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1.
Int J Mol Sci ; 22(10)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34070033

RESUMO

Drought response in wheat is considered a highly complex process, since it is a multigenic trait; nevertheless, breeding programs are continuously searching for new wheat varieties with characteristics for drought tolerance. In a previous study, we demonstrated the effectiveness of a mutant known as RYNO3936 that could survive 14 days without water. In this study, we reveal another mutant known as BIG8-1 that can endure severe water deficit stress (21 days without water) with superior drought response characteristics. Phenotypically, the mutant plants had broader leaves, including a densely packed fibrous root architecture that was not visible in the WT parent plants. During mild (day 7) drought stress, the mutant could maintain its relative water content, chlorophyll content, maximum quantum yield of PSII (Fv/Fm) and stomatal conductance, with no phenotypic symptoms such as wilting or senescence despite a decrease in soil moisture content. It was only during moderate (day 14) and severe (day 21) water deficit stress that a decline in those variables was evident. Furthermore, the mutant plants also displayed a unique preservation of metabolic activity, which was confirmed by assessing the accumulation of free amino acids and increase of antioxidative enzymes (peroxidases and glutathione S-transferase). Proteome reshuffling was also observed, allowing slow degradation of essential proteins such as RuBisCO during water deficit stress. The LC-MS/MS data revealed a high abundance of proteins involved in energy and photosynthesis under well-watered conditions, particularly Serpin-Z2A and Z2B, SGT1 and Calnexin-like protein. However, after 21 days of water stress, the mutants expressed ABC transporter permeases and xylanase inhibitor protein, which are involved in the transport of amino acids and protecting cells, respectively. This study characterizes a new mutant BIG8-1 with drought-tolerant characteristics suited for breeding programs.


Assuntos
Secas , Mutação , Triticum/genética , Triticum/fisiologia , Aclimatação/genética , Aminoácidos/metabolismo , Antioxidantes/metabolismo , Clorofila/metabolismo , Metanossulfonato de Etila/toxicidade , Mutagênicos/toxicidade , Fenótipo , Complexo de Proteína do Fotossistema II/metabolismo , Melhoramento Vegetal , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Proteoma/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Estresse Fisiológico/genética , Triticum/efeitos dos fármacos , Água/metabolismo
2.
BMC Plant Biol ; 21(1): 227, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34020594

RESUMO

BACKGROUND: Root hypoxia has detrimental effects on physiological processes and growth in most plants. The effects of hypoxia can be partly alleviated by ethylene. However, the tolerance mechanisms contributing to the ethylene-mediated hypoxia tolerance in plants remain poorly understood. RESULTS: In this study, we examined the effects of root hypoxia and exogenous ethylene treatments on leaf gas exchange, root hydraulic conductance, and the expression levels of several aquaporins of the plasma membrane intrinsic protein group (PIP) in trembling aspen (Populus tremuloides) seedlings. Ethylene enhanced net photosynthetic rates, transpiration rates, and root hydraulic conductance in hypoxic plants. Of the two subgroups of PIPs (PIP1 and PIP2), the protein abundance of PIP2s and the transcript abundance of PIP2;4 and PIP2;5 were higher in ethylene-treated trembling aspen roots compared with non-treated roots under hypoxia. The increases in the expression levels of these aquaporins could potentially facilitate root water transport. The enhanced root water transport by ethylene was likely responsible for the increase in leaf gas exchange of the hypoxic plants. CONCLUSIONS: Exogenous ethylene enhanced root water transport and the expression levels of PIP2;4 and PIP2;5 in hypoxic roots of trembling aspen. The results suggest that ethylene facilitates the aquaporin-mediated water transport in plants exposed to root hypoxia.


