Different hypotheses have been proposed to interpret the observed unusual ITS (internal transcribed spacer) sequences in Ophiocordyceps sinensis. The coexistence of diverged ITS paralogs in a single genome was previously shown by amplifying the ITS region from mono-ascospore isolates using specific primers designed for different ITS paralog groups. Among those paralogs, are AT-biased ITS sequences which were hypothesized to result from repeat-induced point mutation (RIP). This is a process that detects and mutates repetitive DNA and frequently leads to epigenetic silencing, and these mutations have been interpreted as pseudogenes. Here we investigate the occurrence and frequency of ITS pseudogenes in populations of O. sinensis using large-scale sampling, and discusses the implications of ITS pseudogenes for fungal phylogenetic and evolutionary studies. Our results demonstrate a wide distribution of ITS pseudogenes amongst different geographic populations, and indicate how ITS pseudogenes can contribute to the reconstruction of the evolutionary history of the species.
Bibliographical noteFunding Information:
This work is supported by the National Natural Science Foundation of China (31400018, 30025002), the Ministry of Science and Technology of China (2012CB126308, 2012FY111600, 2013BAD16B01) and the Chinese Academy of Sciences (KSCX2-YW-G-076, KSCX2-YW-G-074-04, KSCX2-SW-101C and the scheme of Introduction of Overseas Outstanding Talents).
- Caterpillar fungus
- Cordyceps sinensis
- ITS pseudogene
PubMed: MeSH publication types
- Journal Article