TY - JOUR AU - Li, Yangyang AU - He, Peilong AU - Wang, Xiaowen AU - Chen, Hongyan AU - Ni, Jile AU - Tian, Weijiang AU - Zhang, Xiaobo AU - Cui, Zhibo AU - He, Guanghua AU - Sang, Xianchun PY - 2023 TI - FGW1, a protein containing DUF630 and DUF632 domains, regulates grain size and filling in Oryza sativa L. JO - The Crop Journal SN - 2095-5421 SP - 1390 EP - 1400 VL - 11 IS - 5 AB - Grain filling influences grain size and quality in cereal crops. The molecular mechanisms that regulate grain endosperm development remain elusive. In this study, we characterized a filling-defective and grain width mutant, fgw1, whose mutation increased rice seed width mainly via cell division and expansion in grains. Sucrose contents were higher but starch contents lower in the fgw1 mutant during the grain-filling stage, resulting in inferior endosperm of opaque, white appearance with loosely packed starch granules. Map-based cloning revealed that FGW1 encoded a protein containing DUF630/DUF632 domains, localized in the plasma membrane with preferential expression in the panicle. RNA interference in FGW1 resulted in increased grain width and weight, whereas overexpression of FGW1 led to slightly narrower kernels and better grain filling. In a yeast two-hybrid assay, FGW1 interacted directly with the 14–3–3 protein GF14f, bimolecular fluorescence complementation verified that the site of interaction was the membrane, and the mutated FGW1 protein failed to interact with GF14f. The expression of GF14f was down-regulated in fgw1, and the activities of AGPase, StSase, and SuSase in the endosperm of fgw1 increased similarly to those of a reported GF14f-RNAi. Transcriptome analysis indicated that FGW1 also regulates cellular processes and carbohydrate metabolism. Thus, FGW1 regulated grain formation via the GF14f pathway. UR - https://doi.org/10.1016/j.cj.2023.03.015 DO - 10.1016/j.cj.2023.03.015