The AtMYB2 inhibits the formation of axillary meristem in Arabidopsis by repressingRAX1gene under environmental stresses

Key message AtMYB2 protein represses the formation of axillary meristems in response to environmental stresses so that plants can undergo a shorter vegetative development stage under environmental stresses. Shoot branching is an important event determined by endogenous factors during the development of plants. The formation of axillary meristem is also significantly repressed by environmental stresses and the underlying mechanism is largely unknown. TheREGULATOR OF AXILLARY MERISTEMS(RAX) genes encode the R2R3 MYB transcription factors that have been shown to regulate the formation of axillary meristems in Arabidopsis. TheAtMYB2is also a member ofR2R3 MYBgene family whose expression is usually induced by the environmental stresses. In this study, our results showed that AtMYB2 protein plays a pivotal negative regulatory role in the formation of axillary meristem.AtMYB2is mainly expressed in the leaf axils as that ofRAX1. The environmental stresses can increase the expression of AtMYB2 protein which further inhibits the expression ofRAX1gene by binding to its promoter. Therefore, AtMYB2 protein represses the formation of axillary meristems in response to environmental stresses so that plants can undergo a shorter vegetative development stage under environmental stresses.