RESUMO
Twelve dihydrostilbenes (including five new analogues) were prepared by the Witting-Hornor reaction from appropriate aromatic aldehydes and phosphonate esters, followed by hydrogenation in five steps. The in vitro inhibition activity against human neutrophil elastase (HNE) of these dihydrostilbenes was evaluated, and three 1,2-dihydroxylated dihydrostilbenes (6b, 6j, and 6l) exhibited stronger inhibitory activity against HNE than other analogues.
Assuntos
Di-Hidroestilbenoides , Elastase de Leucócito , Humanos , Estrutura MolecularRESUMO
Salix species are widely used as vegetation filters because of their flourishing root system and fast growth rate. However, studies have yet to determine whether the root system functions in vegetable filters with mixed heavy metal (HM) pollution or whether initial cutting participates in the phytoextraction of HMs. This study aims to determine the function of the root system and initial cutting as vegetation filters in the absorption and accumulation of Cd and Cu. Thick (>1 cm in diameter) and fine (<1 cm in diameter) initial cuttings of Salix matsudana were planted in a nutrient solution with single and mixed (Cd + Cu) treatments. The roots of several initial cuttings were removed daily to eradicate rhizofiltration. Results revealed that the existence of the root system altered distribution and interaction of Cd and Cu in plant organs and enhanced tolerance and phytoextraction capacity of plants. The initial cuttings could also absorb and accumulate HMs in the early growth stages of willow without roots. Cu inhibited the plant absorption and accumulation of Cd and promoted Cd transport to shoots. Cd inhibited the Cu absorption of the root system. Our study provided essential data regarding woody species as vegetation filters of HM pollution.
Assuntos
Salix , Poluentes do Solo/análise , Biodegradação Ambiental , Cádmio/análise , Raízes de PlantasRESUMO
Flowering plants interact simultaneously with mutualistic pollinators and antagonistic herbivores such that plant-mediated interactions between pollinators and herbivores must exist. Although the effects of herbivores on pollinator behavior have been investigated extensively, the effect of pollinators on herbivore performance has seldom been explored. We hypothesized that insect pollinators could improve the survival and growth of pre-dispersal seed predators by increasing seed production. We tested this hypothesis along three transects radiating from well-established apiaries in an alpine meadow by supplementing pollination in sites close to and distant from apiaries and subsequently examining seed production of the dominant nectariferous plant species Saussurea nigrescens (Asteraceae) and the performance of three dominant pre-dispersal seed predators (tephritid fly species). Pollen supplementation (1) significantly increased seed set and mass of developed seed per capitulum (i.e., flowerhead) in the distant but not the close sites, (2) did not change the survival and growth rates of the smaller-bodied species (Tephritis femoralis and Campiglossa nigricauda) at either site, but (3) improved the performance of the larger-bodied seed predator (Terellia megalopyge) at distant sites but not close sites. In addition, the larger-bodied tephritid fly showed higher infestation rates and relative abundance in the close sites than in the distant sites, whereas the smaller-bodied species had lower relative abundances in the close sites and similar infestation rates in both site types. These observations demonstrate contrasting effects of plant mutualists on the performance of antagonists with potential consequences for population sizes of insect herbivores.
