Direct nucleotide sequencing of citrus exocortis viroid (CEV)

Citrus exocortis viroid (CEV). the causal agent of bark shelling disease in Poncirus trifoliate (L.) Raf. can be distinguished by its biological properties in Etrog citron and Gynura aurantiaca D.C. CEV isolate obtained from citrus trees of Çukurova region was reverse transcribed and subsequently amplified in vitro from total nucleic acid extracts of infected tissues using a reverse transcription-polymerase chain reaction assay (RT-PCR). The amplified products were gel purified, and subsequently sequenced without cloning, using the Promega fmol sequencing system. Both CEVc (citron) and CEVg (Gynura) were determined 371 nucleotides (nts) in length. Comparing the nucleotide sequence of CEV isolate from Çukurova region and California isolates of CEV, a number of exchanges were found in the pathogenic and variable domains