植物与根际微生物进行物质交换和信号通讯对于植物生长和微生物群落的动态平衡有非常重要的意义。前期研究表明，根际促生菌荧光假单胞菌分泌的一种广谱抗菌活性的抗生素2,4-二乙酰基间苯三酚（2,4-DAPG）作为信号分子影响和调控一些植物共生菌的生理活动。然而根际促生菌感受与应答2,4-DAPG及中间代谢产物MAPG的分子机制及生物学功能还缺乏系统深入的研究。本项目将以根际促生菌荧光假单胞菌Pf-5为例，结合微生物学、生化与分子生物学、结构生物学的原理和方法，通过微生物生理指标来筛选鉴定2,4-DAPG及MAPG的信号分子作用，研究关键转录调控因子PhlH和PhlF对信号分子的响应机理和对DNA的识别机制，建立PhlH和PhlF的精确调控模型，寻找新的PhlH和PhlF调控的下游基因，加深对根际促生菌次生代谢产物在种内信号通讯中发挥作用分子机制的理解，为环境友好型生物防治的研究和开发提供理论依据。

The mass-exchange and signal transduction between the root and microorganisms play a vital role in maintaining plant growth and dynamic balance of microbial community. Previous studies have shown that 2,4-diacetylresorcinol (2,4-DAPG) having a broad-spectrum antimicrobial activity secreted by rhizosphere-promoting bacteria Pseudomonas fluorescens, acts as a signal molecule to influence and regulate the physiological activities of some plant symbiotic bacteria. However, the exact mechanism of the sensing and response mechanisms of 2,4-DAPG and MAPG by rhizosphere-promoting bacteria is poorly understood.This project will take the rhizosphere growth-promoting bacteria Pseudomonas fluorescens Pf-5 as an model. Combining the methods of microbiology, biochemistry, molecular biology and structural biology,we will determine the signaling roles of 2,4-DAPG and MAPG by phenotype (eg. production of secondary metabolites , biofilm formation and motility) characterization. Moreover, we will investigate the response mechanism of key transcription regulators PhlF and PhlH to signal molecules and the recognition mechanism of DNA, establish a precise regulation model of PhlF and PhlH and find new downstream target genes regulated by PhlF and PhlH. The comprehensive understanding of the molecular mechanism of secondary metabolites of rhizosphere-promoting bacteria in intraspecific signaling communication provided a basic theory for the research and development of environmentally friendly biological control.