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1.
Nat Commun ; 11(1): 4663, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938914

RESUMO

Scientific understanding of biodiversity dynamics, resulting from past climate oscillations and projections of future changes in biodiversity, has advanced over the past decade. Little is known about how these responses, past or future, are spatially connected. Analyzing the spatial variability in biodiversity provides insight into how climate change affects the accumulation of diversity across space. Here, we evaluate the spatial variation of phylogenetic diversity of European seed plants among neighboring sites and assess the effects of past rapid climate changes during the Quaternary on these patterns. Our work shows a marked homogenization in phylogenetic diversity across Central and Northern Europe linked to high climate change velocity and large distances to refugia. Our results suggest that the future projected loss in evolutionary heritage may be even more dramatic, as homogenization in response to rapid climate change has occurred among sites across large landscapes, leaving a legacy that has lasted for millennia.


Assuntos
Filogenia , Fenômenos Fisiológicos Vegetais , Biodiversidade , Mudança Climática , Europa (Continente) , Plantas/genética , Refúgio de Vida Selvagem , Sementes
2.
PLoS One ; 15(8): e0234166, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797098

RESUMO

Response to simultaneous stressors is an important facet of plant ecology and land management. In a greenhouse trial, we studied how eight plant species responded to single and combined effects of three soil concentrations of the phytotoxic munitions constituent RDX and two levels of water-resourcing. In an outdoor trial, we studied the effects of high RDX soil concentration and two levels of water-resourcing in three plant species. Multiple endpoints related to RDX fate, plant health, and plant survival were evaluated in both trials. Starting RDX concentration was the most frequent factor influencing all endpoints. Water-resourcing also had significant impacts, but in fewer cases. For most endpoints, significant interaction effects between RDX concentration and water-resourcing were observed for some species and treatments. Main and interaction effects were typically variable (significant in one treatment, but not in another; associated with increasing endpoint values for one treatment and/or with decreasing endpoint values in another). This complexity has implications for understanding how RDX and water-availability combine to impact plants, as well as for applications like phytoremediation. As an additional product of these greenhouse and outdoor trials, three plants native or naturalized within the southeastern United States were identified as promising species for further study as in situ phytoremediation resources. Plumbago auriculata exhibited relatively strong and markedly consistent among-treatment mean proportional reductions in soil RDX concentrations (112% and 2.5% of the means of corresponding values observed within other species). Likewise, across all treatments, Salvia coccinea exhibited distinctively low variance in mean leaf chlorophyll content index levels (6.5% of the means of corresponding values observed within other species). Both species also exhibited mean wilting and chlorosis levels that were 66% and 35%, and 67% and 84%, of corresponding values observed in all other plants, respectively. Ruellia caroliniensis exhibited at least 43% higher mean survival across all treatments than any other test species in outdoor trials, despite exhibiting similar RDX uptake and bioconcentration levels.


Assuntos
Substâncias Explosivas/toxicidade , Plantas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Triazinas/toxicidade , Acanthaceae/efeitos dos fármacos , Acanthaceae/crescimento & desenvolvimento , Acanthaceae/fisiologia , Biodegradação Ambiental , Substâncias Explosivas/administração & dosagem , Substâncias Explosivas/farmacocinética , Instalações Militares , Desenvolvimento Vegetal/efeitos dos fármacos , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Plumbaginaceae/efeitos dos fármacos , Plumbaginaceae/crescimento & desenvolvimento , Plumbaginaceae/fisiologia , Salvia/efeitos dos fármacos , Salvia/crescimento & desenvolvimento , Salvia/fisiologia , Poluentes do Solo/administração & dosagem , Poluentes do Solo/farmacocinética , Sudeste dos Estados Unidos , Estresse Fisiológico/efeitos dos fármacos , Triazinas/administração & dosagem , Poluentes Químicos da Água/administração & dosagem , Poluentes Químicos da Água/farmacocinética , Poluentes Químicos da Água/toxicidade , Recursos Hídricos
3.
Nat Commun ; 11(1): 3999, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32778648