Assuntos
Aquaporinas/genética , Etilenos/farmacologia , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/genética , Populus/metabolismo , Água/metabolismo , Aquaporinas/metabolismo , Transporte Biológico , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Populus/efeitos dos fármacos , Populus/genética
3.
Anal Chim Acta ; 1163: 338441, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34024416

RESUMO

This paper reports a microfluidic lab-on-chip for dynamic particle sizing and real time individual cell membrane permeability measurements. To achieve this, the device measures the impedance change of individual cells or particles at up to ten time points after mixing with different media, e.g. dimethyl sulfoxide or DI water, from separate inlets. These measurements are enabled by ten gold electrode pairs spread across a 20 mm long microchannel. The device measures impedance values within 0.26 s after mixing with other media, has a detection throughput of 150 samples/second, measures impedance values at all ten electrodes at this rate, and allows tracking of individual cell volume changes caused by cell osmosis in anisosmotic fluids over a 1.3 s postmixing timespan, facilitating accurate individual cell estimates of water permeability. The design and testing were performed using yeast cells (Saccharomyces cerevisiae). The relationship between volume and impedance in both polystyrene calibration beads as well as the volume-osmolality relationship in yeast were demonstrated. Moreover, we present the first noninvasive and non-optically-based water permeability measurements in individual cells.


Assuntos
Microfluídica , Água , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular , Impedância Elétrica , Permeabilidade , Água/metabolismo
4.
Int J Mol Sci ; 22(9)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946369

RESUMO

Activity-dependent fluid secretion is the most important physiological function of salivary glands and is regulated via muscarinic receptor signaling. Lipid rafts are important for G-protein coupled receptor (GPCR) signaling and ion channels in plasma membranes. However, it is not well understood whether lipid raft disruption affects all membrane events or only specific functions in muscarinic receptor-mediated water secretion in salivary gland cells. We investigated the effects of lipid raft disruption on the major membrane events of muscarinic transcellular water movement in human salivary gland (HSG) cells. We found that incubation with methyl-ß-cyclodextrin (MßCD), which depletes lipid rafts, inhibited muscarinic receptor-mediated Ca2+ signaling in HSG cells and isolated mouse submandibular acinar cells. However, MßCD did not inhibit a Ca2+ increase induced by thapsigargin, which activates store-operated Ca2+ entry (SOCE). Interestingly, MßCD increased the activity of the large-conductance Ca2+-activated K+ channel (BK channel). Finally, we found that MßCD did not directly affect the translocation of aquaporin-5 (AQP5) into the plasma membrane. Our results suggest that lipid rafts maintain muscarinic Ca2+ signaling at the receptor level without directly affecting the activation of SOCE induced by intracellular Ca2+ pool depletion or the translocation of AQP5 into the plasma membrane.


Assuntos
Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Microdomínios da Membrana/metabolismo , Receptores Muscarínicos/metabolismo , Glândulas Salivares/metabolismo , Linhagem Celular , Humanos , Glândulas Salivares/citologia , Água/metabolismo
5.
Food Microbiol ; 98: 103783, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33875211

RESUMO

Factors that control pathogen survival in low water activity foods are not well understood and vary greatly from food to food. A literature search was performed to locate data on the survival of foodborne pathogens in low-water activity (<0.70) foods held at temperatures <37 °C. Data were extracted from 67 publications and simple linear regression models were fit to each data set to estimate log linear rates of change. Multiple linear stepwise regression models for factors influencing survival rate were developed. Subset regression modeling gave relatively low adjusted R2 values of 0.33, 0.37, and 0.48 for Salmonella, E. coli and L. monocytogenes respectively, but all subset models were highly significant (p < 1.0e-9). Subset regression models showed that Salmonella survival was significantly (p < 0.05) influenced by temperature, serovar and strain type, water activity, inoculum preparation method, and inoculation method. E. coli survival was significantly influenced by temperature, water activity, and inoculum preparation. L. monocytogenes survival was significantly influenced by temperature, serovar and strain type, and inoculum preparation method. While many factors were highly significant (p < 0.001), the high degrees of variability show that there is still much to learn about the factors which govern pathogen survival in low water activity foods.


Assuntos
Escherichia coli O157/crescimento & desenvolvimento , Contaminação de Alimentos/análise , Listeria monocytogenes/crescimento & desenvolvimento , Viabilidade Microbiana , Salmonella/crescimento & desenvolvimento , Água/análise , Escherichia coli O157/metabolismo , Análise de Alimentos , Microbiologia de Alimentos , Listeria monocytogenes/metabolismo , Modelos Biológicos , Salmonella/metabolismo , Temperatura , Água/metabolismo
6.
Nature ; 592(7852): 65-69, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33790442

