Molecular Characterization of Peach Latent Mosaic Viroid Variants Isolated From Stone Fruit Trees in Kurdistan Province, Iran

In order to investigate the possible presence and molecular features of Peach Latent Mosaic Viroid (PLMVd) in west Iran (Kurdistan Province), a total of 132 leaf samples from almond, apricot, nectarine, peach, plum, sour cherry, and sweet cherry were collected from orchards during the summer of 2016 and 2017. Reverse transcription-polymerase chain reaction amplified an expected ~350 base pair DNA fragment from 34 samples. The complete genome sequencing of 17 cloned isolates was determined. Sequence alignment of the new sequences showed 94.3-100% nucleotide identity, and 79.2-100% nucleotide identity with other previously reported PLMVd isolates. In phylogenetic analysis, isolated viroid variants from this study and 32 previously reported isolates were placed in two groups (I and II). All the isolated viroid variants in the present study were placed in group II-A (mosaic-inducing isolates), together with other isolates from Australia, China, India, Iran, Spain, Tunisia, and Turkey. The secondary structure of the Iranian variants revealed their unique structures as compared with previously reported isolates of the viroid. To our knowledge, this is the first report of PLMVd infection on apricot, sweet cherry, sour cherry, and nectarine in Iran.