同源重组是细菌进化的“快车道”，在细菌生存和进化过程中发挥重要作用。前期研究提示细菌同源重组会受到自然选择影响，但目前仍缺乏对细菌同源重组进化推动力的全面认识，细菌同源重组进化的动态变化规律尚不清楚。副溶血弧菌是常见的食源性病原菌，也是高频同源重组细菌的代表物种，可作为细菌同源重组进化研究的理想模型。本项目拟对长时间跨度（2002年至今）的500株具有代表性的副溶血弧菌大流行株开展第二、三代全基因组测序，解析大流行株的种群结构；联用多种方法鉴定同源重组事件，构建大流行株同源重组的特征图谱；从同源重组热区、上位相互作用模式、趋同进化、功能影响和相关基因选择压力等角度阐述同源重组的进化推动力；从时间、空间维度解析同源重组进化的动态变化规律，揭示同源重组在副溶血弧菌大流行株进化中的作用。本项目将进一步明确副溶血弧菌同源重组的进化动力学规律，为其它高频重组细菌的进化研究提供新参考。

Homologous recombination is the "highway" of bacterial evolution, which plays an important role in the survival and evolution of bacteria. Previous studies suggested that bacterial homologous recombination can be affected by natural selection, but currently there is a lack of comprehensive understanding of the evolutionary driving force of bacterial homologous recombination, and the evolutionary dynamics of bacterial homologous recombination remains unclear. Vibrio parahaemolyticus is a common foodborne pathogen, and the representative species of high-frequency homologous recombining bacteria, which can be used as an ideal model for the evolutionary study of bacterial homologous recombination. This project intends to sequence 500 representative V. parahaemolyticus pandemic strains over a long time span (2002 to present) using the second- and third-generation whole-genome sequencing technology, to construct the population structure of pandemic strains; combine multiple methods to identify homologous recombination events and describe the landscape of homologous recombination in pandemic strains; decipher the evolutionary driving force of homologous recombination from the perspectives of homologous recombination hotspots, epistatic interaction patterns, convergent evolution, impact on function and selective pressure of associated genes; clarify the evolutionary dynamics of homologous recombination by integrating temporal and spatial information, and reveal the role of homologous recombination in the evolution of V. parahaemolyticus pandemic strains. This project will further clarify the evolutionary dynamics of homologous recombination in V. parahaemolyticus, and provide a new reference for the evolutionary studies of other high-frequency recombining bacteria.