RESUMO

Land use change, by disrupting the co-evolved interactions between plants and their pollinators, could be causing plant reproduction to be limited by pollen supply. Using a phylogenetically controlled meta-analysis on over 2200 experimental studies and more than 1200 wild plants, we ask if land use intensification is causing plant reproduction to be pollen limited at global scales. Here we report that plants reliant on pollinators in urban settings are more pollen limited than similarly pollinator-reliant plants in other landscapes. Plants functionally specialized on bee pollinators are more pollen limited in natural than managed vegetation, but the reverse is true for plants pollinated exclusively by a non-bee functional group or those pollinated by multiple functional groups. Plants ecologically specialized on a single pollinator taxon were extremely pollen limited across land use types. These results suggest that while urbanization intensifies pollen limitation, ecologically and functionally specialized plants are at risk of pollen limitation across land use categories.


Assuntos
Ecologia , Fenômenos Fisiológicos Vegetais , Pólen , Polinização , Animais , Abelhas , Bases de Dados Factuais , Ecossistema , Filogenia , Plantas/classificação , Urbanização
4.
J Environ Radioact ; 222: 106375, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32791372

RESUMO

The purpose of this work is to highlight the effects of ionizing radiation on the genetic material in higher plants by assessing both adaptive processes as well as the evolution of plant species. The effects that the ionizing radiation has on greenery following a nuclear accident, was examined by taking the Chernobyl Nuclear Power Plant disaster as a case study. The genetic and evolutionary effects that ionizing radiation had on plants after the Chernobyl accident were highlighted. The response of biota to Chernobyl irradiation was a complex interaction among radiation dose, dose rate, temporal and spatial variation, varying radiation sensitivities of the different plants' species, and indirect effects from other events. Ionizing radiation causes water radiolysis, generating highly reactive oxygen species (ROS). ROS induce the rapid activation of detoxifying enzymes. DeoxyriboNucleic Acid (DNA) is the object of an attack by both, the hydroxyl ions and the radiation itself, thus triggering a mechanism both direct and indirect. The effects on DNA are harmful to the organism and the long-term development of the species. Dose-dependent aberrations in chromosomes are often observed after irradiation. Although multiple DNA repair mechanisms exist, double-strand breaks (DSBs or DNA-DSBs) are often subject to errors. Plants DSBs repair mechanisms mainly involve homologous and non-homologous dependent systems, the latter especially causing a loss of genetic information. Repeated ionizing radiation (acute or chronic) ensures that plants adapt, demonstrating radioresistance. An adaptive response has been suggested for this phenomenon. As a result, ionizing radiation influences the genetic structure, especially during chronic irradiation, reducing genetic variability. This reduction may be associated with the fact that particular plant species are more subject to chronic stress, confirming the adaptive theory. Therefore, the genomic effects of ionizing radiation demonstrate their likely involvement in the evolution of plant species.


Assuntos
Adaptação Fisiológica , Acidente Nuclear de Chernobyl , Desastres , Fenômenos Fisiológicos Vegetais , Monitoramento de Radiação , Radioatividade , Plantas , Radiação Ionizante
5.
Nat Commun ; 11(1): 4180, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826915

RESUMO

Ecologists have long argued that higher functioning in diverse communities arises from the niche differences stabilizing species coexistence and from the fitness differences driving competitive dominance. However, rigorous tests are lacking. We couple field-parameterized models of competition between 10 annual plant species with a biodiversity-functioning experiment under two contrasting environmental conditions, to study how coexistence determinants link to biodiversity effects (selection and complementarity). We find that complementarity effects positively correlate with niche differences and selection effects differences correlate with fitness differences. However, niche differences also contribute to selection effects and fitness differences to complementarity effects. Despite this complexity, communities with an excess of niche differences (where niche differences exceeded those needed for coexistence) produce more biomass and have faster decomposition rates under drought, but do not take up nutrients more rapidly. We provide empirical evidence that the mechanisms determining coexistence correlate with those maximizing ecosystem functioning.


