适时开花对于植物生长发育至关重要。成花素是诱导植物开花的信号分子，由FT基因编码。长日照植物中，通常认为FT蛋白随光照时间表达增加，并与骨架蛋白14-3-3和转录因子FD相互作用，形成开花复合物，在长日照条件下诱导植物开花，但FT是否直接参与短日照条件下的开花过程并不清楚。以二穗短柄草作为模式，我们发现了一个受短日照条件特异诱导表达的FT (FT9)，过量表达FT9的转基因植株在短日照条件下提早开花，但长日照条件开花时间并不提前。酵母双杂交文库筛选发现，FT9与一个并非是典型FD的bZIP家族转录因子FIB相互作用；有意思的是，进一步发现FIB同样受到短日照条件诱导表达。本项目在以上研究基础上，将通过遗传学和生物化学手段，研究FT9和FIB相互作用的生物学意义，并寻找调控FT9基因的上下游作用因子。揭示FT9的分子作用机制将为深入解析植物光周期途径介导的植物开花提供新启示。

The appropriate timing of floral transition is crucial for plant reproductive success. Florigen, encoded by the FLOWERING LOCUS T (FT) gene, functions as a integrated signal to induce flowering in plants. FT protein interacts with scaffold protein 14-3-3s and the basic leucine zipper (bZIP) transcription factor FD to form a flowering initiation complex, stimulating flowering by activation of downstream floral genes. In long-day plants, it is generally thought that FT is induced by long-day conditions, while whether it can be induced and what the roles of it in short-day conditions remains elusive. Recently, we interestingly identified an FT homolog (FT9) that is specially expressed under short-days in Brachypodium distachyon. We found that over-expression of FT9 in transgenic plants is able to cause early flowering under short-day conditions, but not in long-day environments. Furthermore, we found that FT9 can interact with an untypical basic leucine zipper (bZIP) transcription factor FIB (FT interacting bZIP) rather than FD. More intriguingly, we found that FIB was also specially induced in short-days. In this project, through genetics and biochemistry approaches, we will explore the biological significance for FT9-FIB interactions and search for the upstream and downstream regulator of FT9. Our deep investigation of FT9 action mechanism will provide novel insights into the photoperiod-mediated flowering pathway in plants.