番茄DELLA-GA540-HDA1复合体调控赤霉素信号途径的分子机制研究

赤霉素是植物生长发育必需的植物激素，DELLA蛋白则是赤霉素信号通路中关键的转录抑制子，但DELLA发挥转录抑制功能的分子机理尚不清楚。项目申请人利用酵母双杂交系统在番茄中鉴定到一个DELLA互作蛋白GA540，其编码转录抑制复合体组装蛋白。CRISPR/Cas9创制的突变体证实GA540负向调控赤霉素信号途径。进一步研究发现GA540与组蛋白去乙酰化酶HDA1互作，暗示DELLA与GA540，HDA1形成功能复合物调控赤霉素信号途径。基于此，本项目拟以番茄为材料，利用遗传学、生物化学和生物信息学等手段，研究DELLA-GA540-HDA1模块互作机制，解析DELLA与GA540共有靶基因，揭示DELLA和GA540对靶基因组蛋白乙酰化修饰和基因转录影响。研究成果将揭示DELLA发挥转录抑制的作用机理，揭示染色质修饰因子在调控GA信号通路中的作用，为GA在番茄遗传改良中的应用提供依据。

Gibberellins (GAs) are the essential phytohormones that control many aspects of plant growth and development. DELLA acts as a transcriptional repressor of the gibberellin signaling. However, it remains to be answered that how DELLA exerts its repression function on transcrisption. Here, using yeast two-hybrid system, we identified a DELLA-interacting protein GA540, which was predicted to be a member of the transcriptional inhibitory complex. KO-ga540 mutants created by CRISPR/Cas9 gene editing system confirmed that GA540 negatively regulates the gibberellin signaling pathway. Additionally, GA540 interacts with the histone deacetylase HDA1, suggesting that DELLA represses transcription by forming a functional complex with GA540 and HDA1. Based on the hypothesis, by using multidisciplinary research strategies such as genetics, biochemistry and bioinformatics, the project intends to study the working mechanism of the DELLA-GA540-HDA1 module, analyze the common target genes of DELLA and GA540, illustrate the effects of DELLA and GA540 on the level of histone acetylation and gene transcription in tomato. The results will shed new light on our understanding of how DELLA exhibits its repressive biological functions, uncover the role of chromatin modifiers in modulating gibberellin signaling and provide scientific basis for the application of gibberellin in molecular design breeding of tomato.