ترادف نوكلئوتيدي و ويژگي هاي ساختاري دو واريانت جديد ويروئيد كوتولگي رازك از مركبات استان فارس

NUCLEOTIDE SEQUENCE AND STRUCTURAL FEATURES OF TWO NOVEL VARIANTS OF HOP STUNT VIROID cDNA FROM CITRUS PLANTS IN FARS PROVINCE

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 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 other 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 were clustered in a single group whereas Fars isolates were placed in different groups. HSVd-citl from Fars was different from all other variants and formed a separate cluster. This indicates the existence of more variations in the genome of the Fars HSVd isolates than Mazandaran isolates.