Bryophyte Dotaz Zobrazit nápovědu
Species richness is influenced by a nested set of environmental factors, but how do these factors interact across several scales? Our main aim is to disentangle the relative importance of environmental filters and the species pool on the richness of epiphytic bryophytes across spatial scales. To do so, we sampled epiphytic bryophytes in 43 oak forests across the northwest of the Iberian Peninsula. As predictors we used climate, descriptors of forest structure and micro-environment. We applied structural equation modeling to relate these variables with richness and cover at three scales: locality (forest), stand (three stands per forest), and sample (a quadrate in a tree). We assumed top-down relationships, so that large-scale variables influenced lower scale variables, and in which cover directly influenced richness. Richness at the next larger scale (locality to stand and stand to sample) is considered a surrogate of the species pool and included as a predictor of richness at the next smaller scale. Environmental variables explain locality richness, but as we decrease the spatial scale, its importance decreases and the dependence on species pool increases. In addition, we found unexpected bottom-up relationships (between micro-scale environment to locality richness). Our results point to the scale dependence of niche vs. neutral processes: niche processes are important at the locality (forest) scale, while neutral processes are significant at the small (sample) scale. We propose a modified conceptualization of the factors influencing biodiversity at different spatial scales by adding links across different scales (between micro-environment and locality-scale richness in our study).
- MeSH
- biodiverzita MeSH
- Bryophyta * MeSH
- ekosystém * MeSH
- stromy MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
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 klasifikace metabolismus MeSH
- cyklopentany analýza metabolismus MeSH
- cytokininy analýza metabolismus MeSH
- fylogeneze MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- kyselina abscisová analýza metabolismus MeSH
- kyselina salicylová analýza metabolismus MeSH
- kyseliny indoloctové analýza metabolismus MeSH
- oxylipiny analýza metabolismus MeSH
- regulátory růstu rostlin analýza metabolismus MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
While the effects of contemporaneous local environment on species richness have been repeatedly documented, much less is known about historical effects, especially over large temporal scales. Using fen sites in the Western Carpathian Mountains with known radiocarbon-dated ages spanning Late Glacial to modern times (16 975-270 cal years before 2008), we have compiled richness data from the same plots for three groups of taxa with contrasting dispersal modes: (1) vascular plants, which have macroscopic propagules possessing variable, but rather low, dispersal abilities; (2) bryophytes, which have microscopic propagules that are readily transported long distances by air; and (3) terrestrial and freshwater mollusks, which have macroscopic individuals with slow active migration rates, but which also often possess high passive dispersal abilities. Using path analysis we tested the relationships between species richness and habitat age, area, isolation, and altitude for these groups. When only matrix-derived taxa were considered, no significant positive relation was noted between species richness and habitat size or age. When only calcareous-fen specialists were considered, however, habitat age was found to significantly affect vascular plant richness and, marginally, also bryophyte richness, whereas mollusk richness was significantly affected by habitat area. These results suggest that in inland insular systems only habitat specialist (i.e., interpatch disperser and/or relict species) richness is influenced by habitat age and/or area, with habitat age becoming more important as species dispersal ability decreases.
- MeSH
- biodiverzita MeSH
- časové faktory MeSH
- demografie MeSH
- druhová specificita MeSH
- měkkýši klasifikace MeSH
- mokřady MeSH
- mykorhiza MeSH
- rostliny klasifikace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
: Jasmonic acid (JA) and its related derivatives are ubiquitously occurring compounds of land plants acting in numerous stress responses and development. Recent studies on evolution of JA and other oxylipins indicated conserved biosynthesis. JA formation is initiated by oxygenation of α-linolenic acid (α-LeA, 18:3) or 16:3 fatty acid of chloroplast membranes leading to 12-oxo-phytodienoic acid (OPDA) as intermediate compound, but in Marchantiapolymorpha and Physcomitrellapatens, OPDA and some of its derivatives are final products active in a conserved signaling pathway. JA formation and its metabolic conversion take place in chloroplasts, peroxisomes and cytosol, respectively. Metabolites of JA are formed in 12 different pathways leading to active, inactive and partially active compounds. The isoleucine conjugate of JA (JA-Ile) is the ligand of the receptor component COI1 in vascular plants, whereas in the bryophyte M. polymorpha COI1 perceives an OPDA derivative indicating its functionally conserved activity. JA-induced gene expressions in the numerous biotic and abiotic stress responses and development are initiated in a well-studied complex regulation by homeostasis of transcription factors functioning as repressors and activators.