Assuntos
Pradaria , Polinização , Animais , Abelhas , Herbivoria , Insetos , SementesRESUMO
Plants have evolved intricate immune mechanisms to combat pathogen infection. Upon perception of pathogen-derived signals, plants accumulate defense hormones such as ethylene (ET), jasmonate, salicylate, and damage-associated molecular patterns to amplify immune responses. In particular, the Arabidopsis peptide Pep1 and its family members are thought to be damage-associated molecular patterns that trigger immunity through Pep1 receptor kinases PEPR1 and PEPR2. Here we show that PEPR1 specifically interacts with receptor-like cytoplasmic kinases botrytis-induced kinase 1 (BIK1) and PBS1-like 1 (PBL1) to mediate Pep1-induced defenses. In vitro and in vivo studies suggested that PEPR1, and likely PEPR2, directly phosphorylates BIK1 in response to Pep1 treatment. Surprisingly, the pepr1/pepr2 double-mutant seedlings displayed reduced in sensitivity to ET, as indicated by the elongated hypocotyls. ET-induced expression of defense genes and resistance to Botrytis cinerea were compromised in pepr1/pepr2 and bik1 mutants, reenforcing an important role of PEPRs and BIK1 in ET-mediated defense signaling. Pep treatment partially mimicked ET-induced seedling growth inhibition in a PEPR- and BIK1-dependent manner. Furthermore, both ET and Pep1 treatments induced BIK1 phosphorylation in a PEPR-dependent manner. However, the Pep1-induced BIK1 phosphorylation, seedling growth inhibition, and defense gene expression were independent of canonical ET signaling components. Together our results illustrate a mechanism by which ET and PEPR signaling pathways act in concert to amplify immune responses.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Etilenos/farmacologia , Imunidade Vegetal , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Superfície Celular/metabolismo , DNA Complementar/metabolismo , Resistência à Doença , Genes Reporter , Mutação , Fosforilação , Reguladores de Crescimento de Plantas/farmacologia , Domínios e Motivos de Interação entre Proteínas , Explosão Respiratória , Transdução de Sinais , Técnicas do Sistema de Duplo-HíbridoRESUMO
This study aimed to compare growth performance and heavy metal (HM) accumulation at different cutting positions of Salix species grown in multi-metal culture. Three Salix species stems cut at different positions (apical to basal) were grown hydroponically for four weeks. The plants were then treated for three weeks with 0, 5, 10, and 20 µM Cd, Cu, Pb, and Zn, resulting in total metal concentrations of 0, 20, 40, and 80 µM. The growth parameters and HM content in shoots and initial cutting were measured. Results showed that, compared with S. fragilis, S. matsudana grew more poorly in uncontaminated condition but grew better and accumulated lower metal in shoots under mixed HM treatment. In addition, cuttings from apical parent stem position exhibited poorer growth performance before and after treatment, as well as greater metal content in shoots than base parts under the HM treatment. These results suggest that S. matsudana may undergo a special mechanism to hinder metals in the initial cutting, thus mitigating growth damage. The apical portion also showed poor resistance against the invasion of mixed HMs because of the immature structure. Therefore, in the selection of phytoremediation plants, metal accumulation ability is not proportional to growth performance.
Assuntos
Metais Pesados/farmacologia , Salix/efeitos dos fármacos , Poluentes do Solo/farmacologia , Biodegradação Ambiental , Metais Pesados/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Salix/crescimento & desenvolvimento , Salix/metabolismo , Poluentes do Solo/metabolismo , Especificidade da EspécieRESUMO
A bacterium isolated from Lake Taihu was identified as Pseudomonas sp. A3CT, which performed different effects on Microcystis spp. Growth of Microcystis flos-aquae and Microcystis aeruginosa was assessed in co-culture with A3CT to determine the stimulatory or inhibitory effects on these toxic, bloom-forming Microcystis strains. Results demonstrated that the impacts of A3CT were species specific. A3CT promoted the growth of M. aeruginosa but inhibited growth of M. flos-aquae. To investigate the cause of this phenomenon, the chemical composition of A3CT exudates and the impact of exposure to A3CT exudates on the two Microcystis species were determined. Results suggested that the observed differential growth responses of the two microalgae to A3CT exposure might be related to two components in A3CT exudates NH4 (+) and cadaverine. Growth stimulation of M. aeruginosa by A3CT was significantly related to NH4 (+) concentration. Cadaverine possibly acted as a growth inhibitor of M. flos-aquae. The different effects of cadaverine on growth of the two Microcystis strains suggested that A3CT might play a role in intrageneric succession patterns observed during Microcystis blooms in Lake Taihu.