Assuntos
Biodiversidade , Biomassa , Ecossistema , Modelos Biológicos , Fenômenos Fisiológicos Vegetais , Desenvolvimento Vegetal , Plantas/classificação , Dinâmica Populacional , Espanha
6.
PLoS One ; 15(8): e0235469, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845880

RESUMO

Random sampling is an important approach to field vegetation surveys. However, sampling surveys in desert areas are difficult because determining an appropriate quadrat size that represent the sparse and unevenly distributed vegetation is challenging. In this study, we present a methodology for quadrat size optimization based on low-altitude high-precision unmanned aerial vehicle (UAV) images. Using the Daliyaboyi Oasis as our study area, we simulated random sampling and analyzed the frequency distribution and variation in the fractional vegetation cover (FVC) index of the samples. Our results show that quadrats of 50 m × 50 m size are the most representative for sampling surveys in this location. The method exploits UAV technology to rapidly acquire vegetation information and overcomes the shortcomings of traditional methods that rely on labor-intensive fieldwork to collect species-area relationship (SAR) data. Our method presents two major advantages: (1) speed and efficiency stemming from the application of UAV, which also effectively overcomes the difficulties posed in vegetation surveys by the challenging desert climate and terrain; (2) the large sample size enabled by the use of a sampling simulation. Our methodology is thus highly suitable for selecting the optimal quadrat size and making accurate estimates, and can improve the efficiency and accuracy of field vegetation sampling surveys.


Assuntos
Clima Desértico , Monitorização de Parâmetros Ecológicos/métodos , Fenômenos Fisiológicos Vegetais , Biodiversidade , Biomassa , Monitorização de Parâmetros Ecológicos/instrumentação , Monitorização de Parâmetros Ecológicos/normas , Tecnologia de Sensoriamento Remoto/instrumentação , Tamanho da Amostra
7.
Proc Natl Acad Sci U S A ; 117(30): 18110-18118, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32669427

RESUMO

Mechanical patterns control a variety of biological processes in plants. The microviscosity of cellular structures effects the diffusion rate of molecules and organelles, thereby affecting processes such as metabolism and signaling. Spatial variations in local viscosity are also generated during fundamental events in the cell life cycle. While crucial to a complete understanding of plant mechanobiology, resolving subcellular microviscosity patterns in plants has remained an unsolved challenge. We present an imaging microviscosimetry toolbox of molecular rotors that yield complete microviscosity maps of cells and tissues, specifically targeting the cytosol, vacuole, plasma membrane, and wall of plant cells. These boron-dipyrromethene (BODIPY)-based molecular rotors are rigidochromic by means of coupling the rate of an intramolecular rotation, which depends on the mechanics of their direct surroundings, with their fluorescence lifetime. This enables the optical mapping of fluidity and porosity patterns in targeted cellular compartments. We show how apparent viscosity relates to cell function in the root, how the growth of cellular protrusions induces local tension, and how the cell wall is adapted to perform actuation surrounding leaf pores. These results pave the way to the noninvasive micromechanical mapping of complex tissues.


Assuntos
Modelos Biológicos , Células Vegetais , Fenômenos Fisiológicos Vegetais , Viscosidade , Corantes Fluorescentes/química , Proteínas Motores Moleculares/metabolismo , Sondas Moleculares/química , Especificidade de Órgãos , Organelas/metabolismo
8.
Nat Commun ; 11(1): 3201, 2020 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-32581263

RESUMO

Humans cultivate thousands of economic plants (i.e. plants with economic value) outside their native ranges. To analyze how this contributes to naturalization success, we combine global databases on economic uses and naturalization success of the world's seed plants. Here we show that naturalization likelihood is 18 times higher for economic than non-economic plants. Naturalization success is highest for plants grown as animal food or for environmental uses (e.g. ornamentals), and increases with number of uses. Taxa from the Northern Hemisphere are disproportionately over-represented among economic plants, and economic plants from Asia have the greatest naturalization success. In regional naturalized floras, the percentage of economic plants exceeds the global percentage and increases towards the equator. Phylogenetic patterns in the naturalized flora partly result from phylogenetic patterns in the plants we cultivate. Our study illustrates that accounting for the intentional introduction of economic plants is key to unravelling drivers of plant naturalization.


