شناسایی و طبقه بندی بیماری‌های فیتوپلاسمایی در مزارع سبزی و صیفی‌ استان هرمزگان

Hormozgan province is one of the main regions in producing tomatoes, eggplants, peppers, cucumbers and other vegetables in the winter season in Iran. However, the production is often adversely affected by a number of pests and diseases. Big bud and phyllody both are economically important diseases of vegetables crops in Iran. In 2017-2018, many plants with typical symptoms of phytoplasms diseases were collected from vegetable farms of Hormozgan province. The most important symptoms observed in the collected plant were including big bud, thick and upright standing stems in the tomato plants; phyllody, virescence, big bud, yellowing and little leaves in the eggplant plants; big bud, yellowing and stunting in the pepper plants and phyllody in the cucumber plants. To confirm association of phytoplasma with the symptomatic plants, the total genomic DNA was extracted from 0.2 g midribs of symptomatic and asymptomatic of each plants using modified cetyltrimethylammonium bromide (CTAB) method. The samples were tested for phytoplasma DNA by direct-PCR using the phytoplasma universal primer pair P1/P7 and nested-PCR using primers P1/P7 (first round) followed by R16F2n/R16R2 (second round). Amplicons of the expected sizes (1800 and 1250 bp) were observed in direct and nested-PCR in all symptomatic plants, respectively, but not from symptomless plant or sterile distilled water as negative controls. A nested-PCR product from each plant was directly sequenced and edited using BioEdit (v. 5.0.9). BLAST search using obtained sequences showed that the phytoplasmas associated with big bud in samples of pepper, eggplant, tomato and phyllody samples in cucumber and eggplant is belong to 16SrII group. Moreover, one of the tomato isolates showed 100 % similarity with the 16SrVI phytoplasma group. There are several reports regarding association of big bud diseases with tomato in Iran which all are closer to the members of 16SrI, VI, IX, and XII groups. To our knowledge, this is the first report of natural infection of tomato by a 16SrII phytoplasma in Iran.