ResearchPad - bryology https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Flavonoids and antioxidant activity of rare and endangered fern: <i>Isoetes sinensis</i>]]> https://www.researchpad.co/article/elastic_article_7844 Isoetes sinensis Palmer is a critically endangered, first-class protected plant in China. Until now, researchers have primarily focused on the ultrastructure, phylogeny, and transcriptomes of the plant. However, flavonoid profiles and bioactivity of I. sinensis have not been extensively investigated. To develop the endangered I. sinensis for edible and medicinal purposes, flavonoid content, chemical constitution, and antioxidant activities were investigated in this study. Results revealed the following. 1) The total flavonoid content was determined as 10.74 ± 0.25 mg/g., 2) Antioxidant activities were stronger than most ferns, especially ABTS free radical scavenging activities. 3) Four flavones, containing apigenin, apigenin-7-glucuronide, acacetin-7-O-glcopyranoside, and homoplantageninisoetin; four flavonols, namely, isoetin, kaempferol-3-O-glucoside, quercetin-3-O-[6”-O-(3-hydroxy-3-methylglutaryl)-β-D-glucopyranoside], and limocitrin-Neo; one prodelphinidin (procyanidins;) and one nothofagin (dihydrochalcone) were tentatively identified in the mass spectrometry-DAD (254nm) chromatograms. This study was the first to report on flavonoid content and antioxidant activities of I. sinensis. Stronger antioxidant activity and flavonoid content suggests that the endangered I. sinensis is an important and potentially edible and medicinal plant.

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<![CDATA[The long journey of Orthotrichum shevockii (Orthotrichaceae, Bryopsida): From California to Macaronesia]]> https://www.researchpad.co/article/5c6dca01d5eed0c48452a691

Biogeography, systematics and taxonomy are complementary scientific disciplines. To understand a species’ origin, migration routes, distribution and evolutionary history, it is first necessary to establish its taxonomic boundaries. Here, we use an integrative approach that takes advantage of complementary disciplines to resolve an intriguing scientific question. Populations of an unknown moss found in the Canary Islands (Tenerife Island) resembled two different Californian endemic species: Orthotrichum shevockii and O. kellmanii. To determine whether this moss belongs to either of these species and, if so, to explain its presence on this distant oceanic island, we combined the evaluation of morphological qualitative characters, statistical morphometric analyses of quantitative traits, and molecular phylogenetic inferences. Our results suggest that the two Californian mosses are conspecific, and that the Canarian populations belong to this putative species, with only one taxon thus involved. Orthotrichum shevockii (the priority name) is therefore recognized as a morphologically variable species that exhibits a transcontinental disjunction between western North America and the Canary Islands. Within its distribution range, the area of occupancy is limited, a notable feature among bryophytes at the intraspecific level. To explain this disjunction, divergence time and ancestral area estimation analyses are carried out and further support the hypothesis of a long-distance dispersal event from California to Tenerife Island.

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<![CDATA[Performance of Forest Bryophytes with Different Geographical Distributions Transplanted across a Topographically Heterogeneous Landscape]]> https://www.researchpad.co/article/5989da40ab0ee8fa60b89aa9

Most species distribution models assume a close link between climatic conditions and species distributions. Yet, we know little about the link between species' geographical distributions and the sensitivity of performance to local environmental factors. We studied the performance of three bryophyte species transplanted at south- and north-facing slopes in a boreal forest landscape in Sweden. At the same sites, we measured both air and ground temperature. We hypothesized that the two southerly distributed species Eurhynchium angustirete and Herzogiella seligeri perform better on south-facing slopes and in warm conditions, and that the northerly distributed species Barbilophozia lycopodioides perform better on north-facing slopes and in relatively cool conditions. The northern, but not the two southern species, showed the predicted relationship with slope aspect. However, the performance of one of the two southern species was still enhanced by warm temperatures. An important reason for the inconsistent results can be that microclimatic gradients across landscapes are complex and influenced by many climate-forcing factors. Therefore, comparing only north- and south-facing slopes might not capture the complexity of microclimatic gradients. Population growth rates and potential distributions are the integrated results of all vital rates. Still, the study of selected vital rates constitutes an important first step to understand the relationship between population growth rates and geographical distributions and is essential to better predict how climate change influences species distributions.

