شناسائی فیتوپلاسماهای همراه زوال زردآلو در استان خراسان رضوی

Given the importance of horticulture as Iran agricultural economy and based on relative advantages of horticultural crops compare to other crops, cultivation development and export of the horticulture products is important.The lack of water in Khorassan provicehas given the gardens a relative advantage. One the most important apricot-growing area is Razavi-Khorassan province. A total Khorasa area of cultivated apricot approximately 4300 ha and production of fresh fruit is 4 tons per years 'Shahroodi' and 'Lasjerdi' are the main native apricot varieties grown for dry and fresh consumption.During field survey in 2015-2016 of apricot orchards in Mahvelat and Khaf regions of Razavi-Khorassan province were observed apricot decline. Trees exhibit foliar yellowing, accompanied by leaf rolling, followed by marginal brown necrosis, premature and small leaf and often even fruit dropping are the most common symptoms on apricot trees, growth depression, premature autumn discoloration. Drought condition and hot temperature speed up symptom developments.Symptoms and deaths of apricot trees were observed sporadically in orchards .Affected plants usually die within a year or two.Nucleic acid samples from leaf plants showing decline symptoms were collected and molecular analyses were carried out to verify phytoplasma presence and preliminary identify by RFLP analyses on R16F2n/R2 and R16(I)F1/R1 to obtained after nested PCR on P1/P7 amplicons. Identification of detected phytoplasmas was done by RFLP analyses on 100 to 200 ng DNA of amplicons with Tru1I, TaqI, RsaI and HhaIrestriction enzymes (Fermentas, Vilnius, Lithuania) according to the manufacturer’s instructions. The digested DNA fragments were separated by electrophoresis in a 6.7% polyacrylamide gel and stained with ethidium bromide.The most samples were positive in nested-PCR and phytoplasma detected could be affiliated to ribosomal groups 16SrXII-A phytoplasmas (“stolbur”), in a few cases these profiles were mixed with those of 16SrI-B (aster yellows) phytoplasmas .The first detection of these pathogens in the same species represents a big threat not only for the Iranian apricot cultivation, but also for agriculture in general, considering that all of them are infecting a high number of plant species.