RESUMO

Year-to-year changes in carbon uptake by terrestrial ecosystems have an essential role in determining atmospheric carbon dioxide concentrations1. It remains uncertain to what extent temperature and water availability can explain these variations at the global scale2-5. Here we use factorial climate model simulations6 and show that variability in soil moisture drives 90 per cent of the inter-annual variability in global land carbon uptake, mainly through its impact on photosynthesis. We find that most of this ecosystem response occurs indirectly as soil moisture-atmosphere feedback amplifies temperature and humidity anomalies and enhances the direct effects of soil water stress. The strength of this feedback mechanism explains why coupled climate models indicate that soil moisture has a dominant role4, which is not readily apparent from land surface model simulations and observational analyses2,5. These findings highlight the need to account for feedback between soil and atmospheric dryness when estimating the response of the carbon cycle to climatic change globally5,7, as well as when conducting field-scale investigations of the response of the ecosystem to droughts8,9. Our results show that most of the global variability in modelled land carbon uptake is driven by temperature and vapour pressure deficit effects that are controlled by soil moisture.


Assuntos
Atmosfera/química , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Ecossistema , Retroalimentação , Solo/química , Água/análise , Dióxido de Carbono/análise , Umidade , Fotossíntese , Temperatura , Água/metabolismo
7.
Int J Mol Sci ; 22(6)2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33802151

RESUMO

Water-deficit stresses such as drought and salinity are the most important factors limiting crop productivity. Hence, understanding the plant responses to these stresses is key for the improvement of their tolerance and yield. In this study M. truncatula plants were subjected to 250 mM NaCl as well as reduced irrigation (No-W) and 250 g/L polyethylene glycol (PEG)-6000 to induce salinity and drought stress, respectively, provoking a drop to -1.7 MPa in leaf water potential. The whole plant physiology and metabolism was explored by characterizing the stress responses at root, phloem sap and leaf organ level. PEG treatment led to some typical responses of plants to drought stress, but in addition to PEG uptake, an important impairment of nutrient uptake and a different regulation of carbon metabolism could be observed compared to No-W plants. No-W plants showed an important redistribution of antioxidants and assimilates to the root tissue, with a distinctive increase in root proline degradation and alkaline invertase activity. On the contrary, salinity provoked an increase in leaf starch and isocitrate dehydrogenase activity, suggesting key roles in the plant response to this stress. Overall, results suggest higher protection of salt-stressed shoots and non-irrigated roots through different mechanisms, including the regulation of proline and carbon metabolism, while discarding PEG as safe mimicker of drought. This raises the need to understand the effect at the whole plant level of the different strategies employed to apply water-deficit stress.


Assuntos
Regulação da Expressão Gênica de Plantas , Medicago truncatula/metabolismo , Pressão Osmótica , Folhas de Planta/metabolismo , Água/metabolismo , Desidratação
8.
Nat Commun ; 12(1): 2310, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33875648

RESUMO

Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change.


Assuntos
Carboidratos/análise , Secas , Florestas , Estações do Ano , Árvores/metabolismo , Água/metabolismo , Bolívia , Brasil , Metabolismo dos Carboidratos , Mudança Climática , Geografia , Peru , Folhas de Planta/metabolismo , Açúcares/metabolismo , Árvores/classificação , Clima Tropical
9.
Nat Commun ; 12(1): 2320, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33875659

RESUMO

Lignin is a complex polymer deposited in the cell wall of specialised plant cells, where it provides essential cellular functions. Plants coordinate timing, location, abundance and composition of lignin deposition in response to endogenous and exogenous cues. In roots, a fine band of lignin, the Casparian strip encircles endodermal cells. This forms an extracellular barrier to solutes and water and plays a critical role in maintaining nutrient homeostasis. A signalling pathway senses the integrity of this diffusion barrier and can induce over-lignification to compensate for barrier defects. Here, we report that activation of this endodermal sensing mechanism triggers a transcriptional reprogramming strongly inducing the phenylpropanoid pathway and immune signaling. This leads to deposition of compensatory lignin that is chemically distinct from Casparian strip lignin. We also report that a complete loss of endodermal lignification drastically impacts mineral nutrients homeostasis and plant growth.