Assuntos
Cadaverina/farmacologia , Microcystis/crescimento & desenvolvimento , Pseudomonas/química , Cadaverina/isolamento & purificação , Cadaverina/metabolismo , Eutrofização , Água Doce/microbiologia , Lagos , Interações Microbianas , Microcystis/efeitos dos fármacos , Pseudomonas/fisiologia , Especificidade da EspécieRESUMO
To understand the further impacts of multiple stressors in freshwater, we investigated the effects of heavy metal (HM, Cu and Zn) and nutrient enrichments (nitrogen and phosphorus, NP) on microbial decomposition of Pterocarya stenoptera litter and the associated extracellular enzyme activities and microbial biomass with microcosms. Results showed that the decomposition rates were slower in the polluted stream waters than those in the unpolluted ones, which corresponded to lower microbial biomass and integrated enzyme activities of cellulose and ß-glucosidase. The decomposition rates were accelerated at low HM level, which was associated with the stimulated enzyme activities of hydrolytic enzymes or was stimulated by both NP levels in polluted stream waters. In particular, the hydrolase enzyme activities of microbial communities in polluted stream waters were stimulated by low HM level, suggesting that low HM level-stimulated litter decomposition may be due to the increased enzymatic activities. When microbial communities were exposed to HM and NP simultaneously, the inhibitory effect (in unpolluted stream waters) or the stimulated effect (in polluted stream waters) of low HM concentration was enhanced and attenuated, respectively, which suggests that the NP antagonistic effect against HM toxicity on litter decomposition may contribute to the litter-associated extracellular enzyme activities. These results suggest that the co-occurrence of HM and NP may have antagonistic effects on stream ecosystem functioning.
Assuntos
Adaptação Fisiológica/fisiologia , Bactérias/efeitos dos fármacos , Folhas de Planta/química , Plantas/química , Poluentes Químicos da Água/farmacologia , Biodegradação Ambiental , Cobre/química , Cobre/farmacologia , Nitrogênio/química , Nitrogênio/farmacologia , Fósforo/química , Fósforo/farmacologia , Rios , Fatores de Tempo , Poluentes Químicos da Água/química , Zinco/química , Zinco/farmacologiaRESUMO
Biomass conversion aims at degrading the structural polysaccharides of lignocellulose into reducing sugars. Pretreatment is necessary to overcome the recalcitrance of lignocellulose. The DES La/ChCl in this paper was selected based on our previous study. To examine cellulase adsorption of lignocellulose after DES pretreatment, sorghum straw was pretreated with DES under different condition. The adsorption improvement of cellulase on lignocellulose after DES pretreatment has positive impact on reducing sugar production of biomass. After DES pretreatment, 1. pore corrosion caused the upward trend of pore radius and the downward trend of SSA. 2. the hydrogen bounding force of pretreated sorghum straw and MCC decreased, the hydrogen bounding force of pretreated lignin increased. 3. although the unsaturation of pretreated lignin increased, DES pretreatment is helpful for the removal of lignin. 4. The decrease in the hydrophobicity of sorghum straw make it easier to disperse. 5. the Zeta potential of pretreated sorghum straw shifted towards the positively charged region, while pretreated lignin shifted towards the negatively charged region. 6. different adsorption behaviors were observed in specific components of cellulase mixtures (BGs, CBHs, EGs and xlylanase). These results revealing the mechanism of enzyme adsorption are conductive for understanding the role of pretreatment in biomass conversion.
