OsFLZ2 interacts with OsMADS51 to fine-tune rice flowering time

Flowering time is an important agronomic trait affecting crop yield. FCS-LIKE ZINC FINGER (FLZ) proteins are plant-specific regulatory proteins that are involved in multiple biological processes. However, their roles in plant flowering time control have not been clarified. Here, we report that OsFLZ2 is a negative regulator of rice flowering time. OsFLZ2 delays flowering by repressing the expression of key floral integrator genes. Biochemical assays showed OsFLZ2 physically interacts with OsMADS51, a flowering activator under short-day (SD) conditions. Both OsFLZ2 and OsMADS51 are highly expressed in rice leaves before floral transition under natural SD conditions, and their proteins are colocalized in the nucleus. Co-expression of OsFLZ2 can destabilize OsMADS51 and weaken its transcriptional activation of the downstream target gene Early heading date 1 (Ehd1). Taken together, these results indicate that OsFLZ2 can interfere with the function of OsMADS51 to fine-tune rice flowering time.