PubMed · 2026-06-04
Scientists discovered that a protein called OsFCA helps control how long rice grains grow and when the plant flowers, with its activity precisely tuned by a molecular switch that moves it between the cell nucleus and cytoplasm.
OsFCA is phosphorylated at two specific sites (Ser-43 and Ser-45) by the kinase OsGSK3, which relocates the OsFCA complex from the nucleus to the cytoplasm and suppresses its activity
Rice plants with non-functional OsFCA (Osfca mutants) showed significantly lower sensitivity to brassinolide hormone treatment and produced shorter grains
OsFCA promotes flowering under long-day conditions by suppressing the Ghd7 gene while activating Ehd1, Hd3a, and RFT1 flowering genes, linking grain development and flowering time regulation to the same protein
