Detection and molecular characterization of Peach latent mosaic viroid (((PLMVd) in almond (Prunus dulcis Mill.) and walnut (Juglans regia L.) growing areas in Malatya, Elazig and Adiyaman provinces (Turkey)

Survey studies were conducted to investigate the presence of Peach latent mosaic viroid (PLMVd) infections in almond and walnut production areas of Malatya, Elazig and Adiyaman provinces between 2019-2020. A total of 530 leaf samples were randomly collected in almond and walnut orchards and total RNA were extracted. Reverse transcriptase polymerase chain reaction (RT-PCR) method was implemented to investigate the presence of PLMVd infections in collected samples. PLMVd was not detected in any of the almond samples tested by RT-PCR method. Among the walnut samples tested, the presence of PLMVd was identified in all of the samples taken from the Hekimhan district of Malatya province (10 samples, H isolates) and in only one sample taken from Keban district of Elazığ province (25 samples, K1 isolate). The purified recombinant plasmids were bidirectionally sequenced with universal SP6 and T7 primers, and the obtained PLMVd sequences were overlaped with the help of CLC Mainworkbench program and editid manually. According to the consensus sequences, PLMVd-K1 (MW294170), -H1 (MW294171), -H2 (MW294172) and -H3 (MW294173) isolates were found to be 338 bp in length. In RNA folding analyses, it was observed that all four detected PLMVd-walnut isolates formed a branched secondary structure, as did the reference PLMVd isolate (M83545). It was determined that PLMVd isolates detected in walnuts showed similarity between 96.7-99.1% with the nucleotide sequences of 20 different PLMVd isolates detected in different geographical regions of the world. With this study, the PLMVd was identified for the first time in the walnut production areas of Malatya-Hekimhan and Elazig provinces.