Assuntos
Celulase , Sorghum , Lignina/química , Celulase/química , Adsorção , Polissacarídeos/química , Hidrogênio , Digestão , HidróliseRESUMO
Plant litter decomposition is a natural pathway of heavy metal cycling in soil ecosystems, but the dynamics of heavy metal release during litter decomposition are relatively poorly understood. The purpose of this study was to investigate the effects of species, soil fauna and soil Cd addition on litter decomposition and Cd release dynamics. Therefore, we selected two plants, Solanum nigrum and S. lycopersicum with large differences in Cd accumulation capacity. First, they were enriched with Cd during the growing period and leaf litter was harvested after 6 months of pretreatment. Then, the decomposition of leaf litter was conducted with or without soil Cd and Eisenia fetida through lab pot tests. Our results showed that leaf litter Cd led to a significant decrease in litter decomposition rate (K value), with a maximum decrease of 32.1% in S. nigrum and 30.1% in S. lycopersicum. We observed that the presence of E. fetida significantly increased K value, but the effect was similar in the +leaf Cd treatment and the -leaf Cd treatment, both for S. nigrum and S. lycopersicum. Interestingly, the litter Cd concentration did not decrease during decomposition, but showed an increasing trend, especially for S. nigrum in the +soil Cd treatment. Moreover, the litter Cd remains was higher in the +soil Cd treatment compared to the -soil Cd treatment for both S. nigrum and S. lycopersicum, no matter whether with or without E. fetida. This result suggests that the Cd may be transferred from soil to litter, thus increasing the litter Cd remains. Overall, our study shows that leaf litter Cd slowed down the carbon cycling in ecosystems. In addition, the release of litter Cd has a lag, and the litter has a certain adsorption capacity for soil Cd, which intensifies the harm to the ecology during litter transfer.
Assuntos
Metais Pesados , Poluentes do Solo , Solanum lycopersicum , Solanum nigrum , Cádmio/análise , Solanum nigrum/metabolismo , Biodegradação Ambiental , Solo , Ecossistema , Poluentes do Solo/análise , Metais Pesados/metabolismo , Folhas de Planta/químicaRESUMO
Leaves are essential for plants, enabling photosynthesis and transpiration. In arid regions, water availability limits plant growth. Some plants, like Elaeagnus angustifolia, a sandy sub-tree species widely distributed in arid and semi-arid regions, have unique leaf structures to reduce water loss and solar radiation. Here, we describe the leaves of Elaeagnus angustifolia L., with special functioning trichomes. Through leaf submicroscopic structure observation, in situ water collection experiments, photosynthesis measurements, and reflection spectrum analysis, we investigated E. angustifolia leaves, focusing on their functioning trichomes. These trichomes capture water vapor, reflect UV and NIR light, and possess a 3D interface structure composed of 1D and 2D structures. The 1D conical structure captures water droplets, which are then gathered by the radial conical structure and guided towards the stomata through wedge-shaped grooves on the 2D umbrella structure. The trichomes also reflect sunlight, with micropapillae reflecting UV light and the umbrella structure reflecting NIR light. These mechanisms reduce leaf temperature, respiration, and water transpiration, protecting against solar radiation damage. This study provides insights into water collection and light-reflection mechanisms, revealing adaptive strategies of plants with large leaves in arid regions.
RESUMO
Biodegradable plastic is considered one of the most promising alternatives to agricultural mulch. However, the impact of biodegradable microplastics on agricultural ecosystems is still lacking. We conducted a controlled experiment with polylactic acid microplastics (PLA MPs) to examine the effects of biodegradable plastic on soil properties, corn growth, the microbial community and hotspots of enzyme activity. The results showed that PLA MPs in soil significantly reduced the soil pH value but increased the soil C:N ratio. High levels of PLA MPs significantly reduced the biomass of plant shoots and roots as well as chlorophyll, leaf C and N and root N contents. PLA MPs increased bacterial abundance but decreased the abundance of dominant fungal taxa. As the level of PLA MPs increased, the soil bacterial community structure became more complex, while the fungal community became more singular. The results of the in situ zymogram showed that low levels of PLA MPs increased the hotspots of enzyme activity. The effect of PLA MPs on enzyme activity hotspots was regulated by a combination of soil properties and microbial diversity. Generally, the addition of PLA MPs at high concentrations will have a negative impact on soil characteristics, soil microbials and plant growth in a short period of time. Therefore, we should be aware of the potential risks of biodegradable plastic to agricultural ecosystems.