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<![CDATA[Total flavonoid concentrations of bryophytes from Tianmu Mountain, Zhejiang Province (China): Phylogeny and ecological factors]]> https://www.researchpad.co/article/5989db50ab0ee8fa60bdbd9e

The flavonoids in bryophytes may have great significance in phylogeny and metabolism research. However, to date there has been little research on bryophyte metabolites, especially flavonoids. To redress this somewhat, we determined flavonoid concentrations of bryophytes from Tianmu Mountain through a colorimetric assay and considered the factors influencing the results. This is the first time that the flavonoid contents of bryophytes have been examined in detail. The results revealed a range of total flavonoid concentrations in 90 samples collected from Tianmu Mountain from 1.8 to 22.3 mg/g (w/w). The total flavonoid contents of liverworts were generally higher than those of mosses; acrocarpous mosses had generally higher values than that of pleurocarpous mosses. The total flavonoid contents of bryophytes growing at lower light levels were general higher than those growing in full-sun. The total flavonoid contents of epiphytic bryophytes were highest, while those of aquatic bryophytes were the lowest. Total flavonoid contents of species growing at low-latitudes were much higher than those at high-latitude individuals. In conclusion, total flavonoid contents of bryophytes have some connection with plant phylogeny; more flavonoids might be contained in relatively primitive bryophytes. Meanwhile, the effects of ecological factors on total flavonoid contents of bryophytes exist; light and habitat (especially tree habitat and river habitat) might be representative factor.

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<![CDATA[Chronic Nitrogen Deposition Has a Minor Effect on the Quantity and Quality of Aboveground Litter in a Boreal Forest]]> https://www.researchpad.co/article/5989dad2ab0ee8fa60bb6821

There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal soils. However, key underlying mechanisms explaining this increase have not been resolved. Two potentially important mechanisms are that aboveground litter production increases, or that litter quality changes in response to N enrichment. As such, our aim was to quantify whether simulated chronic N deposition caused changes in aboveground litter production or quality in a boreal forest. We conducted a long-term (17 years) stand-scale (0.1 ha) forest experiment, consisting of three N addition levels (0, 12.5, and 50 kg N ha-1 yr-1) in northern Sweden, where background N deposition rates are very low. We measured the annual quantity of litter produced for 8 different litter categories, as well as their concentrations of C, N, phosphorus (P), lignin, cellulose and hemi-cellulose. Our results indicate that mosses were the only major litter component showing significant quantitative and qualitative alterations in response to the N additions, indicative of their ability to intercept a substantial portion of the N added. These effects were, however, offset by the other litter fractions where we found no changes in the total litter fluxes, or individual chemical constituents when all litter categories were summed. This study indicates that the current annual litter fluxes cannot explain the increase in soil C that has occurred in our study system in response to simulated chronic N application. These results suggest that other mechanisms are likely to explain the increased soil C accumulation rate we have observed, such as changes in soil microbial activity, or potentially transient changes in aboveground litter inputs that were no longer present at the time of our study.

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<![CDATA[Impact of Land-Use Intensity and Productivity on Bryophyte Diversity in Agricultural Grasslands]]> https://www.researchpad.co/article/5989db03ab0ee8fa60bc78bf

While bryophytes greatly contribute to plant diversity of semi-natural grasslands, little is known about the relationships between land-use intensity, productivity, and bryophyte diversity in these habitats. We recorded vascular plant and bryophyte vegetation in 85 agricultural used grasslands in two regions in northern and central Germany and gathered information on land-use intensity. To assess grassland productivity, we harvested aboveground vascular plant biomass and analyzed nutrient concentrations of N, P, K, Ca and Mg. Further we calculated mean Ellenberg indicator values of vascular plant vegetation. We tested for effects of land-use intensity and productivity on total bryophyte species richness and on the species richness of acrocarpous (small & erect) and pleurocarpous (creeping, including liverworts) growth forms separately. Bryophyte species were found in almost all studied grasslands, but species richness differed considerably between study regions in northern Germany (2.8 species per 16 m2) and central Germany (6.4 species per 16 m2) due environmental differences as well as land-use history. Increased fertilizer application, coinciding with high mowing frequency, reduced bryophyte species richness significantly. Accordingly, productivity estimates such as plant biomass and nitrogen concentration were strongly negatively related to bryophyte species richness, although productivity decreased only pleurocarpous species. Ellenberg indicator values for nutrients proved to be useful indicators of species richness and productivity. In conclusion, bryophyte composition was strongly dependent on productivity, with smaller bryophytes that were likely negatively affected by greater competition for light. Intensive land-use, however, can also indirectly decrease bryophyte species richness by promoting grassland productivity. Thus, increasing productivity is likely to cause a loss of bryophyte species and a decrease in species diversity.

