Flavescence doree in France and Italy - Occurrence of closely related phytoplasma isolates and their near relationships to Palatinate grapevine yellows and an alder yellows phytoplasma

Grapevine yellows (GY) are diseases of Vitis vinifera caused by phytoplasma s. On the basis of DNA analysis, it is possible to distinguish different gr oups and subgroups among grapevine phytoplasmas. Flavescence doree (FD), th e most serious problem in European vineyards, is caused by a phytoplasma wh ich belongs to the elm yellows group (EY or 16SrV), Differences between 7 p hytoplasma isolates in this group, found until now in French, Italian and G erman grapevines, and 4 phytoplasmas in the same group, isolated mainly fro m elm and alder in Europe and America, were investigated. These 11 EY-group isolates plus 3 non-EY phytoplasmas, were compared by PCR-RFLP analyses of two different DNA fragments using 8 restriction enzymes. Two French and tw o Italian grapevine isolates, classified as FD, appeared to be closely rela ted and were also closer to an Italian alder phytoplasma. One French and on e Italian FD isolate always showed the same restriction pattern. On the opp osite, the three German grapevine isolates related to alder phytoplasmas in Germany appeared to be closer to the two elm phytoplasmas from America and Europe.