ISSN:
1432-0983
Keywords:
Key wordsCenococcum geophilum
;
Internal transcribed spacer (ITS)
;
Ribosomal DNA (rDNA)
;
Group-I intron
;
Mycorrhizae
;
RNA secondary structure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cenococcum geophilum is an ecologically important mycorrhizal fungus with a global distribution and a wide host range. It has been difficult to study since it forms only sterile mycelia and, occasionally, sclerotial bodies. Because of its lack of morphological variability, its taxonomy and phylogenetic origins have until recently remained unclear. To better understand the genetic variation and environmental adaptability of C. geophilum, a molecular phylogeny was constructed based on the nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2) of 69 isolates from various hosts and habitats. The results suggest DNA sequence conservation in the ITS regions. Considering its broad geographic and host range, this ITS conservation was unexpected. Our data imply that the ITS2 region is under evolutionary pressure to maintain the RNA secondary structure (similar to the pressure on the CgSSU introns) involved in the post-transcriptional processing of rRNA. Also, C. geophilum has very short ITS regions, thus limiting the number of mutable sites. This limited ITS variability suggests a recent radiation of C. geophilum, having been geographically distributed by a variety of efficient processes. C. geophilum appears to be a single taxonomic entity, possibly a single species. Therefore, it is an extremely adaptable, as well as ecologically valuable, taxon.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002940050449
Permalink
