A recently presented taxonomical arrangement of the moss genus Orthotrichum Hedw. s.l. substantially changed the traditional view of the taxon that had been accepted throughout the twentieth century. This paper provides the results of mitogenomic studies that strongly support the new taxonomical concept. Comparative analyses presented in this study confirmed the stable structure of moss mitogenomes. Moreover, 17 complete mitogenome sequences were used to identify the major evolutionary groups, including 11 newly sequenced ones, for this study. The analysis of mitochondrial hotspots revealed intron 4 of the cox1 gene to be the most variable non-coding region. The most variable protein-coding genes in the tribe Orthotricheae were ccmFC and tatC. The intergenic and intronic hotspots of Orthotrichum s.l. identified in the present study do not correspond to those described in vascular plant mitogenomes.
Genes encoding ribosomal RNA (rDNA) are universal key constituents of eukaryotic genomes, and the nuclear genome harbours hundreds to several thousand copies of each species. Knowledge about the number of rDNA loci and gene copy number provides information for comparative studies of organismal and molecular evolution at various phylogenetic levels. With the exception of seed plants, the range of 45S rDNA locus (encoding 18S, 5.8S and 26S rRNA) and gene copy number variation within key evolutionary plant groups is largely unknown. This is especially true for the three earliest land plant lineages Marchantiophyta (liverworts), Bryophyta (mosses), and Anthocerotophyta (hornworts). In this work, we report the extent of rDNA variation in early land plants, assessing the number of 45S rDNA loci and gene copy number in 106 species and 25 species, respectively, of mosses, liverworts and hornworts. Unexpectedly, the results show a narrow range of ribosomal locus variation (one or two 45S rDNA loci) and gene copies not present in vascular plant lineages, where a wide spectrum is recorded. Mutation analysis of whole genomic reads showed higher (3-fold) intragenomic heterogeneity of Marchantia polymorpha (Marchantiophyta) rDNA compared to Physcomitrella patens (Bryophyta) and two angiosperms (Arabidopsis thaliana and Nicotiana tomentosifomis) suggesting the presence of rDNA pseudogenes in its genome. No association between phylogenetic position, taxonomic adscription and the number of rDNA loci and gene copy number was found. Our results suggest a likely evolutionary rDNA stasis during land colonisation and diversification across 480 myr of bryophyte evolution. We hypothesise that strong selection forces may be acting against ribosomal gene locus amplification. Despite showing a predominant haploid phase and infrequent meiosis, overall rDNA homogeneity is not severely compromised in bryophytes.
- MeSH
- Anthocerotophyta classification genetics MeSH
- Arabidopsis classification genetics MeSH
- Bryophyta classification genetics MeSH
- Chromosomes, Plant genetics MeSH
- Cytogenetic Analysis MeSH
- DNA, Plant genetics MeSH
- Species Specificity MeSH
- Phylogeny MeSH
- Gene Dosage MeSH
- In Situ Hybridization, Fluorescence MeSH
- Conserved Sequence MeSH
- Real-Time Polymerase Chain Reaction MeSH
- Hepatophyta classification genetics MeSH
- Evolution, Molecular MeSH
- DNA, Ribosomal genetics MeSH
- RNA, Ribosomal genetics MeSH
- RNA, Plant genetics MeSH
- Genes, Plant MeSH
- Embryophyta classification genetics MeSH
- Publication type
- Journal Article MeSH
The mitogenome of the Orthotrichum rogeri (GenBank accession number KM873610) has a total length of 106,634 bp and consist of 40 protein-coding genes, 3 ribosomal RNA (rRNA) and 24 transfer RNA. The gene order is identical to other known moss mitogenomes. A complete mitochondrial genome sequence of O. rogeri will help the development of primers for examining mitochondrial variation across bryophytes.
The mitogenome of Niphotrichum ericoides (GenBank accession number KP 233863) has a total length of 106,727 bp and consists of 40 protein-coding genes, three ribosomal RNAs (rRNAs), and 24 transfer RNAs. The gene order is identical to that known in other moss mitogenomes.
BACKGROUND: Bryophytes represent a very diverse group of non-vascular plants such as mosses, liverworts and hornworts and the oldest extant lineage of land plants. Determination of endogenous phytohormone profiles in bryophytes can provide substantial information about early land plant evolution. In this study, we screened thirty bryophyte species including six liverworts and twenty-four mosses for their phytohormone profiles in order to relate the hormonome with phylogeny in the plant kingdom. METHODOLOGY: Samples belonging to nine orders (Pelliales, Jungermanniales, Porellales, Sphagnales, Tetraphidales, Polytrichales, Dicranales, Bryales, Hypnales) were collected in Central and Northern Bohemia. The phytohormone content was analysed with a high performance liquid chromatography electrospray tandem-mass spectrometry (HPLC-ESI-MS/MS). PRINCIPAL FINDINGS: As revealed for growth hormones, some common traits such as weak conjugation of both cytokinins and auxins, intensive production of cisZ-type cytokinins and strong oxidative degradation of auxins with abundance of a major primary catabolite 2-oxindole-3-acetic acid were pronounced in all bryophytes. Whereas apparent dissimilarities in growth hormones profiles between liverworts and mosses were evident, no obvious trends in stress hormone levels (abscisic acid, jasmonic acid, salicylic acid) were found with respect to the phylogeny. CONCLUSION: The apparent differences in conjugation and/or degradation strategies of growth hormones between liverworts and mosses might potentially show a hidden link between vascular plants and liverworts. On the other hand, the complement of stress hormones in bryophytes probably correlate rather with prevailing environmental conditions and plant survival strategy than with plant evolution.
- MeSH
- Bryophyta classification metabolism MeSH
- Cyclopentanes analysis metabolism MeSH
- Cytokinins analysis metabolism MeSH
- Phylogeny MeSH
- Spectrometry, Mass, Electrospray Ionization MeSH
- Abscisic Acid analysis metabolism MeSH
- Salicylic Acid analysis metabolism MeSH
- Indoleacetic Acids analysis metabolism MeSH
- Oxylipins analysis metabolism MeSH
- Plant Growth Regulators analysis metabolism MeSH
- Chromatography, High Pressure Liquid MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
