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1.
Photochem Photobiol Sci ; 19(1): 88-98, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31904040

RESUMO

Stomatal pores, which are surrounded by pairs of guard cells in the plant epidermis, regulate gas exchange between plants and the atmosphere, thereby controlling photosynthesis and transpiration. Blue light works as a signal to guard cells, to induce intracellular signaling and open stomata. Blue light receptor phototropins (phots) are activated by blue light; phot-mediated signals promote plasma membrane (PM) H+-ATPase activity via C-terminal Thr phosphorylation, serving as the driving force for stomatal opening in guard cells. However, the details of this signaling process are not fully understood. In this study, through an in vitro screening of phot-interacting protein kinases, we obtained the CBC1 and CBC2 that had been reported as signal transducers in stomatal opening. Promoter activities of CBC1 and CBC2 indicated that both genes were expressed in guard cells. Single and double knockout mutants of CBC1 and CBC2 showed no lesions in the context of phot-mediated phototropism, chloroplast movement, or leaf flattening. In contrast, the cbc1cbc2 double mutant showed larger stomatal opening under both dark and blue light conditions. Interestingly, the level of phosphorylation of C-terminal Thr of PM H+-ATPase was higher in double mutant guard cells. The larger stomatal openings of the double mutant were effectively suppressed by the phytohormone abscisic acid (ABA). CBC1 and CBC2 interacted with BLUS1 and PM H+-ATPase in vitro. From these results, we conclude that CBC1 and CBC2 act as negative regulators of stomatal opening, probably via inhibition of PM H+-ATPase activity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Membrana Celular/enzimologia , Estômatos de Plantas/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Fosforilação
2.
Trends Plant Sci ; 25(3): 220-223, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31932167

RESUMO

Although reactive oxygen species (ROS) function in guard cell signaling has been demonstrated, the control of ROS homeostasis remains elusive. Recent findings point to multiple mechanisms controlling ROS levels in guard cells. These mechanisms require secondary metabolism and autophagy, providing the guard cells with a degree of plasticity during stomatal movements.


Assuntos
Estômatos de Plantas , Transdução de Sinais , Ácido Abscísico , Homeostase , Espécies Reativas de Oxigênio
3.
Plant Mol Biol ; 102(1-2): 89-107, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31768809

RESUMO

KEY MESSAGE: OsPUB67, a U-box E3 ubiquitin ligase, may interact with two drought tolerance negative regulators (OsRZFP34 and OsDIS1) and improve drought tolerance by enhancing the reactive oxygen scavenging ability and stomatal closure. E3 ubiquitin ligases are major components of the ubiquitination cascade and contribute to the biotic and abiotic stress response in plants. In the present study, we show that a rice drought responsive gene, OsPUB67, encoding the U-box E3 ubiquitin ligase was significantly induced by drought, salt, cold, JA, and ABA, and was expressed in nuclei, cytoplasm, and membrane systems. This distribution of expression suggests a significant role for OsPUB67 in a wide range of biological processes and abiotic stress response. Over-expression of OsPUB67 improved drought stress tolerance by enhancing the reactive oxygen scavenging ability and stomatal closure. Bimolecular fluorescence complementation assays revealed that a few E2s interacted with OsPUB67 with unique functional implications in different cell components. Further evidence showed that several E3 ubiquitin ligases interacted with OsPUB67, especially OsRZFP34 and OsDIS1, which are negative regulators of drought tolerance. This interaction on the stomata implied OsPUB67 might function as a heterodimeric ubiquitination complex in response to drought stress. Comprehensive transcriptome analysis revealed OsPUB67 participated in regulating genes involved in the abiotic stress response and transcriptional regulation in an ABA-dependent manner. Our findings revealed OsPUB67 mediated a multilayered complex drought stress tolerance mechanism.


