组蛋白修饰相关基因CsPHD1调控茶树越冬芽休眠解除的功能及分子机制

芽休眠是茶树抵御冬季冻害的防御机制，春季越冬芽休眠的解除是影响名优茶生产的关键因素之一。PHD转录因子以组蛋白修饰的方式调控植物生命周期。申请人在‘龙井43’不同休眠状态的芽中发现了差异表达基因CsPHD1具有顶芽和腋芽高表达的组织特异性；不同物候期茶树品种CsPHD1的表达量均在芽休眠时最低，休眠解除时最高，且与芽休眠解除的早晚呈正相关；CsPHD1响应赤霉素（GA）和光信号。结果暗示CsPHD1参与越冬芽休眠解除。本项目拟运用免疫荧光的方法确认CsPHD1是否调控组蛋白修饰，运用ChIP-Seq挖掘被修饰的基因；利用过表达杨树植株明确CsPHD1的生理功能；利用过表达茶树愈伤组织进行ChIP-Seq并确定下游靶基因；通过酵母单杂交筛选、凝胶阻滞和双荧光素酶报告系统，明确CsPHD1的上游基因。本项目将阐明CsPHD1调控越冬芽休眠解除的分子机理，为早生优质茶树品种选育提供新的理论依据。

Bud dormancy is the defense mechanism of tea plants against winter freezing injury, and the dormancy release of overwintering buds is one of the key factors affecting the production of elite tea. PHD transcription factors regulate plant life cycle by histone modification. The applicant has found that a differentially expression gene CsPHD1 in buds of different dormancy states of 'Longjing 43' had tissue specificity of high expression in terminal buds and axillary buds. And in different tea cultivars, the expression of CsPHD1 was the lowest in bud dormancy and the highest in dormancy release, which was positively correlated with the time of bud dormancy release. Meanwhile, CsPHD1 responded to Gibberellin (GA) and light signal. These results suggested that CsPHD1 was involved in the dormancy release of overwintering buds. In this project, immunofluorescence will be used to confirm whether CsPHD1 regulates histone modifications and ChIP-Seq will be performed to dig out the histone modified genes. The physiological function of CsPHD1 will be characterized by overexpression transgenic poplar plants. ChIP-Seq will be performed by overexpression transgenic tea callus and the downstream target genes will be found. The upstream genes of CsPHD1 will be obtained by yeast one hybrid screening library and they will be verified by EMSA and DLR. This project will clarify the molecular mechanism of CsPHD1 regulating the dormancy release of overwintering buds. Meanwhile, it will provide a new theoretical basis for the breeding of early-sprouting and elite tea varieties.