Assuntos
Agricultura , Espécies Introduzidas/economia , Fenômenos Fisiológicos Vegetais , Agricultura/economia , Biodiversidade , Conservação dos Recursos Naturais , Geografia , Filogenia , Plantas/classificação , Sementes/classificação , Sementes/fisiologia , Especificidade da Espécie
9.
PLoS One ; 15(6): e0220598, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32579545

RESUMO

Roof greening is an important national policy for maintaining the hydrological balance in China; however, plant growth is limited by drought stress. This study aims to identify strong drought resistant plant species for roof greening from ten common species: Paeonia lactiflora, Hemerocallis dumortieri, Meehania urticifolia, Iris lactea var. chinensis, Hylotelephium erythrostictum, Sedum lineare, Iris germanica, Cosmos bipinnata, Hosta plantaginea, and Dianthus barbatus. By controlling the soil relative water content (RWC), we designed three treatments: moderate drought stress (40±2% < RWC < 45±2%), severe drought stress (RWC < 30±2%) and well-watered control (RWC > 75±2%). After the seedlings were provided different levels of water, their membrane permeability (MP), chlorophyll concentration (Chl), and superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) activity were measured. Finally, the membership function method was used to assess the drought resistance of these species. The results showed that C. bipinnata and M. urticifolia were not suitable for moderate or severe drought stress and did not survive. The other species presented variations in physiological and biochemical parameters. The MP of He. dumortieri, I. lactea and Ho. plantaginea showed minor changes between the well-watered control and drought stress. Most of the species showed reduced SOD activity under moderate drought stress but increased activity under severe stress. All of the plant species showed decreases in the protective enzymes POD and APX with increasing drought stress. The membership function method was applied to calculate the plant species' drought resistance, and the following order of priority of the roof-greening plant species was suggested: He. dumortieri > I. germanica > I. lactea > D. barbatus > Hy. erythrostictum > S. lineare > Ho. plantaginea > P. lactiflora.


Assuntos
Secas , Fenômenos Fisiológicos Vegetais , Plântula/fisiologia , Estresse Fisiológico , Ascorbato Peroxidases/metabolismo , Permeabilidade da Membrana Celular , Clorofila/metabolismo , Peroxidases/metabolismo , Plântula/metabolismo , Solo/química , Superóxido Dismutase/metabolismo , Análise de Sobrevida , Água/análise
10.
Physiol Plant ; 170(2): 218-226, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32479663

RESUMO

Melatonin is widely involved in plant growth and stress responses as a master regulator. Melatonin treatment alters the levels of endogenous nitric oxide (NO) and NO affects endogenous melatonin content. Melatonin and NO may induce various plant physiological behavior through interaction mechanism. However, the interactions between melatonin and NO in plants are largely unknown. The review presented the metabolism of endogenous melatonin and NO and their relationship in plants. The interactions between melatonin and NO in plant growth and development and responses to environmental stress were summarized. The molecular mechanisms of interaction between melatonin and NO in plants were also proposed.


Assuntos
Melatonina , Desenvolvimento Vegetal , Óxido Nítrico , Fenômenos Fisiológicos Vegetais , Plantas , Estresse Fisiológico
11.
Proc Natl Acad Sci U S A ; 117(24): 13580-13587, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32482870

RESUMO

Thermal macrophysiology is an established research field that has led to well-described patterns in the global structuring of climate adaptation and risk. However, since it was developed primarily in animals, we lack information on how general these patterns are across organisms. This is alarming if we are to understand how thermal tolerances are distributed globally, improve predictions of climate change, and mitigate effects. We approached this knowledge gap by compiling a geographically and taxonomically extensive database on plant heat and cold tolerances and used this dataset to test for thermal macrophysiological patterns and processes in plants. We found support for several expected patterns: Cold tolerances are more variable and exhibit steeper latitudinal clines and stronger relationships with local environmental temperatures than heat tolerances overall. Next, we disentangled the importance of local environments and evolutionary and biogeographic histories in generating these patterns. We found that all three processes have significantly contributed to variation in both heat and cold tolerances but that their relative importance differs. We also show that failure to simultaneously account for all three effects overestimates the importance of the included variable, challenging previous conclusions drawn from less comprehensive models. Our results are consistent with rare evolutionary innovations in cold acclimation ability structuring plant distributions across biomes. In contrast, plant heat tolerances vary mainly as a result of biogeographical processes and drift. Our results further highlight that all plants, particularly at mid-to-high latitudes and in their nonhardened state, will become increasingly vulnerable to ongoing climate change.