Assuntos
Secas , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico/fisiologia , Ubiquitina-Proteína Ligases/metabolismo , Aclimatação/genética , Aclimatação/fisiologia , Sequência de Aminoácidos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Oryza/genética , Fenótipo , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Estômatos de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Plântula , Alinhamento de Sequência , Análise de Sequência de Proteína , Cloreto de Sódio/farmacologia , Estresse Fisiológico/genética , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/isolamento & purificação , Ubiquitinação
4.
Sci Total Environ ; 699: 134402, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31683210

RESUMO

Ground-level ozone (O3) is an important phytotoxic air pollutant in China. In order to compare the sensitivity of common poplar clones to O3 in China and explore the possible mechanism, five poplar clones, clone DQ (Populus cathayana), clone 84 K (P. alba × P. glandulosa), clone WQ156 (P. deltoids × P. cathayana), clone 546 (P. deltoides cv. '55/56' × P. deltoides cv. 'Imperial') and clone 107 (P. euramericana cv. '74/76') were exposed to four O3 treatments. According to the date of the initial visible O3 symptom and the slopes of O3 exposure-response relationships with the relative light-saturated rate of CO2 assimilation, we found that clone DQ and clone 546 were the most sensitive to O3, clone 84 K and clone WQ156 were the less sensitive, and clone 107 was the most tolerant, which could provide a basis to select O3 tolerant clones for poplar planting at areas with serious O3 pollution. Elevated O3 significantly reduced photosynthetic parameters, total phenols content, potential antioxidant capacity, leaf mass per area and biomass of five poplar clones, and there were significant interactions between O3 and clones for most photosynthetic parameters. Elevated O3 also significantly increased malondialdehyde content and total ascorbate content. The responses of total antioxidant capacity for poplar clones to elevated O3 were different, as indicated by the increase for clone 107 and reduction for other clones under elevated O3 treatment. Our results on the sensitivity of different poplar clones to O3 are not related to leaf stomatal conductance, leaf constitutive antioxidant levels or leaf morphology of plant grown in clean air. The possible reason is little difference in leaf traits among clones within close species, suggesting that more properties of plants should be considered for exploring the sensitivity mechanism of close species, such as mesophyll conductance, antioxidant enzyme activity and apoplastic antioxidants.


Assuntos
Poluentes Atmosféricos/toxicidade , Ozônio/toxicidade , Estômatos de Plantas/fisiologia , Populus/fisiologia , Antioxidantes , China , Clorofila/metabolismo , Fotossíntese , Folhas de Planta
5.
Plant Sci ; 290: 110245, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779890

RESUMO

ABA is important for plant growth and development; however, it also inhibits photosynthesis by regulating the stomatal aperture and ribulose-1,5-bisphosphate carboxylase/oxygenase activity. Noteworthy, this negative effect can be alleviated by antioxidants including ascorbic acid (AsA) and catalase (CAT), but the underlying mechanism remains unclear. Two rice cultivars, Zhefu802 (recurrent parent) and its near-isogenic line, fgl were selected and planted in a greenhouse with 30/24 °C (day/night) under natural sunlight conditions. Compared to fgl, Zhefu802 had significantly lower net photosynthetic rate (PN) and stomatal conductance (Cond) as well as significantly higher ABA and H2O2 contents. However, AsA and CAT increased PN, Cond, and stomatal aperture, which decreased H2O2 and malondialdehyde (MDA) levels. In this process, AsA and CAT significantly increased the ribulose-1,5-bisphosphate carboxylase activity, while they strongly decreased the ribulose-1,5-bisphosphate oxygenase activity, and finally caused an obvious decrease in the ratio of photorespiration (Pr) to PN. Additionally, AsA and CAT significantly increased the expression levels of RbcS and RbcL genes of leaves, while H2O2 significantly decreased them, especially the RbcS gene. In summary, the removal of H2O2 by AsA and CAT can improve the leaf photosynthesis by alleviating the inhibition on the stomatal conductance and ribulose-1,5-bisphosphate carboxylase capacity caused by ABA.


