Publication Date:
2015-02-14
Description:
Mitochondrial genomes of lycophytes are surprisingly diverse, including strikingly different transfer RNA (tRNA) gene complements: No mitochondrial tRNA genes are present in the spikemoss Selaginella moellendorffii , whereas 26 tRNAs are encoded in the chondrome of the clubmoss Huperzia squarrosa . Reinvestigating the latter we found that trn L(gag) and trn S(gga) had never before been identified in any other land plant mitochondrial DNA. Sensitive sequence comparisons showed these two tRNAs as well as trn N(guu) and trn S(gcu) to be very similar to their respective counterparts in chlamydial bacteria. We identified homologs of these chlamydial-type tRNAs also in other lycophyte, fern, and gymnosperm DNAs, suggesting horizontal gene transfer (HGT) into mitochondria in the early vascular plant stem lineages. These findings extend plant mitochondrial HGT to affect individual tRNA genes, to include bacterial donors, and suggest that Chlamydiae on top of their recently proposed key role in primary chloroplast establishment may also have participated in early tracheophyte genome evolution.
Print ISSN:
0737-4038
Electronic ISSN:
1537-1719
Topics:
Biology
Permalink