Rhizobacterial biocontrol of potato late blight and genomic insights into disease suppression and growth promotion.

Late blight caused by Phytophthora infestans remains a major challenge to sustainable potato production. In this study, we evaluated five bacterial strains for their ability to reduce late blight and improve potato growth under field, in vitro, detached-leaf, and greenhouse conditions. All tested strains reduced disease severity, with Serratia rubidaea AV10 showing particularly strong antagonistic activity and consistent suppression of disease. Genome sequencing of the two potato-associated strains, AV10 and S. rubidaea EV23, revealed biosynthetic clusters and genes potentially linked to antimicrobial activity, siderophore production, biofilm formation, nutrient acquisition, and plant growth promotion. Bacterial treatment also influenced the expression of potato genes associated with jasmonic acid, ethylene, salicylic acid-related defense, and auxin-linked growth response. Together, these findings identify AV10 and EV23 as promising rhizobacterial candidates for integrated late blight management and provide genomic insight into traits that may contribute to disease suppression and plant growth promotion.