Assuntos
Termotolerância , Aclimatação , Adaptação Fisiológica , Altitude , Evolução Biológica , Mudança Climática , Temperatura Baixa , Ecossistema , Desenvolvimento Vegetal , Fenômenos Fisiológicos Vegetais , Plantas/classificação , Plantas/genética
12.
Proc Natl Acad Sci U S A ; 117(20): 10904-10910, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32366659

RESUMO

Darwin proposed two seemingly contradictory hypotheses regarding factors influencing the outcome of biological invasions. He initially posited that nonnative species closely related to native species would be more likely to successfully establish, because they might share adaptations to the local environment (preadaptation hypothesis). However, based on observations that the majority of naturalized plant species in the United States belonged to nonnative genera, he concluded that the lack of competitive exclusion would facilitate the establishment of alien invaders phylogenetically distinct from the native flora (competition-relatedness hypothesis). To date, no consensus has been reached regarding these opposing hypotheses. Here, following Darwin, we use the flora of the United States to examine patterns of taxonomic and phylogenetic relatedness between native and nonnative taxa across thousands of nested locations ranging in size and extent, from local to regional scales. We find that the probability of observing the signature of environmental filtering over that of competition increases with spatial scale. Further, native and nonnative species tended to be less related in warm, humid environments. Our work provides an empirical assessment of the role of observation scale and climate in biological invasions and demonstrates that Darwin's two opposing hypotheses need not be mutually exclusive.


Assuntos
Adaptação Fisiológica , Fenômenos Fisiológicos Vegetais , Seleção Genética , Evolução Biológica , Florestas , Modelos Biológicos , Filogenia , Desenvolvimento Vegetal , Plantas , Especificidade da Espécie , Estados Unidos
13.
Nat Commun ; 11(1): 2532, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32439842

RESUMO

Facilitation studies typically compare plants under differential stress levels with and without neighbors, while the density of neighbors has rarely been addressed. However, recent empirical studies indicate that facilitation may be density-dependent too and peak at intermediate neighbor densities. Here, we propose a conceptual model to incorporate density-dependence into theory about changes of plant-plant interactions under stress. To test our predictions, we combine an individual-based model incorporating both facilitative response and effect, with an experiment using salt stress and Arabidopsis thaliana. Theoretical and experimental results are strikingly consistent: (1) the intensity of facilitation peaks at intermediate density, and this peak shifts to higher densities with increasing stress; (2) this shift further modifies the balance between facilitation and competition such that the stress-gradient hypothesis applies only at high densities. Our model suggests that density-dependence must be considered for predicting plant-plant interactions under environmental change.


Assuntos
Ecossistema , Fenômenos Fisiológicos Vegetais , Estresse Fisiológico , Aclimatação , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Modelos Biológicos , Desenvolvimento Vegetal , Dinâmica Populacional
14.
Ecotoxicol Environ Saf ; 200: 110722, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32460047

RESUMO

Species Sensitivity Distributions (SSD) are widely used in environmental risk assessment to predict the concentration of a contaminant that is hazardous for 5% of species (HC5). They are based on monospecific bioassays conducted in the laboratory and thus do not directly take into account ecological interactions. This point, among others, is accounted for in environmental risk assessment through an assessment factor (AF) that is applied to compensate for the lack of environmental representativity. In this study, we aimed to assess the effects of interspecific competition on the responses towards isoproturon of plant species representative of a vegetated filter strip community, and to assess its impact on the derived SSD and HC5 values. To do so, we realized bioassays confronting six herbaceous species to a gradient of isoproturon exposure in presence and absence of a competitor. Several modelling approaches were applied to see how they affected the results, using different critical effect concentrations and investigating different ways to handle multiple endpoints in SSD. At the species level, there was a strong trend toward organisms being more sensitive to isoproturon in presence of a competitor than in its absence. At the community level, this trend was also observed in the SSDs and HC5 values were always lower in presence of a competitor (1.12-11.13 times lower, depending on the modelling approach). Our discussion questions the relevance of SSD and AF as currently applied in environmental risk assessment.


