Detection and Identification of Diverse Phytoplasmas in Declining Persimmon Plants

Persimmon (Diospyros kaki) plants showing yellowing, reddening, die-back, and decline symptoms were observed in Mehriz (Yazd province), Iran. Total DNAs, extracted from samples collected from symptomatic and symptomless plants, were subjected to direct and nested PCR, amplifying the 16S rRNA gene of phytoplasmas using specific primer pairs. PCR amplicons of expected lengths were obtained, mainly from nested PCR, and only from samples collected from symptomatic plants. Real and virtual RFLP, phylogenetic, and DNA identity analyses of the partial 16S rRNA gene sequences suggested the presence of diverse phytoplasmas in the analyzed samples. The identified phytoplasmas were referable to 'Candidatus Phytoplasma omanense' (16SrXXIX group) and 'Ca. P. australasiae = australasiaticum' (16SrII-D subgroup). The results of the sampling and testing highlight the urgent need for an accurate survey to verify the presence and identity of phytoplasmas in symptomatic fruit trees in Iran, in order to be able to plan appropriate management strategies. Further investigations of the possible role of 'Ca. P. omanense' strains as an emerging threat to fruit orchards in Iran should also be performed.