Assuntos
Plásticos Biodegradáveis , Microbiota , Microplásticos , Plásticos/toxicidade , Poliésteres , Solo , Microbiologia do SoloRESUMO
The ecotoxicological effects of microplastics, a new and widespread ecosystem pollutant, have been extensively reported. However, it remains unclear whether soil fauna transfer microplastics and whether migration behaviours influence subsequent ecological functions in terrestrial ecosystems. We investigated the transfer patterns of microplastics and their adsorbed substances by soil animals (the springtail, Folsomia candida) and the effect of the transfer on the decomposition of soil organic matter through a standardized cotton strip assay. The results showed that springtails had a strong ability to transfer microplastics into the soil. The adsorbed nutrient (nitrogen; N), pollutant (cadmium; Cd), and green fluorescent Escherichia coli (GFP-E. coli) were also transferred with the microplastics. In addition, cotton strip decomposition was accelerated when the microplastics adsorbed N, but the adsorption of Cd decreased decomposition. These ecological effects were particularly strong for small microplastics. Microplastic transfer regulated soil bacterial communities, promoting the growth of Ascomycota fungi and inhibiting that of Basidiomycota, leading to cotton strip decomposition. Thus, microplastic pollution may occur at one site, but microplastics can be transferred anywhere in terrestrial ecosystems by soil animals and adsorb other substances, including nutrients and pollutants, that affect ecosystem function. Therefore, more studies on the migration behaviour of microplastics are necessary.
Assuntos
Microplásticos , Poluentes do Solo , Animais , Solo , Plásticos , Ecossistema , Poluentes do Solo/toxicidade , Cádmio , Escherichia coliRESUMO
Human activities are increasing the input of atmospheric particulate pollutants to forests. The components of particulate pollutants include inorganic anions, base cations and hydrocarbons. Continuous input of particulate pollutants may affect soil functioning in forests, but their effects may be modified by soil fauna. However, studies investigating how soil fauna affects the effects of particulate pollutants on soil functioning are lacking. Here, we investigated how earthworms and the particulate components interact in affecting soil enzymatic functions in a deciduous (Quercus variabilis) and a coniferous (Pinus massoniana) forest in southeast China. We manipulated the addition of nitrogen (N, ammonium nitrate), sodium (Na, sodium chloride) and polycyclic aromatic hydrocarbons (PAHs, five mixed PAHs) in field mesocosms with and without Eisenia fetida, an earthworm species colonizing forests in eastern China. After one year, N and Na addition increased, whereas PAHs decreased soil enzymatic functions, based on average Z scores of extracellular enzyme activities. Earthworms generally stabilized soil enzymatic functions via neutralizing the effects of N, Na and PAHs addition in the deciduous but not in the coniferous forest. Specifically, earthworms neutralized the effects of N and Na addition on soil pH and the effects of the addition of PAHs on soil microbial biomass. Further, both particulate components and earthworms changed the correlations among soil enzymatic and other ecosystem functions in the deciduous forest, but the effects depended on the type of particulate components. Generally, the effects of particulate components and earthworms on soil enzymatic functions were weaker in the coniferous than the deciduous forest. Overall, the results indicate that earthworms stabilize soil enzymatic functions in the deciduous but not the coniferous forest irrespective of the type of particulate components. This suggests that earthworms may neutralize the influence of atmospheric particulate pollutants on ecosystem functions, but the neutralization may be restricted to deciduous forests.