Assuntos
Fenômenos Fisiológicos Vegetais , Plantas/efeitos dos fármacos , Estresse Fisiológico , Bioensaio , Ecossistema , Compostos de Fenilureia/toxicidade , Medição de Risco
15.
Arch Insect Biochem Physiol ; 104(4): e21690, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32394499

RESUMO

The harlequin bug (HB), Murgantia histrionica, is a major pest of cabbage family plants throughout its range in the United States. RNA interference (RNAi) is a posttranscriptional gene silencing mechanism that is showing promise as a biopesticide due to the ability to target species-specific genes necessary for growth and/or survival with synthetic double-stranded RNA (dsRNA). In the present study, dsRNA stability assays revealed that nucleases present in the saliva of harlequin bugs did not rapidly degrade dsRNA. We tracked the movement and localization of radioactively labeled dsRNA in both mustard plant seedlings and harlequin bug nymphs that fed on treated host plants. Movement of 32 P-labeled-dsRNA from soil to plant and plant to insect was detected. The efficacy of RNAi in inducing mortality in harlequin bug adults and nymphs injected or fed with dsRNA targeting inhibitor of apoptosis (IAP), ATPase N2B (ATPase), serine/threonine-protein phosphatase PP1-ß catalytic subunit (PP1), signal recognition particle 54 kDa protein (SRP), and G protein-coupled receptor 161-like (GPCR) genes was evaluated. Injection of dsRNA targeting candidate genes into adults caused between 40% and 75% mortality and induced significant knockdown of target gene expression. Feeding dsRNA targeting the IAP gene to nymphs by plant-mediated and droplet feeding methods induced knockdown of the target gene and caused 40-55% mortality. These findings suggest that RNAi may be a viable approach for managing this pest.


Assuntos
Heterópteros/genética , Mostardeira/metabolismo , Interferência de RNA , Animais , Perfilação da Expressão Gênica , Heterópteros/crescimento & desenvolvimento , Heterópteros/metabolismo , Proteínas Inibidoras de Apoptose/genética , Controle de Insetos/métodos , Mostardeira/parasitologia , Ninfa/genética , Ninfa/metabolismo , Fenômenos Fisiológicos Vegetais , RNA de Cadeia Dupla , Ribonucleases , Saliva/enzimologia , Solo/química
16.
Integr Comp Biol ; 60(1): 89-97, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32386307

RESUMO

Comparative stress biology is inherently a systems biology approach with the goal of integrating the molecular, cellular, and physiological responses with fitness outcomes. In this way, the systems biology approach is expected to provide a holistic understanding of how different stressors result in different fitness outcomes, and how different individuals (or populations or species) respond to stressors differently. In this perceptive article, I focus on the use of multiple types of -omics data in stress biology. Targeting students and those researchers who are considering integrating -omics approaches in their comparative stress biology studies, I discuss the promise of the integration of these measures for furthering our holistic understanding of how organisms respond to different stressors. I also discuss the logistical and conceptual challenges encountered when working with -omics data and the current hurdles to fully utilize these data in studies of stress biology in non-model organisms.


Assuntos
Estresse Fisiológico , Biologia de Sistemas , Animais , Genômica , Lipidômica , Metabolômica , Fenômenos Fisiológicos Vegetais , Proteômica
17.
Ecol Lett ; 23(6): 1034-1048, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32281227

RESUMO

In this review, we examine the functional roles of microbial symbionts in plant tolerance to cold and freezing stresses. The impacts of symbionts on antioxidant activity, hormonal signaling and host osmotic balance are described, including the effects of the bacterial endosymbionts Burkholderia, Pseudomonas and Azospirillum on photosynthesis and the accumulation of carbohydrates such as trehalose and raffinose that improve cell osmotic regulation and plasma membrane integrity. The influence of root fungal endophytes and arbuscular mycorrhizal fungi on plant physiology at low temperatures, for example their effects on nutrient acquisition and the accumulation of indole-3-acetic acid and antioxidants in tissues, are also reviewed. Meta-analyses are presented showing that aspects of plant performance (shoot biomass, relative water content, sugar and proline concentrations and Fv /Fm ) are enhanced in symbiotic plants at low (-1 to 15 °C), but not at high (20-26 °C), temperatures. We discuss the implications of microbial symbionts for plant performance at low and sub-zero temperatures in the natural environment and propose future directions for research into the effects of symbionts on the cold and freezing tolerances of plants, concluding that further studies should routinely incorporate symbiotic microbes in their experimental designs.


