BR信号转导组分BES1调控番茄果实类胡萝卜素生物合成的分子机理

Carotenoids are essential plant secondary metabolites with a range of beneficial health trait for human. Recent study has demonstrated that SlGLK2 transcription factor regulates the carotenoid biosynthesis through enhancing chloroplast development in ripe tomato (Solanum lycopersicum) fruit. AtGLK1 and AtGLK2 are direct brassinosteroid-regulated target genes of BES1, an essential regulator of BR signaling pathway. Our previous results showed that tomato fruits overexpressing Atbes1 gene (obtained from bes1-D gain-of-function mutant) exhibited “green shoulder” phenotype, which was regulated by SlGLK2 transcription factor, and enhanced carotenoids accumulation. However, the mechanism of BES1 regulation on the carotenoid biosynthesis was unknown. In this project, yeast one-hybrid, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) methods will be used based on the Atbes1 transgenic tomato fruit to investigate the molecular mechanism of BES1 regulation on SlGLK2 transcription. Furthermore, AtBES1 direct targets involved in the carotenoid biosynthesis in tomato fruit will be obtained by the ChIP-seq method. Finally, RNA interference (RNAi) method (under the fruit-specific E8 promoter) is used to elucidate the function and probable mechanism of SlBES1 on carotenoids biosynthesis. This research will enrich our understanding for the regulation network of carotenoids biosynthesis, and also will provide theoretical basis for how to enhance carotenoids levels and improve tomato fruit quality by genetic engineering.

类胡萝卜素是植物生存所必不可少的一类次生代谢物质，同时对人类健康有诸多益处。番茄果实中SlGLK2转录因子通过促进叶绿体的合成调控类胡萝卜素的积累。拟南芥中AtGLK1和AtGLK2是BR信号转导途径中起关键调节作用的BES1转录因子的靶基因。我们前期的研究发现，转Atbes1基因（从拟南芥bes1-1D功能获得型突变体中获得）的番茄果实出现了SlGLK2转录因子控制的“绿果肩”表型，且提高了类胡萝卜素的积累。本项目以Atbes1转基因番茄果实为材料，研究AtBES1转录因子调控SlGLK2基因转录的分子机制；获得番茄果实内AtBES1转录因子调控的与类胡萝卜素代谢相关的靶基因；并阐明内源SlBES1基因在番茄类胡萝卜素中的功能及可能的作用机制。该项目的实施将丰富人们对类胡萝卜素代谢网络的认识，为通过基因工程手段提高番茄果实中类胡萝卜素的含量和改善营养品质提供理论依据。