This project focuses on the lipopolysaccharide (LPS) component of the outer membrane of Xylella fastidiosa (Xf). In particular, we are investigating if the O-antigen portion of this molecule contributes to Xf surface attachment and biofilm formation. More importantly, by targeting genes involved in O-antigen biosynthesis, we will determine if LPS is an important virulence factor for Xf infection of grape. Additionally, we will determine if LPS contributes to the high level of host specificity observed for this pathogen.