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<![CDATA[Forests Regenerating after Clear-Cutting Function as Habitat for Bryophyte and Lichen Species of Conservation Concern]]> https://www.researchpad.co/article/5989dae1ab0ee8fa60bbbf1b

The majority of managed forests in Fennoscandia are younger than 70 years old but yet little is known about their potential to host rare and threatened species. In this study, we examined red-listed bryophytes and lichens in 19 young stands originating from clear-cutting (30–70 years old) in the boreal region, finding 19 red-listed species (six bryophytes and 13 lichens). We used adjoining old stands, which most likely never had been clear-cut, as reference. The old stands contained significantly more species, but when taking the amount of biological legacies (i.e., remaining deciduous trees and dead wood) from the previous forest generation into account, bryophyte species number did not differ between old and young stands, and lichen number was even higher in young stands. No dispersal effect could be detected from the old to the young stands. The amount of wetlands in the surroundings was important for bryophytes, as was the area of old forest for both lichens and bryophytes. A cardinal position of young stands to the north of old stands was beneficial to red-listed bryophytes as well as lichens. We conclude that young forest plantations may function as habitat for red-listed species, but that this depends on presence of structures from the previous forest generation, and also on qualities in the surrounding landscape. Nevertheless, at repeated clear-cuttings, a successive decrease in species populations in young production stands is likely, due to increased fragmentation and reduced substrate amounts. Retention of dead wood and deciduous trees might be efficient conservation measures. Although priority needs to be given to preservation of remnant old-growth forests, we argue that young forests rich in biological legacies and located in landscapes with high amounts of old forests may have a conservation value.

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<![CDATA[Transcriptome of Protoplasts Reprogrammed into Stem Cells in Physcomitrella patens]]> https://www.researchpad.co/article/5989da9cab0ee8fa60ba4019

Background

Differentiated plant cells can retain the capacity to be reprogrammed into pluripotent stem cells during regeneration. This capacity is associated with both cell cycle reactivation and acquisition of specific cellular characters. However, the molecular mechanisms underlying the reprogramming of protoplasts into stem cells remain largely unknown. Protoplasts of the moss Physcomitrella patens easily regenerate into protonema and therefore provide an ideal system to explore how differentiated cells can be reprogrammed to produce stem cells.

Principal findings

We obtained genome-wide digital gene expression tag profiles within the first three days of P. patens protoplast reprogramming. At four time-points during protoplast reprogramming, the transcript levels of 4827 genes changed more than four-fold and their expression correlated with the reprogramming phase. Gene ontology (GO) and pathway enrichment analysis of differentially expressed genes (DEGs) identified a set of significantly enriched GO terms and pathways, most of which were associated with photosynthesis, protein synthesis and stress responses. DEGs were grouped into six clusters that showed specific expression patterns using a K-means clustering algorithm. An investigation of function and expression patterns of genes identified a number of key candidate genes and pathways in early stages of protoplast reprogramming, which provided important clues to reveal the molecular mechanisms responsible for protoplast reprogramming.

Conclusions

We identified genes that show highly dynamic changes in expression during protoplast reprogramming into stem cells in P. patens. These genes are potential targets for further functional characterization and should be valuable for exploration of the mechanisms of stem cell reprogramming. In particular, our data provides evidence that protoplasts of P. patens are an ideal model system for elucidation of the molecular mechanisms underlying differentiated plant cell reprogramming.