Assuntos
Poluentes Ambientais , Oligoquetos , Hidrocarbonetos Policíclicos Aromáticos , Animais , Humanos , Ecossistema , Florestas , SoloRESUMO
Aquatic litter decomposition is highly dependent on contributions and interactions at different trophic levels. The invasion of alien aquatic organisms like the channeled apple snail (Pomacea canaliculata) might lead to changes in the decomposition process through new species interactions in the invaded wetland. However, it is not clear how aquatic macroinvertebrate predators like the Chinese mitten crab (Eriocheir sinensis) will affect the nutrient cycle in freshwater ecosystems in the face of new benthic invasion. We used the litter bag method to explore the top-down effect of crabs on the freshwater nutrient cycle with the help of soil zymography (a technology previously used in terrestrial ecosystems). The results showed significant feeding effects of crabs and snails on lotus leaf litter and cotton strips. Crabs significantly inhibited the intake of lotus litter and cotton strips and the ability to transform the environment of snails by predation. Crabs promoted the decomposition of various litter substrates by affecting the microbial community structure in the sediment. These results suggest that arthropod predators increase the complexity of detrital food webs through direct and indirect interactions, and consequently have an important impact on the material cycle and stability of freshwater ecosystems. This top-down effect makes macrobenthos play a key role in the biological control and engineering construction of freshwater ecosystems.
RESUMO
Behavior affects an individual's life in all aspects, e.g., enhancing fitness, leveraging predation risk, and reducing competition with conspecifics. However, the sequential distribution of behaviors received less attention and is unclear what the function of displacement behavior is. Displacement activities can be found in vertebrate species but there is no formal method to determine whether a behavior is expressed as a displaced or normal activity. Analyzing the sequential distributions of behaviors in a natural setting may allow researchers to identify unexpected distributions as a possible signature of displacement activities. In this study, we used a behavior random permutation model to detect the presence of a displacement activity in the Tibetan antelope Pantholops hodgsonii and the Tibetan gazelle Procapra picticaudata. The results showed that grooming in both ungulates tended to be accompanied with vigilance, and the frequency of grooming after vigilance was significantly higher than before vigilance. A significant positive correlation between the scan rate and grooming rate in the 2 ungulates was obtained. We suggest that grooming could sometimes be expressed as a displacement activity in ungulates. In addition to providing a general method for further research on displacement activities in a variety of animal species, this study sheds light on the importance of a spectral analysis of sequential distribution of animal behaviors. Behavior random permutation models can be used to explore the relevance between any 2 behaviors in a specific sequence, especially to identify a myriad of unexpected behaviors relative to their normal context of occurrence.
RESUMO
Earthworms modulate carbon and nitrogen cycling in terrestrial ecosystems, but their effect may be compromised by the deposition of pollutants from industrial emissions. However, studies investigating how deposited compounds affect the role of earthworms in carbon cycling such as litter decomposition are lacking, although the interactions of earthworms and deposited compounds are important for understanding the impact of pollutants on ecosystems and the potential of earthworms in bioremediation. We performed a 365-day in situ litterbag decomposition experiment in a deciduous (Quercus variabilis) and coniferous (Pinus massoniana) forest in southeast China. We manipulated nitrogen (N), sodium (Na), and polycyclic aromatic hydrocarbons (PAHs) as model compounds during litter decomposition with and without earthworms (Eisenia fetida). After one year, N, Na, and PAH all slowed down litter mass loss, with the effects of Na being the strongest. By contrast, E. fetida generally increased litter mass loss, and the positive effects were uniformly maintained irrespective of the type of compounds added. However, the pathways to how earthworms increased litter mass loss varied among the compounds added and the two forests studied. As indicated by structural equation modeling, earthworms mitigated the negative effects of deposited compounds by directly increasing litter mass loss and indirectly increasing soil pH and microbial biomass. Overall, the results indicate that the acceleration of litter mass loss by earthworms is little affected by deposited compounds, and that earthworms have the potential to mitigate negative impacts of pollutants on litter decomposition and ecosystem processes.
