Remorins are a diverse family of plant-specific proteins with variable N-terminal sequence and conserved C-terminal sequence which is linked with plasma membrane.19 remorin members in rice display diverse function in various growth and development processes.In our studies,a rice T-DNA insertion mutant gsd1-D (grain setting defect 1-Dominant) is characterized.GSD1 is a remorin gene (remorin 6.6) and expressed specifically in phloem companion cells and is localized in the plasmodesmata (PD) and plasma membrane.The study demonstrated that GSD1 plays a role in regulating photoassimilate translocation through the symplastic pathway to impact grain setting in rice.Characterization of another rice remorin gene,OsREM4.1,indicates that OsREM4.1 expression is up-regulated by ABA through the transcriptional activator OsbZIP23.OsREM4.1 directly interacts with OsSERK1 to repress BR signaling output by inhibiting the formation and/or activation of the OsBRI1-OsSERK1 receptor complex.OsREM4.1 can be phosphorylated by active OsBRI1 and the phosphorylated OsREM4.1 is released from OsSERK1,thus allowing the formation of OsBRI1-OsSERK1 complex and subsequent activation of the BR signaling pathway.This finding reveals the OsREM4.1 function in coordinating the antagonistic interaction between ABA and BR signaling in rice.