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1.
Zootaxa ; 4810(3): zootaxa.4810.3.10, 2020 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-33055738

RESUMO

The leaf-litter-inhabiting diparine genus Pseudoceraphron Dodd (Hymenoptera: Pteromalidae) is for the first time recorded to occur in the Northern Hemisphere (Japan) and is confirmed from New Zealand. Pseudoceraphron belissimus sp. n. (Japan: Ishigaki-jima), P. zealandicus sp. n., and P. kepanus sp. n. (both New Zealand: Northern Island) are described.


Assuntos
Himenópteros , Animais , Japão , Nova Zelândia , Folhas de Planta
2.
Zootaxa ; 4759(3): zootaxa.4759.3.8, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-33056911

RESUMO

Drypetothrips korykis gen. et sp.n. is described as inducing leaf-margin galls on a small tree in Australia, Drypetes deplanchei [Putranjivaceae]. This thrips is similar in appearance to the smaller species of the genus Kladothrips that induce galls on Acacia species. The galls are invaded by a phytophagous kleptoparasitic thrips, Pharothrips hynnis gen. et sp.n., females of which have a forked plough-like structure protruding ventrally on the frons that is unique amongst Thysanoptera.


Assuntos
Acacia , Tisanópteros , Animais , Feminino , Folhas de Planta , Árvores
3.
Zootaxa ; 4816(2): zootaxa.4816.2.4, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-33055704

RESUMO

The Australian Acacia-thrips lineage comprises at least 250 species in 30 genera of Phlaeothripinae, all of them known only from Acacia species in Australia. Two new species from two of these genera are described here as the first recorded instances of host-shifting within this diverse thrips lineage, with the host shifts being between unrelated angiosperm orders, from Fabales to Proteales and Myrtales. Brakothrips eucalypti sp. n. is described from the branches of a species of Eucalyptus, and Katothrips banksiae sp. n. is described forming substantial colonies within lepidopterous leaf mines on a species of Banksia. Previously these thrips genera were known only from Acacia species, and comprised seven described species of Brakothrips and 35 described species of Katothrips.


Assuntos
Acacia , Eucalyptus , Tisanópteros , Animais , Austrália , Folhas de Planta
4.
Zootaxa ; 4766(1): zootaxa.4766.1.10, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-33056612

RESUMO

Asteraceae comprises one of the major host plant families for Bucculatricidae and Artemisia is the most exploited host genus, however, not a single record of Bucculatrix species feeding on Asteraceae is confirmed in China. One new species, B. duanwuia Liu, sp. nov., feeding on Artemisia princeps Pamp. (Asteraceae), is described from China, supplemented with illustrations of leaf mines and pupa, biology and DNA barcodes. Bucculatrix notella Seksjaeva, 1996 is recorded for the first time in China and DNA barcodes are provided aiding species separation for the first time.


Assuntos
Artemisia , Mariposas , Animais , China , Folhas de Planta , Pupa
5.
Nat Commun ; 11(1): 4945, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33009378

RESUMO

Spring warming substantially advances leaf unfolding and flowering time for perennials. Winter warming, however, decreases chilling accumulation (CA), which increases the heat requirement (HR) and acts to delay spring phenology. Whether or not this negative CA-HR relationship is correctly interpreted in ecosystem models remains unknown. Using leaf unfolding and flowering data for 30 perennials in Europe, here we show that more than half (7 of 12) of current chilling models are invalid since they show a positive CA-HR relationship. The possible reason is that they overlook the effect of freezing temperature on dormancy release. Overestimation of the advance in spring phenology by the end of this century by these invalid chilling models could be as large as 7.6 and 20.0 days under RCPs 4.5 and 8.5, respectively. Our results highlight the need for a better representation of chilling for the correct understanding of spring phenological responses to future climate change.


