Abstract
Phytophthora infestans causes potato late blight and significantly impacts potato production. The pathogen's remarkable adaptability and ability to generate new physiological races through virulence variation undermine varietal resistance, posing challenges for disease prevention and control. To explore the genetic mechanisms behind these, different physiological races of P. infestans were inoculated on potato leaves and assayed through transcriptomics combined with metabolic profiling methods. It was found that the DL04 strain, which carries virulence factor 3, exhibited a high level of pathogenicity. Biologically, DL04 showed more rapid growth and denser mycelial structures compared to most other strains, indicating enhanced pathogenicity. DL04 induced a greater enrichment of carbon metabolism, biosynthesis of amino acids, and glycolysis/gluconeogenesis pathways during the infection process. This led to the upregulation of genes related to cell hydrolysis, accelerating leaf infection and contributing to its higher level of pathogenicity. The reasons for the differences in pathogenicity among different physiological races of P. infestans were clarified at the transcriptional level. This finding provides valuable insights into the genetic basis of P. infestans pathogenicity and offer critical information for developing effective control strategies, breeding for disease resistance, and improving potato production practice.