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<![CDATA[Molecular Species Delimitation in the Racomitrium canescens Complex (Grimmiaceae) and Implications for DNA Barcoding of Species Complexes in Mosses]]> https://www.researchpad.co/article/5989dab2ab0ee8fa60babbb5

In bryophytes a morphological species concept is still most commonly employed, but delimitation of closely related species based on morphological characters is often difficult. Here we test morphological species circumscriptions in a species complex of the moss genus Racomitrium, the R. canescens complex, based on variable DNA sequence markers from the plastid (rps4-trnT-trnL region) and nuclear (nrITS) genomes. The extensive morphological variability within the complex has led to different opinions about the number of species and intraspecific taxa to be distinguished. Molecular phylogenetic reconstructions allowed to clearly distinguish all eight currently recognised species of the complex plus a ninth species that was inferred to belong to the complex in earlier molecular analyses. The taxonomic significance of intraspecific sequence variation is discussed. The present molecular data do not support the division of the R. canescens complex into two groups of species (subsections or sections). Most morphological characters, albeit being in part difficult to apply, are reliable for species identification in the R. canescens complex. However, misidentification of collections that were morphologically intermediate between species questioned the suitability of leaf shape as diagnostic character. Four partitions of the molecular markers (rps4-trnT, trnT-trnL, ITS1, ITS2) that could potentially be used for molecular species identification (DNA barcoding) performed almost equally well concerning amplification and sequencing success. Of these, ITS1 provided the highest species discrimination capacity and should be considered as a DNA barcoding marker for mosses, especially in complexes of closely related species. Molecular species identification should be complemented by redefining morphological characters, to develop a set of easy-to-use molecular and non-molecular identification tools for improving biodiversity assessments and ecological research including mosses.

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<![CDATA[Crown Group Lejeuneaceae and Pleurocarpous Mosses in Early Eocene (Ypresian) Indian Amber]]> https://www.researchpad.co/article/5989da28ab0ee8fa60b81861

Cambay amber originates from the warmest period of the Eocene, which is also well known for the appearance of early angiosperm-dominated megathermal forests. The humid climate of these forests may have triggered the evolution of epiphytic lineages of bryophytes; however, early Eocene fossils of bryophytes are rare. Here, we present evidence for lejeuneoid liverworts and pleurocarpous mosses in Cambay amber. The preserved morphology of the moss fossil is inconclusive for a detailed taxonomic treatment. The liverwort fossil is, however, distinctive; its zig-zagged stems, suberect complicate-bilobed leaves, large leaf lobules, and small, deeply bifid underleaves suggest a member of Lejeuneaceae subtribe Lejeuneinae (Harpalejeunea, Lejeunea, Microlejeunea). We tested alternative classification possibilities by conducting divergence time estimates based on DNA sequence variation of Lejeuneinae using the age of the fossil for corresponding age constraints. Consideration of the fossil as a stem group member of Microlejeunea or Lejeunea resulted in an Eocene to Late Cretaceous age of the Lejeuneinae crown group. This reconstruction is in good accordance with published divergence time estimates generated without the newly presented fossil evidence. Balancing available evidence, we describe the liverwort fossil as the extinct species Microlejeunea nyiahae, representing the oldest crown group fossil of Lejeuneaceae.

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<![CDATA[Conserved Organisation of 45S rDNA Sites and rDNA Gene Copy Number among Major Clades of Early Land Plants]]> https://www.researchpad.co/article/5989db05ab0ee8fa60bc7f2b

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.

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<![CDATA[Physiological Responses of Two Epiphytic Bryophytes to Nitrogen, Phosphorus and Sulfur Addition in a Subtropical Montane Cloud Forest]]> https://www.researchpad.co/article/5989da2eab0ee8fa60b83687

Atmospheric depositions pose significant threats to biodiversity and ecosystem function. However, the underlying physiological mechanisms are not well understood, and few studies have considered the combined effects and interactions of multiple pollutants. This in situ study explored the physiological responses of two epiphytic bryophytes to combined addition of nitrogen, phosphorus and sulfur. We investigated the electrical conductivity (EC), total chlorophyll concentration (Chl), nutrient stoichiometry and chlorophyll fluorescence signals in a subtropical montane cloud forest in south-west China. The results showed that enhanced fertilizer additions imposed detrimental effects on bryophytes, and the combined enrichment of simulated fertilization exerted limited synergistic effects in their natural environments. On the whole, EC, Chl, the effective quantum yield of photosystem II (ΦPSII) and photochemical quenching (qP) were the more reliable indicators of increased artificial fertilization. However, conclusions on nutrient stoichiometry should be drawn cautiously concerning the saturation uptake and nutrient interactions in bryophytes. Finally, we discuss the limitations of prevailing fertilization experiments and emphasize the importance of long-term data available for future investigations.

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