开花时间早晚直接决定作物品种的广适性。作为最重要的开花路径整合因子，成花素由FT基因编码，在不同植物中相当保守。尽管目前报道了大量FT基因调控因子，但其均在转录水平调控FT，FT 是否受转录后水平少有报道。经前期青年基金支持，我们发现了模式植物短柄草中miR5200可以通过剪切FT mRNA直接参与光周期介导的植物开花过程。然而，miR5200受光周期路径哪些蛋白的直接调控、miR5200是否受其他开花路径的影响还不清楚。本项目将通过遗传学、分子生物学等方法，开展三方面研究：（1）寻找光周期路径中调节miR5200表达的直接上游因子；（2）阐明miR5200上游调控因子的分子作用机制；（3）明确miR5200表达是否受环境温度、植物激素开花路径的影响。本研究不仅将为解析植物在转录后水平调控FT基因表达的分子机制提供直接基础，而且将为小麦等温带禾谷类作物广适性育种提供理论依据。

The time of flowering is critical for the adaptation of plants to a given environment. As the most important integrator in endogenous and environmental flowering pathways, the florigen protein FT has been the focus of attention for many plant scientists. So far, the findings about FT regulation have only been centered on players transcriptionally controlling FT, yet other layers of FT modulation remain elusive. Supported by previous NSFC, we identified a miRNA (miR5200) that modulated FT othologous mRNAs and played an important role in photoperiod-mediated flowering time control in Brachypodium. Nevertheless, we still didn’t know which components in day-length pathway could directly influence miR5200 expression and whether miR5200 is involved in plant hormone and ambient temperature flowering pathways. In this project, through genetics and molecular biological approaches, we will perform three aspects of research on miR5200, including: (1) Identify proteins acting on miR5200 upstream in photoperiod flowering pathway; (2) Investigate the function mechanism of miR5200 regulators; (3) Clarify the flowering pathways that miR5200 involves in. Results from this project will not only provide novel molecular insights into FT regulation at posttranscriptional level, but may also set a foundation for developing technologies to improve heading-date traits in temperate cereals.