DIVERSITY AMONG MYCOPLASMA-LIKE ORGANISMS INDUCING GRAPEVINE YELLOWS IN FRANCE

As antibodies and molecular probes which were previously obtained for diagnosis of grapevine flavescence doree (FD; a yellows disease induce d by a MLO), showed to be highly specific, a survey of grapevine sampl es collected in different viticultural areas in France was undertaken, using a PCR method with primers allowing amplification of a part of t he 16S rRNA gene of most MLOs, and restriction analyses of the amplifi ed products (AHRENS and SEEMULLER 1992). The presence of MLO was estab lished in all the different grapevine samples, and their diversity was demonstrated. The typcial pattern yielded by FD sensu stricto-MLO was found in samples from southern vineyards, including a symptomless roo tstock. Two different patterns were found in samples affected by bois noir disease of northern French vineyards, one of these patterns being previously undescribed. The present survey was non exhaustive and sho uld be followed in the frame of a large collaboration between viticult ural countries. It showed the diversity in causal agents of diseases w hich converge in symptomatology, and emphasizes on the need of specifi c diagnosis tools, for identification of each of the vector species, f or epidemiological studies, and availability of planting material.