细茎柱花草生物钟元件SgGIs参与低温响应的作用机理解析

柱花草属植物是重要的南方特色牧草，普遍不耐低温和霜冻。细茎柱花草是圭亚那柱花草的变种，具有良好的耐寒特性。我们前期研究发现细茎柱花草生物钟功能基因SgGIs的过量表达和它的耐寒特性密切相关。但目前国内外研究对GI参与植物低温响应的具体作用机理并不清楚。因此本项目拟通过定量PCR分析SgGIs在不同低温环境、不同细茎柱花草组织器官中的表达模式，并比较不同抗寒性的柱花草品系中SgGIs的表达差异；构建SgGIs过表达载体并转化拟南芥gi-3突变体，验证SgGIs的生物学功能；对细茎柱花草进行SgGIs过表达和基因沉默的转化，探索SgGIs的表达与抗寒性之间的关系；最后通过对转化植株的全转录组测序和分析，筛选SgGIs参与调控的低温响应通路和基因。本项目不仅有助于阐明GI参与植物低温响应的具体作用机理，还能为柱花草的抗寒育种提供新的候选基因和研究思路。

Stylosanthes are important forage in Southern China. Most species are sensitive to low temperature. Fine-stem stylo is a variant of S. guainensis which shows superior cold tolerance. Our previous research demonstrated that the over-expression of SgGIs, the core components of circadian clock model, was highly related to the cold tolerance in fine-stem stylo. However, it is still unclear how GI functions in cold responses of plants. In this project, the expression patterns of the two SgGIs in different tissues of fine-stem Stylo under different cold treatment will be determined through Realtime PCR, and SgGIs expression be compared between Stylos of different cold-tolerance; Biological function of SgGIs will be verified through over-expression of SgGIs in Arabidopsis thaliana gi-3 mutant; The correlation between SgGIs expression and cold tolerance in fine-stem stylo will be explored through over-expression and gene silencing of SgGIs; The transformant transcriptomes will be sequenced to screen for cold-responsive genes and pathways regulated by SgGIs. This project will help explore the mechanism of GI regulation on cold tolerance in plants, and also provide new candidate genes and thoughts for cold-tolerant breeding in Stylosanthes.