Detection and identification of phytoplasmas in pomegranate trees with yellows symptoms.

Symptoms resembling those associated with phytoplasma presence were observed in pomegranate (Punica granatum L.) trees in June 2012 in the Aegean Region of Turkey (Aydın province). The trees exhibiting yellowing, reduced vigour, deformations and reddening of the leaves and dieback symptoms were analysed to verify phytoplasma presence. Total nucleic acids were extracted from fresh leaf midribs and phloem tissue from young branches of ten symptomatic and five asymptomatic plants. Nested polymerase chain reaction assays using universal phytoplasmaspecific 16S rRNA and tuf gene primers were performed. Amplicons were digested with Tru1I, Tsp509I and HhaI restriction enzymes, according to the primer pair employed. The phytoplasma profiles were identical to each other and to aster yellows (16SrI-B) strain when digestion was carried out on 16Sr(I)F1/R1 amplicons. However, one of the samples showed mixed profiles indicating that 16SrI-B and 16SrXII-A phytoplasmas were present when M1/M2 amplicons were digested, the reamplification of this sample with tuf cocktail primers allowed to verify the presence of a 16SrXII-A profile. One pomegranate aster yellows strain AY-PG from 16S rRNA gene and the 16SrXII-A amplicon from tuf gene designed strain STOL-PG were directly sequenced and deposited in GenBank under the Accession Numbers KJ818293 and KP161063, respectively. To our knowledge, this is the first report of 16SrI-B and 16SrXII-A phytoplasmas in pomegranate trees.