A novel phytoplasma associated with witches’ broom disease of Ligustrum ovalifolium in Turkey

Abstract

California privet (Ligustrum ovalifolium Hassk.) plants exhibiting leaf yellowing, witches’ broom, dieback and decline symptoms were observed for two years (2010–2011) in three gardens at Adana region (Turkey). DNA isolated from symptomatic and healthy plants was used to amplify 16S rDNA fragments by direct and nested-PCR. Phytoplasmas were detected in 21 symptomatic plants, out of 30 samples collected, whilst no PCR amplifications were obtained from asymptomatic plants. BLAST analysis of the 16S rDNA showed that the phytoplasma found in L. ovalifolium from Turkey, denoted as Turkish Ligustrum witches’ broom phytoplasma (TuLiWB), most closely resembled members of group 16SrII (peanut witches’ broom group) and shared up to 92 % sequence identity. Based on in silico 16S rDNA RFLP analysis and automated calculation of the pattern similarity coefficient, TuLiWB showed molecular characteristics different from all previously described phytoplasma species to represent a new taxon. Similar indication also emerged from the phylogenetic tree which allocated it in a novel discrete subclade within the phytoplasma clade. This is the first report on the presence of a phytoplasma affecting L. ovalifolium and whether this novel phytoplasma is the same agent reported as a mycoplasma-like organism (MLO) and associated with witches’ broom disease of Ligustrum in Korea (1989) is yet to be determined.