Photoperiodic control of floral transition in Arabidopsis thaliana

点击翻译按钮获取中文摘要

To ensure reproductive success, plants have developed an elaborate genetic network that integrates endogenous and environmental factors to correctly time the onset of flowering. One of the most important factors that control this developmental switch is day length, or photoperiod. Based on grafting experiments it has been proposed that photoperiod is perceived in leaves where it leads to the induction of a flower-forming substance called florigen . The florigen is than transmitted to the shoot apex where it induces the transition to flowering. The molecular nature of the florigen has eluded characterization for the past 70 years, but recent data suggest that the mRNA of FLOWERING LOCUS T (FT) can be transmitted from the leaves to the apex where the FT protein interacts with a bZIP transcription factor FD to induce flowering. We have identified a negative regulator of floral transition, SCHLAFMÜTZE (SMZ), which represses the induction of FT in leaves. Results from misexpression of SMZ and other genes that affect either FT transcription or mRNA stability, or the FT protein level suggest the FT protein movement might be crucial for the induction of flowering. Here we propose a series of experiments to investigate the function of SMZ in regulating FT transcription, including the potential role of miR172 in this process. We will further analyze whether FT protein is able to move from the leaves to the apex. Specifically we will address the question whether FT protein movement is possible at all, as is suggested from our preliminary data, and whether this movement is necessary and sufficient to induce flowering. Finally we will analyze the role of FT/FD protein complex at the shoot apex with an emphasis on identifying direct targets.