Assuntos
Mudança Climática , Temperatura Baixa , Folhas de Planta/fisiologia , Estações do Ano , Betula/fisiologia , Temperatura Alta , Modelos Lineares , Modelos Biológicos
6.
J Contemp Dent Pract ; 21(7): 733-740, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33020355

RESUMO

AIM: Phytomedicine has been commonly practiced as a form of traditional medicine in various cultures for the treatment of oral diseases. Recently, it has gained importance as an alternative to conventional treatment. Several extracts of plants and fruits have been recently evaluated for their potential activity against microorganisms involved in the development of dental caries. The purpose of this study was to evaluate the antimicrobial activity and antiadherent effect of the crude organic extract (COE) and three partitions (aqueous, butanolic, and chloroformic) of Psidium guajava (guava) leaves on a cariogenic biofilm model. MATERIALS AND METHODS: Guava leaves were obtained from the mountains of northern Peru, where they grow wild and free of pesticides. The antimicrobial activity of the COEs and partitions against Streptococcus mutans and Streptococcus gordonii was determined by measuring the inhibition halos, while the effect on biofilm adhesion was determined by measuring the optical density using spectrophotometry. RESULTS: An antibacterial effect of the COE and chloroformic partition against S. gordonii (p < 0.05) was found, as was a significant effect on biofilm adherence, with a minimum inhibitory concentration (MIC) of 0.78 mg/mL, which was maintained throughout the 7 days of evaluation. CONCLUSION: We conclude that the COEs and their chloroformic partition have antimicrobial and antibiotic effects against this strain of S. gordonii, making them of particular interest for evaluation as a promising alternative for the prevention of dental caries. CLINICAL SIGNIFICANCE: By knowing the antimicrobial effect of Psidium guajava, this substance can be effectively used in products aimed to prevent dental caries and periodontal disease.


Assuntos
Anti-Infecciosos/farmacologia , Cárie Dentária/tratamento farmacológico , Psidium , Biofilmes , Humanos , Peru , Folhas de Planta
7.
Am J Bot ; 107(9): 1260-1273, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32984956

RESUMO

PREMISE: Defense investment in plant reproductive structures is relatively understudied compared to the defense of vegetative organs. Here the evolution of chemical defenses in reproductive structures is examined in light of the optimal defense, apparency, and resource availability hypotheses within the genus Cornus using a phylogenetic comparative approach in relation to phenology and native habitat environmental data. METHODS: Individuals representing 25 Cornus species were tracked for reproductive phenology over a full growing season at the Arnold Arboretum of Harvard University. Floral, fruit, and leaf tissue was sampled to quantify defensive chemistry as well as fruit nutritional traits relevant to bird dispersal. Native habitat environmental characteristics were estimated using locality data from digitized herbarium records coupled with global soil and climate data sets. RESULTS: The evolution of later flowering was correlated with increased floral tannins, and the evolution of later fruiting was correlated with increased total phenolics. Leaves were found to contain the highest tannin activity, while inflorescences contained the highest total flavonoids. Multiple aspects of fruit defensive chemistry were correlated with fruit nutritional traits. Floral and fruit defensive chemistry were evolutionarily correlated with aspects of native habitat temperature, precipitation, and soil characteristics. CONCLUSIONS: Results provide tentative support for the apparency hypothesis with respect to both flower and fruit phenology, while relative concentrations of secondary metabolites across organs provide mixed support for the optimal defense hypothesis. The evolution of reproductive defense with native habitat provides, at best, mixed support for the resource availability hypothesis.


Assuntos
Cornus , Animais , Flores , Frutas , Inflorescência , Filogenia , Folhas de Planta
8.
Proc Biol Sci ; 287(1935): 20201080, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32933440

RESUMO

Plant guttation is a fluid from xylem and phloem sap secreted at the margins of leaves from many plant species. All previous studies have considered guttation as a water source for insects. Here, we hypothesized that plant guttation serves as a reliable and nutrient-rich food source for insects with effects on their communities. Using highbush blueberries as a study system, we demonstrate that guttation droplets contain carbohydrates and proteins. Insects from three feeding lifestyles, a herbivore, a parasitic wasp and a predator, increased their longevity and fecundity when fed on these guttation droplets compared to those fed on control water. Our results also show that guttation droplets, unlike nectar, are present on leaves during the entire growing season and are visited by numerous insects of different orders. In exclusion-field experiments, the presence of guttation modified the insect community by increasing the number of predators and parasitic wasps that visited the plants. Overall, our results demonstrate that plant guttation is highly reliable, compared to other plant-derived food sources such as nectar, and that it increases the communities and fitness of insects. Therefore, guttation represents an important plant trait with profound implications on multi-trophic insect-plant interactions.


