Molecular characterisation of grapevine yellows associated phytoplasmas of the stolbur-group based on RFLP-analysis of non-ribosomal DNA

Grapevines, alternative host plants, and vectors from different viticultural areas of Germany were surveyed for the presence of stolbur-group phytoplasmas that are associated with grapevine yellows. Isolates from these field samples and periwinkle isolates of stolbur were characterised by RFLP-analysis of non-ribosomal DNA fragments using a combination of 6 polymorphic primer-enzyme combinations. Three of the 5 different restriction profiles that could be distinguished were found in grapevine and other field samples of plants and insects. A previously unknown isolate was detected in grapevine, vectors and the newly identified herbaceous host Calystegia sepium. The further analysis of the phylogenetic relationship between the 5 RFLP groups revealed a close relationship between two of the isolates associated with grapevine yellows which were also found in the two Convolvulaceae Convolvulus arvensis and Calystegia sepium. The third isolate which was detected in grapevine and stinging nettle Urtica dioica is more closely related to a periwinkle isolate obtained from Lavandula officinalis than to the other two grapevine yellows isolates. Based on the data of the field survey a specific association of the three isolates to different alternative host plants is discussed.