Detection of phytoplasma diseases of apricot trees in Aydın and Denizli provinces

In Aydın, grower complaints due to sudden decline of young trees, abnormal plant growth in apricot cultivar Mikado, in 2022 and 2023, disease surveys were conducted in Aydın and Denizli provinces. Leaf and root samples were taken from trees showing phytoplasma-like disease symptoms of leafroll, chlorosis, proliferation and apparently healthy-looking trees. Besides, using yellow sticky traps, insect samples were collected from the cultivar Sakıt showing phytoplasma-like disease symptoms, located in ADÜ Faculty of Agriculture. Forty-five plant samples from 10 orchard in Aydın and thirty-eight plant samples 11 orchard in Denizli were tested by nested PCR using universal 16SrDNA and group X specific primers. Forty-nine insect samples were nested PCR tested using universal 16SrDNA primers. Phytoplasma 16Sr group and subgroups were identified with either cloning or directly bidirectional DNA sequence analysis and PCR-RFLP with AluI, RsaI ve SspI enzymes of nested PCR products. In this study, in Aydın 5 out of 10 and 8 out of 11 orchard in Denizli were found to be infested with phytoplasmas. No phytoplasma was detected in healthy-looking plant samples and insects. GenBank homology search and phylogenetic analysis of eleven 16SrDNA sequences revealed that the sequences shared 100% to 99.8% homology with European Stone Fruit Yellows (ESFY) phytoplasma 'Ca. Phytoplasma prunorum'. Real and virtual iPhyClassifier PCR-RFLP profiles of AluI, RsaI, SspI enzyme cuttings of the nested PCR products corresponded to 16Sr group X-B. Moreover, R16F2n region sequences obtained from the six root samples were identified as Bacillus sp. and Bacillus megaterium after GenBank homology search, indicating the universal primers amplified non-target gram-positive bacterial DNA. In this study, as far as we know, ESFY phytoplasmas were identified for the first time in apricot trees including the cultivars Mikado and Mogador growing in Aydın and Denizli provinces. Key words: Canditatus Phytoplasma prunorum, apricot, nested PCR, Prunus armeniaca L., 16SrDNA