因此，識(shí)別控制葉角的關(guān)鍵基因，闡明其分子機(jī)制對(duì)水稻增產(chǎn)具有重要意義。通過EMS誘變獲得了一個(gè)葉夾角變小的突變體rela，圖位克隆表明OsRELA編碼一個(gè)功能未知的蛋白。巧合的是，在之前的研究中也報(bào)道過具有相同基因位點(diǎn)的直立密穗基因DEP2。RNA-seq分析顯示OsRELA參與調(diào)控ILI和Expansin家族基因的表達(dá)。生物化學(xué)和遺傳分析表明，OsRELA能夠通過其保守的C端結(jié)構(gòu)域與BR信號(hào)負(fù)調(diào)控因子OsLIC互作，這對(duì)OsRELA在水稻中的功能至關(guān)重要。OsRELA的結(jié)合可以激活被OsLIC抑制的下游基因的表達(dá)，如水稻葉片傾角正調(diào)控因子OsILI1。因此，我們的結(jié)果表明，OsRELA可以作為一個(gè)轉(zhuǎn)錄調(diào)控因子，通過調(diào)控OsLIC的轉(zhuǎn)錄活性參與葉片傾角的調(diào)控。