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Poster: Biology & Disease Mgmt: Bacteriology


Virulence traits and disease development by Xylella fastidiosa are impaired in a mutant on the outer membrane protein MopB
H. CHEN (1), P. Kandel (1), L. Cruz (1), L. De La Fuente (1) (1) Auburn university, U.S.A.

Outer membrane (OM) proteins are key elements to maintain the integrity of the outer membrane, and play an important role in bacterial behavior. MopB is a major OM protein in the plant pathogen X. fastidiosa, which causes major losses on many economically important crops due to occlusion of the xylem network in plants. Based on DNA sequence analysis of the gene encoding MopB, the C-terminal part is a homologue of the OmpA family, and includes a conserved calcium binding motif. However the function of MopB protein in X. fastidiosa remains poorly understood. Here, MopB function has been studied by site-directed mutagenesis. Taking advantage of the natural competence of X. fastidiosa, mopB mutants were obtained in two different X .fastidiosa strains, the type strain ‘Temecula’ and the more aggressive ‘WM1-1’. mopB mutants in both background strains were impaired in surface attachment, biofilm formation, twitching motility and natural competence. Further analysis of the bacterial surface showed that the mopB mutants were impaired in pilus formation as observed by electron microscopy. Additionally, mopB mutants in both backgrounds showed reduced virulence as compared to WT when tested on tobacco (Nicotiana tabacum) plants as a host under greenhouse condition. These results suggest that MopB has an effect on pilus biogenesis and is important for the virulence of X. fastidiosa.