Assuntos
Herbivoria , Insetos , Folhas de Planta , Xilema , Animais , Nutrientes
9.
Toxins (Basel) ; 12(9)2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32957454

RESUMO

The deadly pandemic named COVID-19, caused by a new coronavirus (SARS-CoV-2), emerged in 2019 and is still spreading globally at a dangerous pace. As of today, there are no proven vaccines, therapies, or even strategies to fight off this virus. Here, we describe the in silico docking results of a novel broad range anti-infective fusion protein RTAM-PAP1 against the various key proteins of SARS-CoV-2 using the latest protein-ligand docking software. RTAM-PAP1 was compared against the SARS-CoV-2 B38 antibody, ricin A chain, a pokeweed antiviral protein from leaves, and the lectin griffithsin using the special CoDockPP COVID-19 version. These experiments revealed novel binding mechanisms of RTAM-PAP1 with a high affinity to numerous SARS-CoV-2 key proteins. RTAM-PAP1 was further characterized in a preliminary toxicity study in mice and was found to be a potential therapeutic candidate. These findings might lead to the discovery of novel SARS-CoV-2 targets and therapeutic protein structures with outstanding functions.


Assuntos
Antivirais/química , Antivirais/uso terapêutico , Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Pneumonia Viral/tratamento farmacológico , Ligação Proteica/efeitos dos fármacos , Proteínas Inativadoras de Ribossomos Tipo 1/química , Proteínas Inativadoras de Ribossomos Tipo 1/uso terapêutico , Ricina/uso terapêutico , Animais , Simulação por Computador , Humanos , Camundongos , Modelos Animais , Pandemias , Phytolacca americana/química , Folhas de Planta/química , Proteínas Inativadoras de Ribossomos Tipo 1/genética
10.
Chemosphere ; 254: 126794, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957267

RESUMO

Present study carried out pot experiments and evaluated effects of single and binary mixture of nanoparticles (exposed via sludge as soil conditioner) on spinach plant. Exposure of Ag2O nanoparticles (NPs) (1 and 10 mg/kg soil-sludge) did not show significant reduction in plant as compared to control. On the other hand, TiO2 NPs (exposed as single and in binary mixture) resulted in significant increase in root length (29% and 37%) and fresh weight (60% and 48%) at highest exposure concentration. Total chlorophyll content decreased for Ag2O and binary mixture (7% and 4%, respectively) and increased for TiO2 (5%) at 10 mg/kg soil-sludge. The toxic interaction between Ag2O and TiO2 NPs was additive at both exposure concentrations. Ag2O NPs had higher tendency of root surface adsorption than TiO2 NPs. Metal content in spinach leaves at highest exposure concentration was Ag: 2.6 ± 0.55 mg/g plant biomass(for Ag2O NPs) and 1.02 ± 0.32 mg/g plant biomass (for Ag2O + TiO2 NPs) and for Ti: 1.12 ± 0.78 (for TiO2 NPs) mg/g plant biomass and 0.58 ± 0.41 mg/g (for Ag2O + TiO2 NPs). The inadvertent ingestion of NPs- contaminated spinach resulted in projected daily intake (DI) of Ag and Ti for different age-mass classes (child to adult) exceeding the oral reference dose for toxicity during oral ingestion. In conclusion, we report no acute toxicity of single and binary mixture of NPs to spinach but significant accumulation of Ag and Ti metals in spinach leaves. There are high chances that ingestion of spinach grown in such environment might lead to human health risks.