Assuntos
Arabidopsis/metabolismo , Parede Celular/metabolismo , Lignina/metabolismo , Raízes de Plantas/metabolismo , Água/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Membrana Celular/metabolismo , Parede Celular/genética , Difusão , Lignina/química , Microscopia de Fluorescência/métodos , Mutação , Fenilpropionatos/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , RNA-Seq/métodos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Xilema/genética , Xilema/metabolismo
10.
Int J Mol Sci ; 22(6)2021 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-33805821

RESUMO

Drought is the most serious abiotic stress, which significantly reduces crop productivity. The phytohormone ABA plays a pivotal role in regulating stomatal closing upon drought stress. Here, we characterized the physiological function of AtBBD1, which has bifunctional nuclease activity, on drought stress. We found that AtBBD1 localized to the nucleus and cytoplasm, and was expressed strongly in trichomes and stomatal guard cells of leaves, based on promoter:GUS constructs. Expression analyses revealed that AtBBD1 and AtBBD2 are induced early and strongly by ABA and drought, and that AtBBD1 is also strongly responsive to JA. We then compared phenotypes of two AtBBD1-overexpression lines (AtBBD1-OX), single knockout atbbd1, and double knockout atbbd1/atbbd2 plants under drought conditions. We did not observe any phenotypic difference among them under normal growth conditions, while OX lines had greatly enhanced drought tolerance, lower transpirational water loss, and higher proline content than the WT and KOs. Moreover, by measuring seed germination rate and the stomatal aperture after ABA treatment, we found that AtBBD1-OX and atbbd1 plants showed significantly higher and lower ABA-sensitivity, respectively, than the WT. RNA sequencing analysis of AtBBD1-OX and atbbd1 plants under PEG-induced drought stress showed that overexpression of AtBBD1 enhances the expression of key regulatory genes in the ABA-mediated drought signaling cascade, particularly by inducing genes related to ABA biosynthesis, downstream transcription factors, and other regulatory proteins, conferring AtBBD1-OXs with drought tolerance. Taken together, we suggest that AtBBD1 functions as a novel positive regulator of drought responses by enhancing the expression of ABA- and drought stress-responsive genes as well as by increasing proline content.


Assuntos
Ácido Abscísico/metabolismo , Adaptação Fisiológica/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Endonucleases/genética , Regulação da Expressão Gênica de Plantas , Ácido Abscísico/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/enzimologia , Proteínas de Arabidopsis/agonistas , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Ciclopentanos/metabolismo , Ciclopentanos/farmacologia , Citoplasma/metabolismo , Secas , Endonucleases/antagonistas & inibidores , Endonucleases/metabolismo , Isoenzimas/antagonistas & inibidores , Isoenzimas/genética , Isoenzimas/metabolismo , Oxilipinas/metabolismo , Oxilipinas/farmacologia , Células Vegetais/efeitos dos fármacos , Células Vegetais/enzimologia , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/enzimologia , Folhas de Planta/genética , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/enzimologia , Estômatos de Plantas/genética , Plantas Geneticamente Modificadas , Prolina/metabolismo , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Água/metabolismo
11.
AAPS PharmSciTech ; 22(4): 139, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33880664

RESUMO

Chemical enhancers (CEs) decreased the barrier of the stratum corneum (SC) to enhance drug permeation. This was a "dynamic" behavior, which involved three processes including passing in, acting on, and passing out of the SC. However, compared with mature "static" researches about acting on the SC, the other two processes were poorly understood. This work aimed to probe the dynamic behavior of CEs and modulate it for satisfactory effectiveness. The investigating method of CEs' dynamic behavior was established to obtain the rate of CEs passing in and out of the SC. An analysis attribution was conducted to obtain the possible reasons for the quite different dynamic behavior of CEs based on log P, solubility parameter, and minimum binging energy. It demonstrated the rate of CEs passing in and out of the SC was dependent on CE affinity with the SC and the interaction between CEs and the SC, respectively. The relevance between CEs' dynamic behavior and the extent of decreasing SC barrier was confirmed by transepidermal water loss (TEWL). The higher rate of CE passing in the SC and a lower rate of passing out of the SC may contribute to an increased concentration of CEs in the SC, leading to a stronger ability to decrease the SC barrier. More importantly, two biodegradable CEs (Leu-Dod and Ser-Dod) of dodecanol were synthesized and achieved a modulation of its dynamic behavior to obtain more satisfactory effectiveness of enhancing drug permeation. This work was meaningful for the guidance of rationally promoting CEs' effectiveness from a dynamic perspective, which was an unprecedented attempt in this field.


