عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Hop stunt viroid (HSVd) isolates have been reported as a causal agent of citrus cachexia in Mazandaran province and recently shown to be associated with yellow corky vein disease of sweet orange and split bark disorder of sweet lime in the Fars province. These observations indicate the importance of this viroid in citrus cultivations in Iran. In this study a number of symptomless citrus trees were sampled and studied for viroid infection. After RNA extraction, reverse transcription-polymerase chain reaction was conducted and the full length genomes of viroids were cloned and sequenced. Three HSVd isolates from Fars were selected and used for comparison with another two HSVd variants from Fars, two HSVd isolates from Mazandaran, and a number of other sequences from GenBank. On the basis of homology, Mazandaran isolates clustered in a single group whereas Fars isolates were placed in different groups. HSVd-cit1 from Fars was different from all other variants and formed a separate cluster. This indicates the exictence of more variation in the genome of the Fars HSVd isolates than Mazandaran isolates.