- MeSH
- chloroplasty metabolismus MeSH
- cyklopentany metabolismus MeSH
- druhová specificita MeSH
- kyselina alfa-linolenová metabolismus MeSH
- Marchantia metabolismus MeSH
- mastné kyseliny metabolismus MeSH
- mechy metabolismus MeSH
- metabolické sítě a dráhy MeSH
- nenasycené mastné kyseliny metabolismus MeSH
- oxylipiny metabolismus MeSH
- peroxizomy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Quadrulella (Amoebozoa, Arcellinida, Hyalospheniidae) is a genus of testate amoebae with unmistakable morphology, which secretes characteristic square plates to reinforce the test. They are mainly known from fens and freshwater habitats and have never been documented in deserts. We describe a new species, Quadrulella texcalense, from biological soil crusts in the intertropical desert of Tehuacán (state of Puebla, Mexico). Quadrulella texcalense occurred only at altitudes between 2140 and 2221m.a.s.l., together with the bryophyte genera Pseudocrossidium, Weissia, Bryum, Didymodon, Neohyophyla and Aloina. The soil was extremely dry (moisture of 1.97-2.6%), which contrasts sharply with previous reports for the Quadrulella genus. Single cell mitochondrial cytochrome oxidase I (COI) barcoding of thirteen isolated cells showed an important morphological variability despite having all the same COI barcode sequence. Quadrulella texcalense was placed in a tree containing other Hyalsopheniidae, including a newly barcoded South African species, Q. elegans. Q. texcalense unambiguously branched within genus Quadrulella in a compact clade but with a long branch, suggesting accelerated evolution due to a transition towards a new environment and/or under-sampling.
- MeSH
- druhová specificita MeSH
- fylogeneze * MeSH
- Lobosea klasifikace cytologie genetika MeSH
- pouštní klima * MeSH
- půda parazitologie MeSH
- respirační komplex IV genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Mexiko MeSH
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 klasifikace genetika MeSH
- Arabidopsis klasifikace genetika MeSH
- Bryophyta klasifikace genetika MeSH
- chromozomy rostlin genetika MeSH
- cytogenetické vyšetření MeSH
- DNA rostlinná genetika MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- genová dávka MeSH
- hybridizace in situ fluorescenční MeSH
- konzervovaná sekvence MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- Marchantiophyta klasifikace genetika MeSH
- molekulární evoluce MeSH
- ribozomální DNA genetika MeSH
- RNA ribozomální genetika MeSH
- RNA rostlin genetika MeSH
- rostlinné geny MeSH
- vyšší rostliny klasifikace genetika MeSH
- Publikační typ
- časopisecké články MeSH
The diverse forms of today's dominant vascular plant flora are generated by the sustained proliferative activity of sporophyte meristems at plants' shoot and root tips, a trait known as indeterminacy [1]. Bryophyte sister lineages to the vascular plants lack such indeterminate meristems and have an overall sporophyte form comprising a single small axis that ceases growth in the formation of a reproductive sporangium [1]. Genetic mechanisms regulating indeterminacy are well characterized in flowering plants, involving a feedback loop between class I KNOX genes and cytokinin [2, 3], and class I KNOX expression is a conserved feature of vascular plant meristems [4]. The transition from determinate growth to indeterminacy during evolution was a pre-requisite to vascular plant diversification, but mechanisms enabling the innovation of indeterminacy are unknown [5]. Here, we show that class I KNOX gene activity is necessary and sufficient for axis extension from an intercalary region of determinate moss shoots. As in Arabidopsis, class I KNOX activity can promote cytokinin biosynthesis by an ISOPENTENYL TRANSFERASE gene, PpIPT3. PpIPT3 promotes axis extension, and PpIPT3 and exogenously applied cytokinin can partially compensate for loss of class I KNOX function. By outgroup comparison, the results suggest that a pre-existing KNOX-cytokinin regulatory module was recruited into vascular plant shoot meristems during evolution to promote indeterminacy, thereby enabling the radiation of vascular plant shoot forms.