Assuntos
Absorção Cutânea , Pele/metabolismo , Materiais Biocompatíveis , Epiderme/metabolismo , Humanos , Solubilidade , Água/metabolismo
12.
Molecules ; 26(8)2021 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-33921620

RESUMO

The geographical origin of honey affects its composition, which is of key importance for the health-promoting properties and safety of the product. European regulations clearly define the physicochemical requirements for honey that determine the microbiological quality. On the other hand, legislation abolishes microbiological criteria. In the study 40 honey samples originating from two different climatic zones were analyzed. The water content, pH, water activity analysis and the microbiological quality of honey samples have been tested using the reference plate method (total viable count, yeast and molds, lactic acid bacteria, Bacillus spp.). The cluster classification showed that total viable count of bacteria could be used as a measure alternative to the count of Bacillus spp. and 70% of honeys from the tropical climate zone had different microbiological quality than honeys from the temperate climate zone but still under the level 3.0 log cfu/g. The study has revealed that geographical origin of honey may significantly affect the quality and safety of honey. It was considered that water content can be the most informative and handy marker of the microbiological quality of honeys. Analysis of lactic acid bacteria showed temperate climate zone honeys as a source of beneficial bacteria in the diet.


Assuntos
Análise por Conglomerados , Mel/análise , Lactobacillales , Probióticos , Água/metabolismo
13.
Physiol Plant ; 172(2): 1089-1105, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33826759

RESUMO

Drought stress alters gene expression and causes cellular damage in crop plants. Drought inhibits photosynthesis by reducing the content and the activity of the photosynthetic carbon reduction cycle, ultimately decreasing the crop yield. The role of aquaporins (AQP) in improving the growth and adaptation of crop plants under drought stress is of importance. AQP form channels and control water transport in and out of the cells and are associated with drought tolerance mechanisms. The current review addresses: (1) the evolution of AQPs in plants, (2) the classification of plant AQPs, (3) the role of AQPs in drought alleviation in crop plants, and (4) the phytohormone crosstalk with AQPs in crops exposed to drought stress.


Assuntos
Aquaporinas , Secas , Aquaporinas/genética , Aquaporinas/metabolismo , Fotossíntese , Reguladores de Crescimento de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/metabolismo , Estresse Fisiológico , Água/metabolismo
14.
Int J Mol Sci ; 22(7)2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33805500

RESUMO

In this book, the papers published in the second issue, "Ion and Molecule Transport in Membrane Systems 2 [...].


Assuntos
Membrana Celular/metabolismo , Íons/metabolismo , Membranas Artificiais , Animais , Transporte Biológico , Água/metabolismo
15.
Ecotoxicol Environ Saf ; 215: 112101, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33765593

RESUMO

Rare earth elements (REEs) are gaining growing attention in environmental and ecotoxicological studies due to their economic relevance, wide range of applications and increasing environmental concentrations. Among REEs, special consideration should be given to Gadolinium (Gd), whose wide exploitation as a magnetic resonance imaging (MRI) contrast agent is enhancing the risk of its occurrence in aquatic environments and impacts on aquatic organisms. A promising approach for water decontamination from REEs is sorption, namely through the use of macroalgae and in particular Ulva lactuca that already proved to be an efficient biosorbent for several chemical elements. Therefore, the present study aimed to evaluate the toxicity of Gd, comparing the biochemical effects induced by this element in the presence or absence of algae. Using the bivalve species Mytilus galloprovincialis, Gd toxicity was evaluated by assessing changes on mussels' metabolic capacity and oxidative status. Results clearly showed the toxicity of Gd but further revealed the capacity of U. lactuca to prevent injuries to M. galloprovincialis, mainly reducing the levels of Gd in water and thus the bioaccumulation and toxicity of this element by the mussels. The results will advance the state of the art not only regarding the effects of REEs but also with regard to the role of algae in accumulation of metals and protection of aquatic organisms, generating new insights on water safety towards aquatic wildlife and highlighting the possibility for resources recovery.


