AUTHOR=Hu Li , Chen Weilan , Yang Wen , Li Xiaoling , Zhang Cheng , Zhang Xiaoyu , Zheng Ling , Zhu Xiaobo , Yin Junjie , Qin Peng , Wang Yuping , Ma Bingtian , Li Shigui , Yuan Hua , Tu Bin 

TITLE=OsSPL9 Regulates Grain Number and Grain Yield in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.682018

DOI=10.3389/fpls.2021.682018

ISSN=1664-462X

ABSTRACT=<p>Rice grain yield consists of several key components, including tiller number, grain number per panicle (GNP), and grain weight. Among them, GNP is mainly determined by panicle branches and spikelet formation. In this study, we identified a gene affecting GNP and grain yield, <italic>OsSPL9</italic>, which encodes SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family proteins. The mutation of <italic>OsSPL9</italic> significantly reduced secondary branches and GNP. <italic>OsSPL9</italic> was highly expressed in the early developing young panicles, consistent with its function of regulating panicle development. By combining expression analysis and dual-luciferase assays, we further confirmed that OsSPL9 directly activates the expression of <italic>RCN1</italic> (rice TERMINAL FLOWER 1/CENTRORADIALIS homolog) in the early developing young panicle to regulate the panicle branches and GNP. Haplotype analysis showed that Hap3 and Hap4 of <italic>OsSPL9</italic> might be favorable haplotypes contributing to high GNP in rice. These results provide new insights on high grain number breeding in rice.</p>