Xylella fastidiosa (Xf) is a fastidious, xylem-inhabiting, Gram-negative bacterium that causes serious plant diseases in a wide range of plant species. The most serious diseases are Pierce's Disease (PD) of grape and Citrus Variegated Chlorosis (CVC). Functional genomic analyses of Xf have been severely limited by lack of a stable replicative shuttle vector. Plamsid pUFR047, small, stable, wide host range, conjugative and repW shuttle vector have been successfully transferred into Xf strains by electroporation. The vector replicated in a stable manner for over thirty generations of growth in the absence of antibiotic selection in Xf strains.