Assuntos
Gadolínio/metabolismo , Mytilus/metabolismo , Ulva/fisiologia , Poluentes Químicos da Água/metabolismo , Animais , Animais Selvagens/metabolismo , Ecotoxicologia , Metais Terras Raras , Mytilus/efeitos dos fármacos , Oxirredução , Alga Marinha/metabolismo , Ulva/metabolismo , Água/metabolismo , Poluentes Químicos da Água/toxicidade
16.
Plant Physiol Biochem ; 162: 27-35, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33662869

RESUMO

Aquaporins (AQPs) involved in water and small molecule transport respond to environmental stress, while it is not clear how arbuscular mycorrhizal fungi (AMF) regulate AQP expression. Here, we investigated the change in leaf water potential and expression level of four tonoplast intrinsic proteins (TIPs), six plasma membrane intrinsic proteins (PIPs), and four nodin-26 like intrinsic proteins (NIPs) genes in trifoliate orange (Poncirus trifoliata) inoculated with Funneliformis mosseae under well-watered (WW), salt stress (SS), and waterlogging stress (WS). Root AMF colonization and soil hyphal length collectively were reduced by SS and WS. Under WW, inoculation with AMF gave diverse responses of AQPs: six AQPs up-regulated, three AQPs down-regulated, and five AQPs did not change. Such up-regulation of more AQPs under mycorrhization and WW partly accelerated water absorption, thereby, maintaining higher leaf water potential. However, under SS, all the fourteen AQPs were dramatically induced by AMF inoculation, which improved water permeability of membranes and stimulated water transport of the host. Under WS, AMF colonization almost did not induce or even down-regulated these AQPs expressions with three exceptions (PtTIP2;2, PtPIP1;1, and PtNIP1;2), thus, no change in leaf water potential. As a result, mycorrhizal plants under flooding may have an escape mechanism to reduce water absorption. It is concluded that AMF had different strategies in response to environmental stresses (e.g. SS and WS) by regulating leaf AQP expression in the host (e.g. trifoliate orange).


Assuntos
Aquaporinas , Micorrizas , Poncirus , Fungos , Micorrizas/metabolismo , Folhas de Planta/metabolismo , Poncirus/metabolismo , Estresse Salino , Água/metabolismo
17.
Plant Physiol Biochem ; 162: 161-170, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33684775

RESUMO

Drought stress poses a severe threat to grain yield in rice. Our previous report demonstrated the role of OsJAZ9 in potassium homeostasis by modulating Jasmonic Acid (JA) signalling. While both potassium (K) and JA are known to have an important role in drought stress response, JA's repressor, i.e., JAZs' role in drought stress, remains elusive. Here we report that OsJAZ9 plays a critical role in rice water-deficit stress tolerance via influencing JA and ABA signalling. Overexpression of OsJAZ9 led to the enhanced ABA and JA levels. Our data further revealed that exogenous JA application antagonises the ABA-mediated inhibition of seed germination. Further, OsJAZ9 overexpression reduces leaf width and stomata density, leading to lower leaf transpiration rates than WT. This reduced transpiration and higher K content as osmoticum improved the water-deficit stress tolerance in OsJAZ9 overexpression lines. On the contrary, OsJAZ9 RNAi lines displayed enhanced sensitivity towards water-deficit stress. Our data provide new insights on the role of JA signalling repressors in rice response to water-deficit stress.


Assuntos
Oryza , Ácido Abscísico , Secas , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/metabolismo , Estresse Fisiológico , Água/metabolismo
18.
Nat Plants ; 7(3): 317-326, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33649595

RESUMO

The widely used theory for gas exchange proposed by von Caemmerer and Farquhar (vCF) integrates molar fluxes, mole fraction gradients and ternary effects but does not account for cuticular fluxes, for separation of the leaf surface conditions or for ternary effects within the boundary layer. The magnitude of cuticular conductance to water (gcw) is a key factor for determining plant survival in drought but is difficult to measure and often neglected in routine gas exchange studies. The vCF ternary effect is applied to the total flux without the recognition of different pathways that are affected by it. These simplifications lead to errors in estimations of stomatal conductance, intercellular carbon dioxide concentration (Ci) and other gas exchange parameters. The theory presented here is a more precise physical approach to the electrical resistance analogy for gas exchange, resulting in a more accurate calculation of gas exchange parameters. Additionally, we extend our theory, using physiological concepts, to create a model that allows us to calculate cuticular conductance to water.