Assuntos
Nanopartículas/toxicidade , Poluentes do Solo/toxicidade , Spinacia oleracea/efeitos dos fármacos , Biomassa , Clorofila , Humanos , Nanopartículas Metálicas/toxicidade , Metais/toxicidade , Nanopartículas/análise , Folhas de Planta/química , Esgotos , Solo , Poluentes do Solo/análise , Spinacia oleracea/crescimento & desenvolvimento , Titânio/farmacologia
11.
Ecotoxicol Environ Saf ; 203: 111010, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888587

RESUMO

Manganese (Mn) toxicity is common in plants grown on very acid soils. However, some plants species that grow in this condition can take up high amounts of Mn and are referred to as hyperaccumulating species. In this study, we evaluated the capacity of Ilex paraguariensis to accumulate Mn and the effect of excessive concentrations on plant growth and nutrition. For this, a container experiment was conducted using soils from different parent materials (basalt and sandstone), with and without liming, and at six doses of applied Mn (0, 30, 90, 270, 540 and 1,080 mg kg-1). Clonal plants grown for 203 days were harvested to evaluate yield, and leaf tissue samples were evaluated for Mn and other elements. Without liming and with high Mn doses, leaf Mn concentrations reached 13,452 and 12,127 mg kg-1 in sandstone and basalt soils, respectively; concentrations in excess of 10,000 mg kg-1 are characteristic of hyperaccumulating plants. Liming reduced these values to 7203 and 8030 mg kg-1. More plant growth accompanied increased Mn leaf concentrations, with a growth reduction noted at the highest dose in unlimed soils. Elemental distribution showed Mn presence in the mesophyll, primarily in vascular bundles, without high Mn precipitates. Interveinal chlorosis of young leaves associated with high Mn concentration and lower Fe concentrations was observed, especially in sandstone soil without liming. However, the occurrence of this symptom was not associated with decreased plant growth.


Assuntos
Ácidos/farmacologia , Ilex paraguariensis/metabolismo , Manganês/metabolismo , Doenças das Plantas/induzido quimicamente , Poluentes do Solo/metabolismo , Ácidos/análise , Compostos de Cálcio/análise , Compostos de Cálcio/farmacologia , Ilex paraguariensis/efeitos dos fármacos , Ilex paraguariensis/crescimento & desenvolvimento , Ferro/metabolismo , Manganês/análise , Manganês/toxicidade , Óxidos/análise , Óxidos/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
12.
Nat Commun ; 11(1): 4519, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908150

RESUMO

The leaf economics spectrum (LES) describes consistent correlations among a variety of leaf traits that reflect a gradient from conservative to acquisitive plant strategies. So far, whether the LES holds in wetland plants at a global scale has been unclear. Using data on 365 wetland species from 151 studies, we find that wetland plants in general show a shift within trait space along the same common slope as observed in non-wetland plants, with lower leaf mass per area, higher leaf nitrogen and phosphorus, faster photosynthetic rates, and shorter leaf life span compared to non-wetland plants. We conclude that wetland plants tend to cluster at the acquisitive end of the LES. The presented global quantifications of the LES in wetland plants enhance our understanding of wetland plant strategies in terms of resources acquisition and allocation, and provide a stepping-stone to developing trait-based approaches for wetland ecology.


Assuntos
Fotossíntese/genética , Folhas de Planta/genética , Plantas/genética , Áreas Alagadas , Nitrogênio/análise , Fósforo/análise , Folhas de Planta/anatomia & histologia , Folhas de Planta/química , Plantas/anatomia & histologia , Plantas/metabolismo
13.
Rev Soc Bras Med Trop ; 53: e20200176, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32935784