RESUMO
Lignocellulose, a kind of biological resource widely existing in nature, which can be transformed into value-added biochemical products through saccharification, fermentation or chemical catalysis. Pretreatments are the necessary step to increase the accessibility and digestibility of lignocellulose. This paper comprehensively reviewed different pretreatment progress of lignocellulose in recent year, including mechanical/thermal, biological, inorganic solvent, organic solvent and unconventional physical-chemical pretreatments, focusing on quantifying the influence of pretreatments on subsequent biomass conversion. In addition, related pretreatment techniques such as genetic engineering, reactor configurations, downstream process and visualization technology of pretreatment were discussed. Finally, this review presented the challenge of lignocellulose pretreatment in the future.
Assuntos
Lignina , Tecnologia , Biomassa , Fermentação , Hidrólise , Lignina/metabolismoRESUMO
To better understand the taxonomy of the genus Oxytropis, we sequenced the complete chloroplast genome of Oxytropis aciphylla Ledeb. The total plastome of O. aciphylla Ledeb. is 122,121 bp in length with a GC content of 34.3%. It contains one large single-copy (LSC) region of 88,235 bp, one small single-copy (SSC) region of 10,400 bp, and one inverted repeat (IR) region of 23,486 bp, encoding 76 proteins, four rRNAs, and 29 tRNAs. The phylogenetic position shows that O. aciphylla Ledeb. is the closest to Oxytropis glabra.
RESUMO
Soil invertebrates and microorganisms are two major drivers of litter decomposition. Even though the importance of invertebrates and microorganisms in biogeochemical soil cycles and soil food webs has been studied, the effects of invertebrates on fungi are not well understood compared to other organisms. In this work, we investigated the effects of soil invertebrates on fungi as a factor that cannot be ignored in the study of nutrient cycling. The result showed the grazing of isopods on white-rot fungi was transitive and persistent. The grazed fungi appeared "compensatory" growing. The biomass of fungi increased after grazing. The activities of enzymes associated with nutrient cycling were increased under grazing. The zymography images showed the enzyme hotspots and activities also increased significantly in the grazing area. The results suggest that invertebrate grazing can significantly increase the fungal biomass and enzyme activity, accelerating litter decomposition in the unreached grazer area. The grazing effects of invertebrate plays an important role in promoting the nutrient cycling of the forest ecosystem. We believe that this study will be a good reference related to showing the relationship between soil invertebrates, fungi and soil biogeochemical cycles.
RESUMO
Solar radiation has been regarded as a driver of litter decomposition in arid and semiarid ecosystems. Photodegradation of litter organic carbon (C) depends on chemical composition and water availability. However, the chemical changes in organic C that respond to solar radiation interacting with water pulses remain unknown. To explain changes in the chemical components of litter organic C exposed to UV-B, UV-A, and photosynthetically active radiation (PAR) mediated by water pulses, we measured the chemistry of marcescent Lindera glauca leaf litter by solid-state 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) over 494 days of litter decomposition with a microcosm experiment. Abiotic and biotic factors regulated litter decomposition via three pathways: first, photochemical mineralization of lignin methoxyl C rather than aromatic C exposed to UV radiation; second, the biological oxidation and leaching of cellulose O-alkyl C exposed to PAR and UV radiation interacts with water pulses; and third, the photopriming effect of UV radiation on lignin aromatic C rather than cellulose O-alkyl C under the interaction between radiation and water pulses. The robust decomposition index that explained the changes in the mass loss was the ratio of aromatic C to O-alkyl C (AR/OA) under radiation, but the ratio of hydrophobic to hydrophilic C (hydrophobicity), the carbohydrate C to methoxyl C ratio (CC/MC), and the alkyl C to O-alkyl C ratio (A/OA) under radiation were mediated by water pulses. Moreover, the photopriming effect and water availability promoted the potential activities of peroxidase and phenol oxidase associated with lignin degradation secreted by fungi. Our results suggest that direct photodegradation of lignin methoxyl C increases microbial accessibility to lignin aromatic C. Photo-oxidized compounds might be an additional C pool to regulate the stability of the soil C pool derived from plant litter by degrading lignin methoxyl and aromatic C.