Tropical forests are biodiversity hotspots, but it is not well understood how this diversity is structured and maintained. One hypothesis rests on the generation of a range of metabolic niches, with varied composition, supporting a high species diversity. Characterizing soil metabolomes can reveal fine-scale differences in composition and potentially help explain variation across these habitats. In particular, little is known about canopy soils, which are unique habitats that are likely to be sources of additional biodiversity and biogeochemical cycling in tropical forests. We studied the effects of diverse tree species and epiphytes on soil metabolomic profiles of forest floor and canopy suspended soils in a French Guianese rainforest. We found that the metabolomic profiles of canopy suspended soils were distinct from those of forest floor soils, differing between epiphyte-associated and non-epiphyte suspended soils, and the metabolomic profiles of suspended soils varied with host tree species, regardless of association with epiphyte. Thus, tree species is a key driver of rainforest suspended soil metabolomics. We found greater abundance of metabolites in suspended soils, particularly in groups associated with plants, such as phenolic compounds, and with metabolic pathways related to amino acids, nucleotides, and energy metabolism, due to the greater relative proportion of tree and epiphyte organic material derived from litter and root exudates, indicating a strong legacy of parent biological material. Our study provides evidence for the role of tree and epiphyte species in canopy soil metabolomic composition and in maintaining the high levels of soil metabolome diversity in this tropical rainforest. It is likely that a wide array of canopy microsite-level environmental conditions, which reflect interactions between trees and epiphytes, increase the microscale diversity in suspended soil metabolomes.
- Publication type
- Journal Article MeSH
Three new alkaloids, bersavine (3), muraricine (4), and berbostrejdine (8), together with seven known isoquinoline alkaloids (1-2, 5-7, 9, and 10) were isolated from an alkaloidal extract of the root bark of Berberis vulgaris. The structures of the isolated compounds were determined by spectroscopic methods, including 1D and 2D NMR techniques, HRMS, and optical rotation, and by comparison of the obtained data with those in the literature. The NMR data of berbamine (5), aromoline (6), and obamegine (7) were completely assigned employing 2D NMR experiments. Alkaloids isolated in sufficient amounts were evaluated for their in vitro acetylcholinesterase, butyrylcholinesterase (BuChE), prolyl oligopeptidase, and glycogen synthase kinase-3β inhibitory activities. Selected compounds were studied for their ability to permeate through the blood-brain barrier. Significant human BuChE ( hBuChE) inhibitory activity was demonstrated by 6 (IC50 = 0.82 ± 0.10 μM). The in vitro data were further supported by computational analysis that showed the accommodation of 6 in the active site of hBuChE.
- MeSH
- Acetylcholinesterase metabolism MeSH
- Alkaloids chemistry isolation & purification therapeutic use MeSH
- Alzheimer Disease drug therapy MeSH
- Berberis chemistry MeSH
- Butyrylcholinesterase metabolism MeSH
- Cholinesterase Inhibitors therapeutic use MeSH
- Blood-Brain Barrier drug effects MeSH
- Isoquinolines chemistry isolation & purification therapeutic use MeSH
- Humans MeSH
- Magnetic Resonance Spectroscopy MeSH
- Plant Exudates analysis MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Nitrogen is required for optimal plant growth, especially in young organs such as secondary axes (axes II) after axillary bud outgrowth. Several studies have shown an increase of nitrogen concentration in xylem sap concomitantly with bud outgrowth, but the relation between nitrogen, sugars and plant hormones in axis II still remains unclear. We investigated in Rosa hybrida the involvement of nitrogen nutrition in axis II elongation in relation with sugars and cytokinins using 15N-labeled nitrate and sugars, amino acids and cytokinin quantifications. Besides, we measured the effect of the exogenous supply of these compounds on axis II elongation using in vitro excised bud culture. We demonstrated that nitrogen in the axis II comes mainly from new root uptake after decapitation. Asparagine, which concentration increases in sap exudates and tissues during axis II elongation, was the sole amino acid able to sustain an efficient elongation in vitro when supplied in combination with sucrose.
