Five genes (rpfF, gumD, ftsZ, rrlA and glmS) were chosen to explore the effects of difficidin and bacilysin on Xanthomonas gene expression. The rpfF gene is involved in production of a diffusible signal factor (DSF)1 and the gumD gene is a gene in the gum operon responsible for extracellular polysaccharide (EPS) biosynthesis2, which are both required for virulence