In planta bacterial multi-omics illuminates regulatory principles underlying plant-pathogen interactions

Gene regulation of bacterial pathogens in the host is not comprehensively understood due to the difficulty in analyzing genome-wide mRNA and protein expression of bacteria during infection. Here, we jointly analyzed transcriptome and proteome of a foliar bacterial pathogen in plants. Bacterial transcriptome changes can explain to a large extent their proteome changes in resistant and susceptible plants. However, a part of bacterial type III secretion system was suppressed by plant immunity preferentially at the protein level. Also, gene co-expression analysis uncovered previously unknown gene regulatory modules underlying bacterial virulence. Collectively, integrated in planta bacterial omics provides molecular insights into multiple layers of bacterial gene regulation that contributes to virulence and roles of plant immunity in controlling it.