Assuntos
Antioxidantes/metabolismo , Oryza/fisiologia , Fotossíntese , Estômatos de Plantas/fisiologia , Ribulose-Bifosfato Carboxilase/metabolismo
6.
Ying Yong Sheng Tai Xue Bao ; 30(12): 4333-4343, 2019 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-31840480

RESUMO

The regulation on carbon acquisition and water loss plays a critical role in plant growth and survival. Stomata are important portals for plants to control the exchanges of carbon and water between leaves and the atmosphere. Therefore, understanding stomatal control mechanisms and modelling stomatal conductivity are indispensable to accurately simulate carbon and water cycling in terrestrial ecosystems. As global climate change is accelerating in recent years, drought events have become more and more frequent and thus profoundly affect the survival, growth and distribution of plants. In order to deeply understand the underlying mechanism of carbon-water coupling of plants and predict the dynamics of plants and communities under global changes, it is crucial to explore responses of stomatal regulation of plants to drought stress. In this review, we synthesized recent research progress on mechanisms and modeling of plant stomatal regulation under drought stress. First, this review described the active and passive regulation of plant stomatal control in response to drought stress, and discussed the evolution of plant stomatal regulation, including the passive hydraulic regulation of ferns and lycophytes, the active regulation of angiosperms, and the dual-control mechanism of gymnosperms that was proposed as an important transitional type during evolution from ferns to angiosperms. Then, we analyzed the relationship between stomatal and hydraulic regulations, and discussed the debates on the decoupling of plant water potential from stomatal conductivity. The application of stomatal-conductivity optimization models was introduced based on the water use efficiency hypothesis and the maximum carbon gain hypothesis. The model based on the latter had a greater potential of prediction and practical application. Finally, we proposed two issues that should be urgently addressed: 1) to scale up the research of plant stomatal regulation from leaf or individual to ecosystem or even larger scales so as to improve the mechanistic models of carbon and water cycling in terrestrial ecosystems; and 2) to quantify the hydroactive feedback processes of plant stomatal regulation so as to modify current hydraulics models of plant stomatal function.


Assuntos
Secas , Gleiquênias , Ecossistema , Folhas de Planta , Estômatos de Plantas , Transpiração Vegetal , Água
7.
PLoS Comput Biol ; 15(10): e1007429, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31658257

RESUMO

The plant hormone abscisic acid (ABA) promotes stomatal closure via multifarious cellular signaling cascades. Our previous comprehensive reconstruction of the stomatal closure network resulted in an 81-node network with 153 edges. Discrete dynamic modeling utilizing this network reproduced over 75% of experimental observations but a few experimentally supported results were not recapitulated. Here we identify predictions that improve the agreement between model and experiment. We performed dynamics-preserving network reduction, resulting in a condensed 49 node and 113 edge stomatal closure network that preserved all dynamics-determining network motifs and reproduced the predictions of the original model. We then utilized the reduced network to explore cases in which experimental activation of internal nodes in the absence of ABA elicited stomatal closure in wet bench experiments, but not in our in silico model. Our simulations revealed that addition of a single edge, which allows indirect inhibition of any one of three PP2C protein phosphatases (ABI2, PP2CA, HAB1) by cytosolic Ca2+ elevation, resolves the majority of the discrepancies. Consistent with this hypothesis, we experimentally show that Ca2+ application to cellular lysates at physiological concentrations inhibits PP2C activity. The model augmented with this new edge provides new insights into the role of cytosolic Ca2+ oscillations in stomatal closure, revealing a mutual reinforcement between repeated increases in cytosolic Ca2+ concentration and a self-sustaining feedback circuit inside the signaling network. These results illustrate how iteration between model and experiment can improve predictions of highly complex cellular dynamics.


Assuntos
Estômatos de Plantas/metabolismo , Proteína Fosfatase 2C/metabolismo , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Simulação por Computador , Modelos Estatísticos , Fosfoproteínas Fosfatases/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/metabolismo
8.
PLoS Pathog ; 15(10): e1008094, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31652291

RESUMO

Stomatal closure defense and apoplastic defense are two major immunity mechanisms restricting the entry and propagation of microbe pathogens in plants. Surprisingly, activation of plant intracellular immune receptor NLR genes, while enhancing whole plant disease resistance, was sometimes linked to a defective stomatal defense in autoimmune mutants. Here we report the use of high temperature and genetic chimera to investigate the inter-dependence of stomatal and apoplastic defenses in autoimmunity. High temperature inhibits both stomatal and apoplastic defenses in the wild type, suppresses constitutive apoplastic defense responses and rescues the deficiency of stomatal closure response in autoimmune mutants. Chimeric plants have been generated to activate NLR only in guard cells or the non-guard cells. NLR activation in guard cells inhibits stomatal closure defense response in a cell autonomous manner likely through repressing ABA responses. At the same time, it leads to increased whole plant resistance accompanied by a slight increase in apoplastic defense. In addition, NLR activation in both guard and non-guard cells affects stomatal aperture and water potential. This study thus reveals that NLR activation has a differential effect on immunity in a cell type specific matter, which adds another layer of immune regulation with spatial information.