RESUMO

INTRODUCTION: Curtailing the development of the aquatic immature stages of Aedes aegypti is one of the main measures to limit their spread and the diseases transmitted by them. The use of plant extracts is a promising approach in the development of natural insecticides. Thus, this research aimed to characterize the inhibitory effect of the hydroalcoholic extract of Caryocar brasiliense leaves on the emergence of adult A. aegypti and the main substances that constitute this extract. METHODS: C. brasiliense leaf extract was prepared by ethanol (70%) extraction. Bioassays using L3 larvae were performed at concentrations of 200, 300, 400, and 500 ppm. We identified the major secondary metabolites present in this extract, and performed toxicity tests on an off-target organism, Danio rerio. RESULTS: We observed a significant delay in the development of A. aegypti larvae mainly at a concentration of 500 ppm, and estimated an emergence inhibition for 50% of the population of 150 ppm. Moreover, the C. brasiliense leaf extracts exhibited low toxicity in D. rerio. The main compounds found in the extract were quercetin, violaxanthin, myricetin3-O-hexoside, methyl-elagic-3-arabinose acid, and isoquercitrin. CONCLUSIONS: Herein, we demonstrate the inhibition of mosquito development by the hydroalcoholic extract of C. brasiliense and suggest substances that may act as active principles.


Assuntos
Aedes , Animais , Inseticidas , Larva , Extratos Vegetais , Folhas de Planta
14.
Anticancer Res ; 40(9): 5201-5210, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32878808

RESUMO

BACKGROUND/AIM: Persimmon (Diospyros kaki L.) leaves are popular as a tea infusion in Asia and their main active ingredients are flavonoids. The present study aimed to explore the anticancer properties of flavonoids isolated from persimmon leaves (PLF). MATERIALS AND METHODS: We investigated the in vitro anti-proliferative activity of PLF against several human cancer cell lines. Apoptosis and intracellular reactive oxygen species (ROS) induced by PLF were accessed using high-content analysis with florescent staining. The ability of PLF to scavenge free radicals was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. RESULTS: PLF demonstrated significant inhibition of proliferation of liver, breast, and colorectal cancer cells in vitro. PLF induced apoptosis and increased intracellular ROS levels in HCT116 (colorectal cancer) and HepG2 (liver cancer) cells. In addition, PLF showed strong free radical scavenging ability. CONCLUSION: The anti-proliferation activity of PLF against cancer cells was related to the induction of apoptosis and oxidative stress.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Diospyros/química , Flavonoides/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Folhas de Planta/química , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antioxidantes/química , Antioxidantes/farmacologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Flavonoides/química , Flavonoides/isolamento & purificação , Humanos , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Espécies Reativas de Oxigênio/metabolismo
15.
Georgian Med News ; (304-305): 153-157, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32965267

RESUMO

The research objectives were to study the introduction process of different aromatic and spice plants in the Batumi Botanical Garden and the content of bioactive compounds in aromatic plants introduced and grown in the soil and climatic conditions of the garden.; Among the aromatic plants introduced to the BBG by the authors, the following species are having full vegetative and generative development in the open ground:Cuminum cyminum L.; Polianthes tuberosa L.; Iris pallida Lam.;Geranium macrorrhizum L., Piper suaveolens Ham., Piper piperita L., Thymus citriodorus Schreb., Satureja Montana L., Mentha piperita L., Origanum vulgare L., Mentha longifolia L., Hyssopus officinalis L.; Phyla scaberrima Moldenke, Ruta graveolens L.; Vegetative organs reach the full development, but without blooming:Curcuma longa L..; Zingiber officinale Roscoe.; Elettaria cardamomum Maton.; Coffea arabica L.; Coffea conephera L..; Vanilla planifolia Jacks.; Cassia acutifolia Delile.; For the purpose of studying the content of bioactive compounds in plants introduced to the soil and climatic conditions of the BBG with the help of green technologies, the following species were taken for analysis:Cassia acutifolia Delile. - seed, flower, leaf; Cuminum cyminum L. - seed; Coffea conefera L. andCoffea Arabica L., leaves and seeds; Vanilla planifolia Jacks. - leaves; Elletaria cardamomum Maton. -Cardamom leaves.With the help of gas chromatography - mass spectrometry GC-MS method, there were identified bioactive compounds of various classes. The content of essential oils is identified in all research objects.


