TY - JOUR T1 - The rice G protein γ subunit <em>qPE9-1</em> positively regulates grain-filling process by interacting with abscisic acid and auxin JF - bioRxiv DO - 10.1101/487850 SP - 487850 AU - Dongping Zhang AU - Minyan Zhang AU - Yong Zhou AU - Yuzhu Wang AU - Hongyingxue Chen AU - Weifeng Xu AU - Lin Zhang AU - Ting Pan AU - Bing Lv AU - Guohua Liang AU - Jiansheng Liang Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/12/05/487850.abstract N2 - The rice genome contains a single Gα (RGA1) and Gβ (RGB1) and five Gγ subunits. Recent genetic studies have shown that DEP1/qPE9-1, an atypical putative Gγ protein, is responsible for dense and erect panicles, but the biochemical and molecular mechanisms underlying control of grain size are not well understood. Here, we report that plants carrying qPE9-1 have more endosperm cells per grain than plants contain the qpe9-1 allele. The qPE9-1 line has a higher rate and longer period of starch accumulation than the qpe9-1 line. Additionally, the expression of several key genes encoding enzymes catalyzing sucrose metabolism and starch biosynthesis is higher in the qPE9-1 line than in the qpe9-1 line, especially from the mid to late grain-filling stage. Grains of the qPE9-1 line also have higher contents of two phytohormones, ABA and IAA. Exogenous application of ABA or IAA enhanced starch accumulation and the expression of genes encoding grain-filling-related enzymes in the grains of qPE9-1, whereas only IAA produced these effects in qpe9-1. Based on these results, we conclude that qPE9-1 promotes endosperm cell proliferation and positively regulates starch accumulation largely through ABA and IAA, which enhance the expression of genes encoding starch biosynthesis during the late grain-filling stage. ER -