B) Role of di-Cylcic GMP as intracellular signaling molecule in plant pathogens
Recent advances in plant-pathogen interaction as elucidated the role of cyclic di-GMP as an intracellular signaling molecule which couples extracellular quorum sensing signal and is involved in variety of process like-Biofilm formation, motility, quorum sensing and regulation of virulence gene expression (Fig. 2). Three protein domains-HD-GYP, GGDEF and EAL have been implicated in the synthesis and degradation of di-Cyclic GMP (Fig. 3). Genome analysis indicates that various Xanthomonas have proteins with potential di-Cyclic GMP modulating activity.
Interestingly several two component signal transduction systems have the di-cyclic GMP modulating domains, role of these in virulence and adaptation inside the plant will give us understanding of how pathogens couples different extracellular signals with physiological adaptation to different environment (Fig. 3).