Abstract:

This study investigated the effect of gibberellin on flower formation of Betula platyphylla and the possible mechanism in the process. In this experiment, different concentrations of GA₃ (50,100,200 mg·L^-1) were sprayed on the leaves of B. platyphylla at the stage of flower induction. The expression of the key genes involved in B. platyphylla flower formation in the apical meristem was studied during the period of flowering differentiation by RT-PCR. The results showed that flowering induction of B. platyphylla was in late May in Harbin and flowering transition was significantly inhibited by different concentrations of GA₃. The expression of flowering-promoted genes, including LFY, GI, ELF3 and LD, were distinct lower than the control group, while expression of the flowering suppressor gene FLC had no significant changes. Therefore, the exogenous GA₃ was of the disincentive during the flowering transition of B. platyphylla. GA₃ plays a negative role in different gene expression of the multiple flowering pathways rather than individual one.

Key words: Betula platyphylla, exogenous GA₃, flowering induction, real-time fluorescent quantitative PCR, flowering genes