Abstract: In this study, PCR amplification of nrDNA ITS of Camellia was improved by the addition of DMSO in PCR protocol, the sequence characteristic of ITS were analyzed. The results showed that: (1)The PCR amplification efficiency of ITS was improved by the addition of 4% DMSO, and the ITS pseudogenes were prevented from being amplified; (2)ITS pseudogenes exhibited a significant deletion in ITS1 and ITS2 region, and displayed lower GC content and unstable secondary structure; (3)ITS pseudogenes could not provided the real phylogenetic relationships, it showed the necessity of great care when used the ITS sequence in evolutionary studies in genus Camellia.

Key words: DMSO, ITS, Camellia, pseudogene