Grapevines yellows in Chile

Detection and identification of phytoplasmas associated with Chilean grapevines was performed. Symptomatic and/or asymptomatic grapevine plants were sampled and tested by nested PCR, that allows the detection of phytoplasmas in 30 out of 91 samples. Identification by RFLP analyses assigned the detected phytoplasmas to 16SrI-B, 16SrI-C, 16SrVII-A and 16SrXII-A ribosomal subgroups. Cloning and sequencing selected isolates allow the detection of genetic variability in 16SrXII-A Chilean strains. The finding of 16SrVII-A phytoplasmas is new for grapevine, while appear to be detected in different host species. Flavescence doree was not detected in Chilean grapevines. Infection with more than one type of phytoplasma is not uncommon in Chilean grapevines. Mixed infections between phytoplasmas and viruses frequently occur, that difficult the visual diagnosis. There is no evidence of epidemic spreading of yellows symptoms in the surveyed vineyards, nevertheless, future danger of 16SrXII-A epidemic spreading is not totally excluded. Survey to verify the presence and identity of insect vector or potential vector and also possible herbaceous weed hosts plants, acting as reservoir of phytoplasmas, are in progress.