Cyclic di-GMP Signaling in the Phytopathogen Xanthomonas campestris pv. campestris

Xanthomonas campestris pv. campestris (Pammel) Dowson (Xcc hereafter) is the causal agent of black rot of crucifers. Whole genome sequencing has revealed an abundance of GGDEF-, EAL-, and HD-GYP-domain-containing proteins in Xcc. Most GGDEF, EAL, and HD-GYP domains are linked to a wide range of signal-input domains, suggesting that numerous environmental and internal signals can be potentially integrated into the cyclic di-GMP metabolism network. This chapter summarizes these interesting findings with a focus on diffusible signaling factor (DSF)-dependent quorum sensing, RavS/RavR-dependent hypoxia sensing and the identified cyclic di-GMP effectors in Xcc.