MONOCULM 3, an Ortholog of WUSCHEL in Rice, Is Required for Tiller Bud Formation

WUSCHEL (WUS) plays an essential role for the maintenance of meristem activity in dicots, but its function is still elusive in monocots. We isolated a new monoculm mutant, monoculm 3 (moc3), in which a point mutation causes the premature termination of rice O. sativa WUS (OsWUS). Morphological observation revealed that the formation of tiller buds was disrupted in moc3. MOC3 was localized in the nuclear and could interact with TOPLESS-RELATED PROTEINS (TPRs). The expression of MOC3 was induced by cytokinins and defection of MOC3 affected the expression of several two-component cytokinin response regulators, OsRRs and ORRs. Our results suggest that MOC3 is required for the formation of axillary buds and has a complex relationship with cytokinins.