A transcriptome study of DSF-mediated quorum sensing in Xanthomonas axonopodis pv. citri

Quorum sensing (QS) in Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is mediated by a diffusible signal factor (DSF). QS is required for the full virulence of X. axonopodis pv. citri in planta. Mutations in rpfF, rpfC and rpfG, the core genes of QS, decreased the production of extracellular proteases and bacterial motility. Comparison of the transcriptomes of QS mutants with that of the wild type stain revealed that QS temporally regulates the expression of a large set of genes, including genes involved in chemotaxis and flagellar biosynthesis, genes related to metabolism, genes encoding virulence traits such as type II secretion system substates, type III secretion system and effectors. Cross talk between the QS regulon and the HrpG regulon has also been identified by 62 common genes shared by both regulons. The temporal regulation of the QS regulon and cross talk with the HrpG regulon suggest the important role of QS in citrus canker infection, including attachment, invasion and growth in host apoplast. Three mutants and two time-points experiment. Four biological and dye-swap replicates of each strain per each time-point were used. In total, there were two datasets of the rpfF mutant: 1) rpfF mutant vs. wild type strain at 11 h, and 2) rpfF mutant vs. wild type strain at 25 h; two datasets of the rpfC mutant: 1) rpfC mutant vs. wild type strain at 11 h, and 2) rpfC mutant vs. wild type strain at 25 h; and two datasets of the rpfG mutant: 1) rpfG mutant vs. wild type strain at 11 h, and 2) rpfG mutant vs. wild type strain at 25 h.