OsGIF1 Positively Regulates the Sizes of Stems, Leaves, and Grains in Rice

Abstract

Growth-regulating factor (GRF) interacting factors (GIFs) are involved in several developmental processes in <i>Arabidopsis.</i> We previously showed that upregulation of <i>OsGIF1</i> expression improves rice grain size. However, whether <i>OsGIF1</i> is involved in other developmental processes remains unclear. Here, we report pleiotropic effects of <i>OsGIF1</i> on rice organ size regulation. Overexpression and functional knock-out via a CRISPR/Cas9 strategy revealed that <i>OsGIF1</i> not only positively regulates the sizes of rice leaf, stem, and grain but also influences rice reproduction. Expression profiles based on both qRT-PCR and <i>GUS</i> (<i>β-glucuronidase</i>) histochemical staining suggested that <i>OsGIF1</i> is differentially expressed across various rice tissues, consistent with its roles in regulating the development of multiple rice organs. Additionally, we found that OsGIF1-GFP localized preferentially in the nucleus, which supports its proposed role as a transcriptional cofactor. Further histological analysis suggested that <i>OsGIF1</i> affected rice organ size possibly by regulating cell size. Our results suggest that <i>OsGIF1</i> plays important roles in vegetative and reproductive developmental processes, with important implications for rice breeding.