Assuntos
Óleos Voláteis , Satureja , Jardins , Cromatografia Gasosa-Espectrometria de Massas , Folhas de Planta
16.
Phytochemistry ; 178: 112463, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32888669

RESUMO

Ten undescribed alkaloids, named integerrines A-J, including one racemic heterodimer of carbazole and indole, two racemic, two scalemic, and one enantiomerically enriched biscarbazoles, two aldoximes, and one racemic pyrrolone, were isolated from the dried leaves and stems of Micromelum integerrimum. The racemic or scalemic compounds were resolved using chiral-phase HPLC and their configurations were determined by comparison of experimental and calculated ECD data. Four compounds exhibited moderate to weak cytotoxicities against HepG2, HTC-116, HeLa, and PANC-1 cell lines, with IC50 values of 14.1-67.5 µM.


Assuntos
Alcaloides , Antineoplásicos , Rutaceae , Linhagem Celular Tumoral , Humanos , Estrutura Molecular , Folhas de Planta
17.
Zhongguo Zhong Yao Za Zhi ; 45(16): 3826-3836, 2020 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-32893577

RESUMO

Magnolia officinalis is a traditional Chinese medicine,with many years of cultivating process, M. officinalis leaves show more differentiation types due to the exchange of seeds from different provenances. "Da Ao"(DA), "Xiao Ao"(XA), "Chuan Hou"(CH),and "Liu Ye"(LY)are the main types of M. officinalis in Sichuan province of China,and there were obvious differences in growth rate,chemical composition,leaf shape and leaf colour. This study selected different types of M. officinalis leaves(DA,XA,LY and CH)from Sichuan to determine their chlorophyll content. Transcriptomic level sequencing of different types of M. officinalis leaf tissues was by high-throughput sequencing analysis and proteomics used an integrated approach involving TMT labelling and LC-MS/MS to quantify the dynamic changes of the whole proteome of M. officinalis. The results showed that CH had the lowest chlorophyll content while DA had the highest chlorophyll content. Furthermore,transcriptome and proteomics results showed that chlorophyll synthesis pathway in DA glutamine-tRNA reductase,urinary porphyrins decarboxylase(UROD),oxygen-dependent protoporphyrin(ODCO),the original-Ⅲ oxidase protoporphyrin oxidase(PPO),magnesium chelating enzyme subunit ChlD,protoporphyrin magnesium Ⅸ monomethyl ester [oxidative] cyclase(MPPMC)were significantly higher than CH,XA and LY,consistent in the results of determination of chlorophyll content(chlorophyll content was highest of 37.56 mg·g~(-1) FW). Some rate-limiting enzymes related to the chlorophyll synthesis,such as ODCO,PPO and MPPMC were tested by Parallel Reaction Monitoring(PRM),and the results showed that the rate-limiting enzyme content in DA was higher than that in other three types. Therefore,based on the differences in leaf color of four types of M. officinalis,the research conducted a preliminary study on the chlorophyll metabolism pathway in leaves of different types of M. officinalis,and explored relevant genes and proteins causing leaf color differences from the molecular level,so as to lay a foundation for studying the differences in growth and development of different types of M. officinalis.


Assuntos
Magnolia , China , Clorofila , Cromatografia Líquida , Folhas de Planta , Proteoma , Espectrometria de Massas em Tandem , Transcriptoma
18.
Sci Total Environ ; 740: 139740, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32927530

RESUMO

Most wetlands have been subject to changes in flooding regimes by climate change and human activities, resulting in widespread alteration of wetland plants at different organizational levels. However, scaling the responses of wetland plants to changes in flooding regimes is still challenging, because flooding could indirectly affect wetland plants through affecting environment factors (e.g. soil properties). During the non-flooding period, we investigated leaf N and P stoichiometry at three organizational levels (intra-species, inter-species, inter-community) along a flooding duration gradient in a lakeshore meadow of Poyang Lake floodplain, China. At the intra-species level, leaf N and P stoichiometry showed species-specific responses to flooding duration. At the inter-species level, leaf N or P contents or N:P ratio showed no significant response to flooding duration. At the inter-community level, leaf N and P contents significantly increased with flooding duration, while leaf N:P ratio decreased. At each organizational level, leaf N and P stoichiometry showed poor correlation with soil N and P stoichiometry. Moreover, intra-specific responses of leaf N and P contents to flooding duration and soil nutrient content increased with mean flooding duration of species distribution, which was the index of species hydrological niche. Intraspecific variation had lower contribution than species turnover to variations in community leaf nutrient stoichiometry. In all, flooding duration affected leaf N and P stoichiometry mainly through direct pathway at the intra-species and inter-community level, rather than the indirect pathway via soil nutrient stoichiometry. Therefore, our results have implications for scaling up from environmental conditions to ecosystem processes via wetland plant communities.


