Total RNA was isolated from phloem of young shoots and retro-transcripted to cDNA by RT-PCR(Reverse Transcriptase-Polymerase Chain Reaction) with specific primer pair of CVd-Ⅲ (citrus viroid-Ⅲ), the results of molecular detection indicated that the CVd-Ⅲ specific bands, about 300 bp, were detected in 27 of the 49 samples collected from different counties in Hunan Province and 1 sample presented by Catania University. All the amplified cDNA fragments were cloned and sequences, sequence analysis compared with the reported CVd-Ⅲ sequences in GenBank showed that: sequences of 21 samples were the same and completely identical with CVd-Ⅲb (AF184147); however, the sequences of the other 6 samples and presented sample were diversified from the reported CVd-Ⅲ sequences in GenBank.
