شناسایی فیتوپلاسمای همراه با جاروک و ریز برگی بید مجنون و جاروک سنجد در استان خراسان رضوی

Salix babylonica (weeping willow) and Elaeagnus angustifolia (Russian olive) are common species used in urban green spaces and parks. Both species have shown a wide range of ecological tolerance and have adapted to different ecological niches. During the summer visits in 2023, symptoms such as stunting, leaf scaling, yellowing, witch's broom, dieback and general decay were observed in some trees of Salix babylonica and Elaeagnus angustifolia in the green area of Ferdowsi University of Mashhad in Khorasan Razavi province. Total DNA was extracted from these samples and Nested-PCR with universal primers P1/P7 and nested primers R16F1/R16R0 and R16mF2/Ru3 was used to detect phytoplasmas in Salix babylonica and Elaeagnus angustifolia, respectively. The PCR product was extracted from the agarose gel after electrophoresis using the Favorgen protocol and sequenced. The final sequences were deposited in Genbank under accession number PP830930 for the phytoplasma associated with Salix babylonica witch's broom. and PP814977 for the phytoplasma associated with Elaeagnus angustifolia witch's broom. The sequenced fragments were subjected to phylogenetic analysis together with other similar phytoplasma sequences in Genbank, and the virtual RFLP of the PCR product was also analyzed using the online program iPhyClassifier. A fragment of about 1300 base pairs was amplified in all symptomatic samples, whereas this fragment was not amplified in the DNA extracted from asymptomatic plants. A blast search of the sequenced fragment in Genbank showed that the phytoplasma associated with witch's broom of Salix babylonica and Elaeagnus angustifolia had 99% similarity to the Aster yellows phytoplasma (16SrI). In the phylogenetic tree constructed using MEGA7 software, the phytoplasma associated with witch's broom of Salix babylonica and Elaeagnus angustifolia was assigned to the 16SrI phytoplasma group. The in silico RFLP obtained from the amplified fragments of Salix babylonica and Elaeagnus angustifolia showed the highest similarity to subgroup B of the 16SrI phytoplasma with a similarity coefficient of 0.94 (accession no. AP006628). Therefore, considering the existing criteria and the RFLP similarity coefficient of 0.97 or less, this strain is a new subgroup within the 16SrI phytoplasma group.