Detection and characterization of phytoplasmas infecting grapevine in southern Italy and their genetic relatedness to other grapevine yellows phytoplasmas.
In the Campania region, southern Italy, diseased grape plants showing typical symptoms of grapevine yellows such as leaf roll, veinal yellowing and necrosis, withering of flower clusters, incomplete lignification of shoots and black pustules along the shoots, were examined for phytoplasma infection using PCR. All affected plants examined tested positive. Using specific primers and restriction fragment length polymorphism analysis of PCR-amplified ribosomal DNA sequences, the detected organism was identified as a phytoplasma of the stolbur group. Comparisons of the restriction profiles obtained following digestion with AluI, RsaI, Sau3AI, HhaI, MseI and TaqI, showed that phytoplasmas infecting grape in Campania are genetically uniform and similar to the phytoplasma causing Vergilbungskrankheit in Germany. Also, several other phytoplasmas, which were transmitted in the Emilia Romagna region by dodder from diseased grape to periwinkle (Catharanthus roseus) or collected in a vineyard and were previously classified as members of aster yellows group, were identified as stolbur phytoplasma. This is the first report on the occurrence of phytoplasmas in diseased grape in Campania.