Molecular Study of a New Disease of Peach in Iran Associated with a Phytoplasma

Abstract

In recent years, a disease has been reported to affect peach trees in Kurdistan province of Iran causing serious losses to the production. Main symptoms of disease include leaf stunting and yellowing, which lead to failure in fruit production at harvest. For diagnosis of disease and identification of the causal agent, s ymptomatic leaf samples were collected in Kurdistan orchards during summer 2010 and were carried to the laboratory. Total DNA was extracted from plant samples according to the standard procedures and indexed by grafting and nested PCR using phytoplasma generic primers, P1/P7 and R16F2n/R2. PCR products were characterized by RFLP technique and direct sequencing. The 16S rDNA sequences were compared with those of other phytoplasmas in GenBank. Phytoplasma rDNA was amplified from 20 out 35 samples. The 16S rDNA sequences of the phytoplasma w ere identified in Peach samples which showed 98% similarity to that of “ Candidatus Phytoplasma phoenicium ” which is considered to be the causal agent of Almond witches’ broom. Phylogenetic analysis of 16S rDNA sequences placed peach strains in Almond witches broom isolate as a member of pigeon pea witches broom (PPWB) group. Further studies on the epidemiology of “ Ca. Phytoplasma phoenicium ” and its vector(s) in Iran are recommended in order to identify new natural hosts and develop successful disease management programs.