Assuntos
Micorrizas , Biomassa , Fenômenos Fisiológicos Vegetais , Raízes de Plantas , Plantas , Simbiose
18.
Proc Natl Acad Sci U S A ; 117(15): 8532-8538, 2020 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-32229563

RESUMO

Understanding the driving mechanisms behind existing patterns of vegetation hydraulic traits and community trait diversity is critical for advancing predictions of the terrestrial carbon cycle because hydraulic traits affect both ecosystem and Earth system responses to changing water availability. Here, we leverage an extensive trait database and a long-term continental forest plot network to map changes in community trait distributions and quantify "trait velocities" (the rate of change in community-weighted traits) for different regions and different forest types across the United States from 2000 to the present. We show that diversity in hydraulic traits and photosynthetic characteristics is more related to local water availability than overall species diversity. Finally, we find evidence for coordinated shifts toward communities with more drought-tolerant traits driven by tree mortality, but the magnitude of responses differs depending on forest type. The hydraulic trait distribution maps provide a publicly available platform to fundamentally advance understanding of community trait change in response to climate change and predictive abilities of mechanistic vegetation models.


Assuntos
Biodiversidade , Mudança Climática , Ecossistema , Florestas , Fenômenos Fisiológicos Vegetais , Árvores/fisiologia , Água , Secas , Estresse Fisiológico
19.
Artigo em Inglês | MEDLINE | ID: mdl-32248039

RESUMO

In view of recent findings, it is still a matter of debate whether the composition of the phloem sap of higher plants is specific and based on a plasmodesmal selectivity filter for macromolecular transport, or whether simply related to size, abundance and half-life of the macromolecules within the phloem sap. A range of reports indicates specific function of phloem-mobile signaling molecules such as the florigen making it indispensable to discriminate specific macromolecules entering the phloem from others which cannot cross this selectivity filter. Nevertheless, several findings have discussed for a non-selective transport via plasmodesmata, or contamination of the phloem sap by degradation products coming from immature still developing young sieve elements undergoing differentiation. Here, we discuss several possibilities, and raise the question how selectivity of the phloem sap composition could be achieved thereby focusing on mobility and dynamics of sucrose transporter mRNA and proteins.


Assuntos
Floema , Fenômenos Fisiológicos Vegetais , Plasmodesmos , Floema/química , Floema/metabolismo , Plasmodesmos/metabolismo , Transdução de Sinais
20.
PLoS One ; 15(3): e0230097, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32168330

RESUMO

The relative importance of different community assembly mechanisms varies depending on the environment. According to the stress-dominance hypothesis (SDH), assembly mechanisms range from strong abiotic filtering to competition as the environment becomes more favourable. Most evidence for the SDH comes from studies in gradients of conditions (i.e. abiotic environmental factors that influence the functioning of organisms but are not consumed by them). However, we hypothesized that in resource gradients, competition increases as abiotic filtering becomes stronger. To test our hypothesis, we set up eight plots at different sites along an abiotic severity gradient in the Brazilian semi-arid region (BSAR). In each plot, we identified and measured each woody plant species found, and we recorded 11 functional traits of the main species, dividing the traits into alpha (competition effects) and beta (abiotic filtering effects). We investigated the presence of phylogenetic signal in the traits, the community phylogenetic and phenotypic patterns, and associated the variation in these patterns with the availability of water and soil nutrients. We found phylogenetic signal for most (91%) of the traits analysed. The phylogenetic patterns varied from clustered in stressful sites to random or overdispersed in favourable sites, and we concluded that these phylogenetic patterns were the result of historical processes influencing community assembly in different environments in the BSAR. In general, the phenotypic patterns varied from clustered at the most stressful end to random at less stressful sites. Our results show that in resource gradients, any restriction of the resource (hydric or edaphic) intensifies abiotic filtering and, at the same time, increases the competitive hierarchy among species. On the other hand, stochastic processes seem to have a stronger influence under more favourable abiotic conditions, where abiotic filtering and competition are weaker. Thus, we conclude that the SDH is not supported in resource gradients.


Assuntos
Biodiversidade , Ecossistema , Meio Ambiente , Fenômenos Fisiológicos Vegetais , Plantas/classificação , Estresse Fisiológico , Fenótipo , Filogenia
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