Identification of a group 16SrIX "Candidatus Phytoplasma phoenicium' phytoplasma associated with sweet orange exhibiting decline symptoms in Iran

During a survey in an orange (Citrus sinensis) garden in the south of the Kerman province of Iran, some trees were observed showing symptoms of yellowing and decline. Nested PCR analysis using phytoplasma universal primers identified symptomatic samples as phytoplasma-positive, whereas the symptomless samples gave no PCR products. Sequence similarity and phylogenetic studies using 16S rRNA gene sequences demonstrated that the sweet orange decline associated phytoplasma belongs to the 16SrIX Candidatus Phytoplasma phoenicium' group. To the best of the authors' knowledge this is the first report of association of a phytoplasma belonging to the Candidatus Phytoplasma phoenicium' group with decline symptoms in sweet orange in Iran.