While the molecular basis for cytokinin action is quite well understood in flowering plants, little is known about the cytokinin signal transduction in early diverging land plants. The genome of the bryophyte Physcomitrella patens (Hedw.) B.S. encodes three classical cytokinin receptors, the CHASE domain-containing histidine kinases, CHK1, CHK2, and CHK3. In a complementation assay with protoplasts of receptor-deficient Arabidopsis thaliana as well as in cytokinin binding assays, we found evidence that CHK1 and CHK2 receptors can function in cytokinin perception. Using gene targeting, we generated a collection of CHK knockout mutants comprising single (Δchk1, Δchk2, Δchk3), double (Δchk1,2, Δchk1,3, Δchk2,3), and triple (Δchk1,2,3) mutants. Mutants were characterized for their cytokinin response and differentiation capacities. While the wild type did not grow on high doses of cytokinin (1 µM benzyladenine), the Δchk1,2,3 mutant exhibited normal protonema growth. Bud induction assays showed that all three cytokinin receptors contribute to the triggering of budding, albeit to different extents. Furthermore, while the triple mutant showed no response in this bioassay, the remaining mutants displayed budding responses in a diverse manner to different types and concentrations of cytokinins. Determination of cytokinin levels in mutants showed no drastic changes for any of the cytokinins; thus, in contrast to Arabidopsis, revealing only small impacts of cytokinin signaling on homeostasis. In summary, our study provides a first insight into the molecular action of cytokinin in an early diverging land plant and demonstrates that CHK receptors play an essential role in bud induction and gametophore development.
- MeSH
- biotest MeSH
- butadieny farmakologie MeSH
- cytokininy farmakologie MeSH
- fenotyp MeSH
- fyziologická adaptace MeSH
- genový knockout MeSH
- hemiterpeny farmakologie MeSH
- mechy účinky léků genetika metabolismus MeSH
- mutace genetika MeSH
- pentany farmakologie MeSH
- receptory buněčného povrchu chemie metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné proteiny chemie metabolismus MeSH
- terciární struktura proteinů MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem 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.
It has been suggested that a heterogeneous environment enhances species richness and allows for the coexistence of species. However, there is increasing evidence that environmental heterogeneity can have no effect or even a negative effect on plant species richness and plant coexistence at a local scale. We examined whether plant species richness increases with local heterogeneity in the water table depth, microtopography, pH and light availability in a swamp forest community at three local spatial scales (grain: 0.6, 1.2 and 11.4 m). We also used the variance partitioning approach to assess the relative contributions of niche-based and other spatial processes to species occurrence. We found that heterogeneity in microtopography and light availability positively correlated with species richness, in accordance with the habitat heterogeneity hypothesis. However, we recorded different heterogeneity-diversity relationships for particular functional species groups. An increase in the richness of bryophytes and woody plant species was generally related to habitat heterogeneity at all measured spatial scales, whereas a low impact on herbaceous species richness was recorded only at the 11.4 m scale. The distribution of herbaceous plants was primarily explained by other spatial processes, such as dispersal, in contrast to the occurrence of bryophytes, which was better explained by environmental factors. Our results suggest that both niche-based and other spatial processes are important determinants of the plant composition and species turnover at local spatial scales in swamp forests.