Assuntos
Folhas de Planta/metabolismo , Transpiração Vegetal , Plantas/metabolismo , Dióxido de Carbono/metabolismo , Modelos Biológicos , Temperatura , Água/metabolismo
19.
Am J Physiol Heart Circ Physiol ; 320(4): H1724-H1737, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33710913

RESUMO

The surface of vascular endothelial cells (ECs) is covered by a protective negatively charged layer known as the endothelial glycocalyx. Herein, we hypothesized its transport barrier and mechanosensory role in transmural water flux and low-density lipoprotein (LDL) transport in an isolated rat abdominal aorta perfused under 85 mmHg and 20 dyn/cm2 ex vivo. The endothelial glycocalyx was digested by hyaluronidase (HAase) from bovine tests. Water infiltration velocity (Vw) was measured by a graduated pipette. LDL coverage and mean maximum infiltration distance (MMID) in the vessel wall were quantified by confocal laser scanning microscopy. EC apoptosis was determined by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) technique, and leaky junction rates were evaluated by electron microscopy. The results showed that a 42% degradation of the endothelial glycocalyx by HAase treatment increased Vw, LDL coverage, and MMID. Shear stress increased Vw, which cannot be inhibited by HAase treatment. Four hour-shear application increased about fourfolds of LDL coverage, whereas exerted no significant effects on its MMID, EC apoptosis, and the leaky junctions. On the contrary, 24-h shear exposure has no significant effects on LDL coverage, whereas increased 2.74-folds of MMID and about 53% of EC apoptotic rates that could be inhibited by HAase treatment. These results suggest endothelial glycocalyx acts as a transport barrier by decreasing water and LDL transport, as well as a mechanosensor of shear to regulate EC apoptosis, thus affecting leaky junctions and regulating LDL transport into the vessel wall.NEW & NOTEWORTHY A 42% degradation of the endothelial glycocalyx by hyaluronidase of the isolated rat abdominal aorta facilitated water and LDL transport across the vessel wall, suggesting endothelial glycocalyx as a transport barrier. A 24-h shear exposure increased LDL mean maximum infiltration distance, and enhanced EC apoptosis, which could be both inhibited by hyaluronidase treatment, suggesting endothelial glycocalyx may also act as a mechanosensor of shear to regulate EC apoptosis, thus affecting leaky junctions and regulating LDL transport.


Assuntos
Aorta Abdominal/metabolismo , Células Endoteliais/metabolismo , Glicocálix/metabolismo , Lipoproteínas LDL/metabolismo , Água/metabolismo , Animais , Aorta Abdominal/ultraestrutura , Apoptose , Transporte Biológico , Células Endoteliais/ultraestrutura , Glicocálix/ultraestrutura , Hialuronoglucosaminidase/metabolismo , Técnicas In Vitro , Masculino , Mecanotransdução Celular , Permeabilidade , Ratos Sprague-Dawley , Fluxo Sanguíneo Regional , Estresse Mecânico
20.
Nat Commun ; 12(1): 1952, 2021 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-33782393

RESUMO

The non-protein amino acid γ-aminobutyric acid (GABA) has been proposed to be an ancient messenger for cellular communication conserved across biological kingdoms. GABA has well-defined signalling roles in animals; however, whilst GABA accumulates in plants under stress it has not been determined if, how, where and when GABA acts as an endogenous plant signalling molecule. Here, we establish endogenous GABA as a bona fide plant signal, acting via a mechanism not found in animals. Using Arabidopsis thaliana, we show guard cell GABA production is necessary and sufficient to reduce stomatal opening and transpirational water loss, which improves water use efficiency and drought tolerance, via negative regulation of a stomatal guard cell tonoplast-localised anion transporter. We find GABA modulation of stomata occurs in multiple plants, including dicot and monocot crops. This study highlights a role for GABA metabolism in fine tuning physiology and opens alternative avenues for improving plant stress resilience.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Canais de Cloreto/genética , Glutamato Descarboxilase/genética , Estômatos de Plantas/metabolismo , Transpiração Vegetal/genética , Água/metabolismo , Ácido gama-Aminobutírico/metabolismo , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Adaptação Fisiológica/genética , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Canais de Cloreto/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Glutamato Descarboxilase/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Hordeum/genética , Hordeum/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/genética , Transpiração Vegetal/efeitos dos fármacos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Soja/genética , Soja/metabolismo , Estresse Fisiológico , Tabaco/genética , Tabaco/metabolismo , Vicia faba/genética , Vicia faba/metabolismo
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