Bois noir phytoplasma variability in a Mediterranean vineyard system: new plant host and putative vectors

The presence of Bois noir phytoplasma (BNp, Stolbur, 16SrXII-A) in Sicily, one of themost important Italian grape-producing regions, has been known since 1996, but itsepidemiology and distribution in the region have been studied only recently.Grapevines and weeds showing symptoms of phytoplasma infection were collected inan organic Chardonnay vineyard, chosen as model vineyard, and tested to verify BNppresence. Leaf- and plant-hoppers were also captured in the same field and includedin the analysis. Plant and insect infections were assessed by nested PCR withuniversal and group-specific (16SrI and -V) phytoplasma primer pairs. BNp wasdetected in the weed species Erigeron bonariensis, which was then determined as anew natural host of this phytoplasma, and in several Auchenorrhyncha species besidesHyalestes obsoletus, which can be regarded as new potential vectors. To furtherevaluate the genetic variability of BNp among host plants and potential vectors, PCRRFLPof the Stolbur phytoplasma-specific vmp1 gene was carried out. The V1 profilewas the most representative, other profiles (V4, V9, V10 and V11) were also detected.