Biodiv Sci ›› 2009, Vol. 17 ›› Issue (5): 476-481.DOI: 10.3724/SP.J.1003.2009.09100

• Editorial • Previous Articles     Next Articles

Intra-genomic polymorphism in the internal transcribed spacer (ITS) regions of Cycas revoluta: evidence of incomplete concerted evolution

Longqian Xiao1,2, Hua Zhu1,*()   

  1. 1 Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223
    2 Graduate University of the Chinese Academy of Sciences, Beijing 100049
  • Received:2009-04-16 Accepted:2009-09-05 Online:2009-09-20 Published:2009-09-20
  • Contact: Hua Zhu


In the present study, a high intra-genomic polymorphism was detected in the internal transcribed spacer (including ITS1, 5.8S and ITS2) regions of Cycas revoluta, suggestive of incomplete concerted evolution. Detailed comparisons of the ITS sequences from C. revoluta and those from other species further suggested that some divergent ITS paralogs from C. revoluta were likely pseudogenes. Some of these putative pseudogenes may have rather long evolutionary histories, because they have diverged substantially in sequences. We proposed that the incomplete concerted evolution in C. revoluta may have resulted from the high number and dispersed distribution of the nucleolus organizer regions (NORs) in the genome.

Key words: Cycas revoluta, nrDNA ITS, concerted evolution, pseudogenes, polymorphism