P-645 - The genetic mechanisms of plant pathogenic Ralstonia host infection

The increasing severity of plant disease threatens global food security and environmental sustainability. To effectively manage disease, it is crucial to understand how the evolution of pathogen populations contributes to their spread. Pathogen growth and reproduction in the host are key fitness traits that affect disease outcomes. However, the fitness mechanisms required for successful host colonization remain poorly understood. Here, we investigate genetic traits of plant pathogenic Ralstonia that affect host infection. We used high-throughput forward genetic screening using a random barcode transposon mutant sequencing approach to quantify the fitness of thousands of Ralstonia mutants inside the host. We inoculated tomato cv. Moneymaker plants with a library of barcoded mutants and used Illumina sequencing to measure changes in relative mutant abundance before and after growth in tomato. This approach allowed us to identify genes with diverse functions, including secretion systems, membrane transport, and motility, that are required for or challenging to Ralstonia growth. These findings will help us prioritize targets for crop resistance breeding against Ralstonia and help advance disease management practices.