Xylella fastidiosa (Xf) is deposited into the xylem of plants
by sap-feeding leafhoppers, and can induce Pierce’s disease
of grapevine and citrus variegated chlorosis [51].
Biofilms of Xf in the insect are composed of cells that are
polarly attached to insect foregut tissue [52,53,54]. In
the plant host, most xylem vessels are sparsely colonized
and asymptomatic, whereas densely populated vessels
with biofilms are more rare, but symptomatic [54].
Colonization depends on the rpf quorum-sensing (QS)
system and the diffusible signal factor (DSF) [55].