Functional characterisation of COR27 and COR28, two novel cold-induced phytochrome- and COP1/SPA binding proteins

光和温度是决定植物生长发育的重要环境因子。一些参与光形态形成和开花诱导的转录因子是COP1/SPA E3泛素连接酶的靶标。COP1/SPA复合物的活性受到光激活的光敏色素和隐色素的下调，最近的报道表明COP1也受温度的控制。我们最近发现了两个新的光敏色素相互作用蛋白，COR27和COR28。COR27和COR28的表达在寒冷条件下得到强烈增强，转录组学数据表明，它们可能受到自主通路基因HOS1和MYB/bHLH/WDR复合物的调控，这两个基因分别参与控制开花、寒冷反应和花青素的生物合成。COR27和COR28与COP1/SPA相互作用，但似乎不是其E3泛素连接酶活性的靶标，这表明它们可能调节COP1/SPA复合物的活性，以响应光和温度。因此，COR27和COR28可能有助于光和温度信号的整合，这对于生长发育适应复杂和快速变化的环境至关重要。cor27和cor28双突变体开花较晚，过表达cor27或cor28的幼苗花青素含量增加。在本项目中，我们希望探索COR27和COR28参与光温调控的分子机制，并研究COR27和COR28如何与COP1/SPA和光敏色素一起整合光温信号来调控开花、花青素生物合成和冷响应。

Light and temperature are important environmental factors that determine plant growth and development. Several transcription factors involved in positive regulation of photomorphogenesis and induction of flowering are targets of the COP1/SPA E3 ubiquitin ligase. The activity of the COP1/SPA complex is downregulated by light-activated phytochromes and cryptochromes and recent reports show that COP1 is also controlled by temperature. We recently identified two novel phytochrome interacting proteins, COR27 and COR28. Expression of COR27 and COR28 is strongly enhanced by cold and transcriptomic data suggest that they might be regulated by autonomous pathway genes, HOS1, and the MYB/bHLH/WDR complex, which are involved in control of flowering, cold responses, and anthocyanin biosynthesis, respectively. COR27 and COR28 interact with COP1/SPA but appear not to be targets for their E3 ubiquitin ligase activity, suggesting instead that they might regulate the activity of the COP1/SPA complex in response to light and temperature. Thereby, COR27 and COR28 might contribute to light and temperature signal integration, which is important for the adaptation of growth and development to complex and rapidly changing environments. The cor27 cor28 double mutant is late flowering and seedlings overexpressing COR27 or COR28 accumulate increased levels of anthocyanin. In the proposed project we want to explore the molecular mechanisms involved in light and temperature regulation of COR27 and COR28, and investigate, how COR27 and COR28 together with COP1/SPA and phytochromes integrate light and temperature signals to regulate flowering, anthocyanin biosynthesis and cold responses.