Root exudates comprise a large variety of compounds released by plants into the rhizosphere, including low-molecular-weight primary metabolites (particularly saccharides, amino acids and organic acids) and secondary metabolites (phenolics, flavonoids and terpenoids). Changes in exudate composition could have impacts on the plant itself, on other plants, on soil properties (e.g. amount of soil organic matter), and on soil organisms. The effects of drought on the composition of root exudates, however, have been rarely studied. We used an ecometabolomics approach to identify the compounds in the exudates of Quercus ilex (holm oak) under an experimental drought gradient and subsequent recovery. Increasing drought stress strongly affected the composition of the exudate metabolome. Plant exudates under drought consisted mainly of secondary metabolites (71% of total metabolites) associated with plant responses to drought stress, whereas the metabolite composition under recovery shifted towards a dominance of primary metabolites (81% of total metabolites). These results strongly suggested that roots exude the most abundant root metabolites. The exudates were changed irreversibly by the lack of water under extreme drought conditions, and the plants could not recover.
The heterotrophic lifestyle of parasitic plants relies on the development of the haustorium, a specific infectious organ required for attachment to host roots. While haustorium development is initiated upon chemodetection of host-derived molecules in hemiparasitic plants, the induction of haustorium formation remains largely unknown in holoparasitic species such as Phelipanche ramosa. This work demonstrates that the root exudates of the host plant Brassica napus contain allelochemicals displaying haustorium-inducing activity on P. ramosa germinating seeds, which increases the parasite aggressiveness. A de novo assembled transcriptome and microarray approach with P. ramosa during early haustorium formation upon treatment with B. napus root exudates allowed the identification of differentially expressed genes involved in hormone signaling. Bioassays using exogenous cytokinins and the specific cytokinin receptor inhibitor PI-55 showed that cytokinins induced haustorium formation and increased parasite aggressiveness. Root exudates triggered the expression of cytokinin-responsive genes during early haustorium development in germinated seeds, and bio-guided UPLC-ESI(+)-/MS/MS analysis showed that these exudates contain a cytokinin with dihydrozeatin characteristics. These results suggest that cytokinins constitutively exudated from host roots play a major role in haustorium formation and aggressiveness in P. ramosa.
MAIN CONCLUSION: This study showed that Bacillus amyloliquefaciens UCMB5113 colonizing Arabidopsis roots changed root structure and promoted growth implying the usability of this strain as a novel tool to support sustainable crop production. Root architecture plays a crucial role for plants to ensure uptake of water, minerals and nutrients and to provide anchorage in the soil. The root is a dynamic structure with plastic growth and branching depending on the continuous integration of internal and environmental factors. The rhizosphere contains a complex microbiota, where some microbes can colonize plant roots and support growth and stress tolerance. Here, we report that the rhizobacterium Bacillus amyloliquefaciens subsp. plantarum UCMB5113 stimulated the growth of Arabidopsis thaliana Col-0 by increased lateral root outgrowth and elongation and root-hair formation, although primary root elongation was inhibited. In addition, the growth of the above ground tissues was stimulated by UCMB5113. Specific hormone reporter gene lines were tested which suggested a role for at least auxin and cytokinin signaling during rhizobacterial modulation of Arabidopsis root architecture. UCMB5113 produced cytokinins and indole-3-acetic acid, and the formation of the latter was stimulated by root exudates and tryptophan. The plant growth promotion effect by UCMB5113 did not appear to depend on jasmonic acid in contrast to the disease suppression effect in plants. UCMB5113 exudates inhibited primary root growth, while a semi-purified lipopeptide fraction did not and resulted in the overall growth promotion indicating an interplay of many different bacterial compounds that affect the root growth of the host plant. This study illustrates that beneficial microbes interact with plants in root development via classic and novel signals.
- MeSH
- Arabidopsis drug effects growth & development microbiology MeSH
- Bacillus amyloliquefaciens drug effects physiology MeSH
- Brassinosteroids pharmacology MeSH
- Cytokinins pharmacology MeSH
- Gibberellins pharmacology MeSH
- Host-Pathogen Interactions * drug effects MeSH
- Plant Roots anatomy & histology drug effects MeSH
- Indoleacetic Acids pharmacology MeSH
- Lipopeptides pharmacology MeSH
- Plant Growth Regulators pharmacology MeSH
- Seedlings drug effects growth & development MeSH
- Publication type
- Journal Article MeSH
... Arrested caries and remineralisation 68 -- 25 Caries in deciduous teeth 69 -- 25 Hidden caries 70 -- 25 Root ... ... Gingival and periodontal fibres 96 Periapical (dentoalveolar) abscess 129 -- Gingival crevicular fluid (exudate ... ... -- Invasive fungal sinusitis 445 -- Surgical damage to the maxillary antrum 445 Displacement of a root ... ... or tooth into the maxillary antrum 445 -- Oroantral communication 445 -- Aspiration of a tooth, root ...
