MOLECULAR-DETECTION OF DIVERSE MYCOPLASMALIKE ORGANISMS (MLOS) ASSOCIATED WITH GRAPEVINE YELLOWS AND THEIR CLASSIFICATION WITH ASTER YELLOWS, X-DISEASE, AND ELM YELLOWS MLOS

Polymerase chain reactions (PCR) and restriction analyses of PCR-amplified DNA were used to detect and differentiate strains of mycoplasmalike organisms (MLOs) associated with grapevine yellows detected in naturally diseased grapevines in the United States and Italy. At least three major groups of grapevine-infecting MLOs were delineated. FDVA1 MLO, discovered in yellows-diseased grapevines in Virginia, and flavescence doree MLO strain FDU from northern Italy were classified with X-disease MLOs; grapevine yellows-associated MLO strains FDG from Germany, CA1, CH1, SAN1, and SAN2 from northern Italy, and FDB and FDR from southern Italy were classified with aster yellows MLOs; and flavescence doree MLO strain FDF from France was classified in the elm yellows MLO group. The data support consideration of grapevine yellows as a complex of several diseases of diverse etiologies.