Overview of the Hrc, Hrp and Hpa genes from the Hrp cluster in X. fuscan pv. fuscans along with a structural model of the TTSS from X. campestris pv. campestris. The function identity of the genes in X. fuscans subs. fuscans is inferred from sequence homology with other Xanthamonads (Darsonoval et al., 2008). The genes in the Hrp cluster are associated with the type III secretion system which is used to inject effector molecules into the host cell.