Ninth edition xiii, 545 stran : ilustrace ; 28 cm
- MeSH
- Pathology, Oral MeSH
- Oral Medicine MeSH
- Publication type
- Monograph MeSH
- Conspectus
- Stomatologie
- NML Fields
- zubní lékařství
Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the "secondary compound hypothesis" and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.
- MeSH
- Bacteria classification isolation & purification metabolism MeSH
- Biodegradation, Environmental * MeSH
- Soil Pollutants chemistry toxicity MeSH
- Polychlorinated Biphenyls toxicity MeSH
- Soil Microbiology * MeSH
- Plants metabolism microbiology MeSH
- Secondary Metabolism MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Various low-molecular-weight organic acids (LMWOAs) play an important role in the mobilisation of contaminants and their subsequent uptake by plants. Nano-maghemite (NM) and an amorphous Mn oxide (AMO) were investigated for their stabilisation potential under simulated rhizosphere conditions in terms of their use during chemical stabilisation and aided phytostabilisation of metal(loid)s in contaminated soils. In order to understand the reactivity of these potential sorbents of contaminants in soils and subsequent mobility of metal(loid)s, a set of time-dependent batch leaching experiments was performed using a mix of acetic, lactic, citric, malic and formic acids simulating root exudates. Despite being relatively unstable under given conditions, the AMO proved to be an efficient amendment for rapid stabilisation of both metals and As compared to NM. Generally, low pH (∼ 4) and the presence of citrate complexes resulted in higher mobility of metals in the non- and NM-amended soil. In contrast, the presence of AMO in the soil accelerated the neutralisation reactions related to pH increase and (co-) precipitation of secondary Fe/Mn/Al oxyhydroxides. Mineralogical transformations of the AMO showed to be crucial for contaminant immobilisation.
- MeSH
- Arsenic chemistry MeSH
- Metal Nanoparticles chemistry MeSH
- Metals chemistry MeSH
- Carboxylic Acids chemistry MeSH
- Soil Pollutants chemistry MeSH
- Molecular Weight MeSH
- Oxides chemistry MeSH
- Manganese Compounds chemistry MeSH
- Ferric Compounds chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND AND AIMS: Allelopathy may drive invasions of some exotic plants, although empirical evidence for this theory remains largely inconclusive. This could be related to the large intraspecific variability of chemically mediated plant-plant interactions, which is poorly studied. This study addressed intraspecific variability in allelopathy of Heracleum mantegazzianum (giant hogweed), an invasive species with a considerable negative impact on native communities and ecosystems. METHODS: Bioassays were carried out to test the alleopathic effects of H. mantegazzianum root exudates on germination of Arabidopsis thaliana and Plantago lanceolata. Populations of H. mantegazzianum from the Czech Republic were sampled and variation in the phytotoxic effects of the exudates was partitioned between areas, populations within areas, and maternal lines. The composition of the root exudates was determined by metabolic profiling using ultra-high-performance liquid chromatography with time-of-flight mass spectrometry, and the relationships between the metabolic profiles and the effects observed in the bioassays were tested using orthogonal partial least-squares analysis. KEY RESULTS: Variance partitioning indicated that the highest variance in phytotoxic effects was within populations. The inhibition of germination observed in the bioassay for the co-occurring native species P. lanceolata could be predicted by the metabolic profiles of the root exudates of particular maternal lines. Fifteen compounds associated with this inhibition were tentatively identified. CONCLUSIONS: The results present strong evidence that intraspecific variability needs to be considered in research on allelopathy, and suggest that metabolic profiling provides an efficient tool for studying chemically mediated plant-plant interactions whenever unknown metabolites are involved.
- MeSH
- Allelopathy * MeSH
- Arabidopsis drug effects MeSH
- Heracleum chemistry genetics metabolism MeSH
- Species Specificity MeSH
- Ecosystem MeSH
- Germination drug effects MeSH
- Plant Roots chemistry genetics metabolism MeSH
- Metabolome * MeSH
- Plantago drug effects MeSH
- Plant Exudates chemistry isolation & purification metabolism MeSH
- Introduced Species MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
