OsNF-YA8 promotes starch accumulation and influences seed traits by positively regulating starch biosynthesis in rice.

The storage substances of rice are critical factors that simultaneously affect grain yield and quality. Starch is the major component in the endosperm, directly affecting the seed yield as well as the cooking and eating quality of grains. Growing evidence suggests that some transcription factors are involved in regulating seed traits and starch biosynthesis. Here, we reveal the role of an NF-Y transcription factor gene, OsNF-YA8 , in regulation of seed traits and starch accumulation. OsNF-YA8 encodes a rice NF-YA protein containing the 166-amino acid. The RT-qPCR showed that OsNF-YA8 is expressed in roots, stems, leaves, flag leaves, and panicles, and dramatically increased in panicle during rice filling. Intracellular localization analysis showed that OsNF-YA8 is a nucleus-localized protein. In the OsNF-YA8 overexpression lines, rice grain length increased by 13.80–14.21 %, rice grain thickness decreased by 3.22–6.65 %, and the total starch content increased by 14.70–33.14 %. The overexpression of the OsNF-YA8 also decreased average starch granule size, and changed starch properties. Moreover, OsNF-YA8-overexpression up-regulated the expressions of genes involved in sucrose synthesis/transport and starch synthesis. By contrast, RNAi of OsNF-YA8 decreased the grain length, grain width, 1000 grain weight and starch content of rice seeds, and down-regulated the expressions of genes involved in sucrose synthesis/transport and starch synthesis. These results suggest that OsNF-YA8 enhances starch accumulation and confers seed traits by positively regulating starch biosynthesis in rice. The findings provide a new perspective on genetic improvement of crop agronomic traits and seed quality. [Display omitted] • OsNF-YA8 encodes a nucleus-localized protein with 166-amino acid. • The overexpression of the OsNF-YA8 confers seed improvement traits. • OsNF-YA8 promotes starch accumulation by positively regulates starch biosynthesis. • OsNF-YA8 impacts on rice grain size and physicochemical properties of starch grains. • OsNF-YA8 upregulates the expression of sucrose and starch synthesis-related genes. [ABSTRACT FROM AUTHOR]