Assuntos
Ecossistema , Nitrogênio/análise , China , Nutrientes , Fósforo , Folhas de Planta/química , Solo
19.
Am J Bot ; 107(8): 1165-1176, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32864740

RESUMO

PREMISE: Within closed-canopy forests, vertical gradients of light and atmospheric CO2 drive variations in leaf carbon isotope ratios, leaf mass per area (LMA), and the micromorphology of leaf epidermal cells. Variations in traits observed in preserved or fossilized leaves could enable inferences of past forest canopy closure and leaf function and thereby habitat of individual taxa. However, as yet no calibration study has examined how isotopic, micro- and macromorphological traits, in combination, reflect position within a modern closed-canopy forest or how these could be applied to the fossil record. METHODS: Leaves were sampled from throughout the vertical profile of the tropical forest canopy using the 48.5 m crane at the Daintree Rainforest Observatory, Queensland, Australia. Carbon isotope ratios, LMA, petiole metric (i.e., petiole-width2 /leaf area, a proposed proxy for LMA that can be measured from fossil leaves), and leaf micromorphology (i.e., undulation index and cell area) were compared within species across a range of canopy positions, as quantified by leaf area index (LAI). RESULTS: Individually, cell area, δ13 C, and petiole metric all correlated with both LAI and LMA, but the use of a combined model provided significantly greater predictive power. CONCLUSIONS: Using the observed relationships with leaf carbon isotope ratio and morphology to estimate the range of LAI in fossil floras can provide a measure of canopy closure in ancient forests. Similarly, estimates of LAI and LMA for individual taxa can provide comparative measures of light environment and growth strategy of fossil taxa from within a flora.


Assuntos
Floresta Úmida , Árvores , Austrália , Calibragem , Fósseis , Fotossíntese , Folhas de Planta , Queensland
20.
Am J Bot ; 107(8): 1136-1147, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32864741

RESUMO

PREMISE: Mortality events involving drought and pathogens in natural plant systems are on the rise due to global climate change. In Santa Barbara, California, United States, big berry manzanita (Arctostaphylos glauca) has experienced canopy dieback related to a multi-year drought and infection from fungal pathogens in the Botryosphaeriaceae family. A greenhouse experiment was conducted using Neofusicoccum australe to test the specific influences of drought and fungal infection on A. glauca. METHODS: A full factorial design was used to compare four treatment groups (drought + inoculation; drought - inoculation; watering + inoculation; and control: watering - inoculation). Data were collected for 10 weeks on stress symptoms, changes in leaf fluorescence and photosynthesis, and mortality. RESULTS: Results indicated significant effects of watering and inoculation treatments on net photosynthesis, dark-adapted fluorescence, and disease symptom severity (P < 0.05), and a strong correlation was found between physiological decline and visible stress (P < 0.0001). Mortality differed between treatments, with all groups except for the control experiencing mortality (43% mortality in drought - inoculation, 83% in watering - inoculation, and 100% in drought + inoculation). A Kaplan-Meier survival analysis showed drought + inoculation to have the least estimated survivorship compared to all other treatment groups. CONCLUSIONS: In addition to a possible synergistic interaction between drought and fungal infection in disease onset and mortality rates in A. glauca, these results indicate that young, non-drought-stressed plants are susceptible to mortality from N. australe infection, with important implications for the future of wildland shrub communities.


Assuntos
Arctostaphylos , Ascomicetos , Secas , Fotossíntese , Folhas de Planta
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