Wu, MinggangDormancy is an adaptive mechanism that enables plants to survive unfavorable environmental conditions and resume growth when the conditions become favorable again. Bud formation is the morphological event associated with bud dormancy. The research presented in this thesis focuses on the role of PtFD1, a bZIP transcription factor, in apical bud development in poplar. This research included the construction of binary Agrobacterium vectors for the overexpressing of PtFD1 and for down regulation or silencing of PtFD1 expression using RNAi technology. These vectors were used to create transgenic poplars (Populus alba×Populus tremula) with altered expression of PtFD1. The overexpression of PtFD1 prevented apical bud development while apical bud development appeared normal in PtFD1 RNAi expressing plants. Flowering was also induced in long days in poplars overexpressing PtFD1. Anatomical studies indicate that overexpression of PtFD1 impinges on bud scale development during short day induced bud formation.en-USThesisAgriculture, Horticulture