Identification of Flavescence dorée-related phytoplasma infecting grapevines on the isle of Ischia (southern Italy)

Abstract

Among the grapevine diseases, Flavescence dorée (FD) is considered to be one of the greatest threats for grapevine cultivation throughout Europe. In Italy, where several major outbreaks of FD have occurred in the past, the disease is still mainly restricted to the northern regions and is under mandatory regulation. In 2011 the disease was recorded for the first time in southern Italy, in several vineyards located on the isle of Ischia (Campania). In order to determine the FD-related phytoplasma infecting these grapevines, molecular investigations were carried out on grapevine samples collected from several FD infected vineyards. The 16S rDNA/spacer region and the FD9 non-ribosomal fragment (secY gene) were investigated using a PCR/RFLP based method; a nucleotide sequence analysis of the FD9 amplified fragments was also carried out. The RFLP profiles obtained from all the analyzed samples showed the presence of FD-D phytoplasma type, on both 16S and secY genomic regions. Sequencing of the FD9 fragments showed a 99 % nucleotide sequence identity among the tested isolates and the various FD-D strains retrieved from the NCBI database.