Detection of ‘Candidatus Phytoplasma brasiliense’ in a new geographic region and existence of two genetically distinct populations’

Abstract

‘Candidatus Phytoplasma brasiliense’, a phytoplasma taxon associated with hibiscus witches’ broom disease was first described in 2001 in Brazil. In September 2007, a peach tree (Prunus persica) displaying yellowing symptoms reminiscent of phytoplasma infection was sampled in Guba region of Azerbaijan. A phytoplasma was detected in the diseased peach tree by nested PCR amplification of its 16S rDNA with universal primers for phytoplasmas. Phylogenetical analyses of the amplified 16S rDNA showed that the phytoplasma infecting the peach tree corresponded to ‘Ca. P. brasiliense’, a species never reported in Euro-Mediterranean area. To set up a detection assay, cloning of a ‘Ca. P. brasiliense’ DNA fragment was undertaken by comparative RAPD. The amplified dnaK-dnaJ genetic locus was used to design a nested PCR assay able to amplify all ‘Ca. P. brasiliense’ isolates of the subgroup 16SrXV-A without amplifying the related members of the group 16SrII. This assay also allowed confirming the first detection of ‘Ca. P. brasiliense’ in diseased basil collected in south Lebanon.