ABSTRACT
Cyclins are important cell cycle regulators, overexpression of which may alter the plant growth. B-type cyclins (CycB) are known as mitotic cyclins. In this study, a CycB gene cloned from Nicotiana tabacum was studied. Northern analysis showed this gene has a high expression in shoot apex and flower bud. In order to further detect its function in the plant growth and development, this gene was introduced into N. tabacum genome by Agrobacterium-mediated method, driven by CaMV 35S promoter. However, the transgenic plants overproducing CycB exhibited similar growth rate to wild-type, and the flow cytometry result showed no significant difference in the cell cycle between the transgenic and wild-type plants. By contrast, overexpression of the CycB in transgenic tobacco promotes the adventitious shoot formation on leaf explant on MS medium without hormone.