Assuntos
Arabidopsis/imunologia , Resistência à Doença/genética , Proteínas NLR/metabolismo , Estômatos de Plantas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Autoimunidade/genética , Autoimunidade/imunologia , Quimera/genética , Regulação da Expressão Gênica de Plantas , Temperatura Alta , Receptores Imunológicos/metabolismo
10.
Plant Physiol Biochem ; 144: 22-34, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31550610

RESUMO

The recoveries of mesophyll (gm) and stomatal conductance to CO2 (gsc) after soil rewatering have received considerable attention in recent years, but the recovery mechanisms involving leaf anatomy and physiological activities are poorly understood. Moreover, it is also unclear whether leaf gas-phase conductance (gias) or liquid-phase conductance (gliq) is the main factor promoting gm recovery. By simultaneously using gas exchange and chlorophyll fluorescence, we measured the recoveries of gm and gsc in saplings of Manchurian ash (Fraxinus mandshurica Rupr.) and Mongolian oak (Quercus mongolica Fish. ex Ledeb) exposed to two initial water stress (medium water stress, MW, and severe water stress, SW) and following rewatering. Furthermore, leaf anatomical characteristics and the activities of aquaporin (AQP) and carbonic anhydrase (CA) were measured to explain the mechanisms of gm and gsc recoveries. The results showed that (i) both gm and gsc were partly recovered after rewatering, and the recoveries decreased with initial water stress in both species. (ii) The gm recovery was much greater in Mongolian oak than in Manchurian ash, while the gsc recovery was much greater in Manchurian ash. Consequently, the photosynthesis recovery in Manchurian ash was mostly affected by gsc recovery, while that in Mongolian oak was mostly affected by gm recovery. (iii) The gm recovery mainly resulted from the great increase in leaf gliq after rewatering rather than that in gias, as gias had a negative effect on gm recovery. The stomatal opening status improved after rewatering, as the stomatal pore size (SS) increased, greatly promoting gsc recovery. In addition, the activities of both AQP and CA increased after rewatering, which improved CO2 transmembrane transports and greatly promoted gm and gsc recoveries.


Assuntos
Células do Mesofilo/metabolismo , Folhas de Planta/metabolismo , Estômatos de Plantas/metabolismo , Quercus/metabolismo , Água/metabolismo
11.
Elife ; 82019 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-31524595

RESUMO

In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Regulação da Expressão Gênica de Plantas , Canais Iônicos/metabolismo , Estômatos de Plantas/fisiologia , Proteínas Quinases/metabolismo , Arabidopsis/efeitos dos fármacos , Quitina/imunologia , Fungos/química , Estômatos de Plantas/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Reconhecimento de Padrão/metabolismo
12.
Sci Total Environ ; 692: 713-722, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539979

RESUMO

Nocturnal transpiration may be a key factor influencing water use in plants. Tropospheric ozone (O3) and availability of nutrients such as nitrogen (N) and phosphorus (P) in the soil can affect daytime water use through stomata, but the combined effects of O3, N and P on night-time stomatal conductance (gs) are not known. We investigated the effects of O3 and soil availability of N and P on nocturnal gs and the dynamics of stomatal response after leaf severing in an O3-sensitive poplar clone (Oxford) subjected to combined treatments over a growing season in an O3 free air controlled exposure (FACE) facility. The treatments were two soil N levels (0 and 80 kg N ha-1; N0 and N80), three soil P levels (0, 40 and 80 kg P ha-1; P0, P40 and P80) and three O3 levels (ambient concentration, AA [35.0 ppb as hourly mean]; 1.5 × AA; 2.0 × AA). The analysis of stomatal dynamics after leaf severing suggested that O3 impaired stomatal closure execution. As a result, nocturnal gs was increased by 2.0 × AA O3 in August (+39%) and September (+108%). Night-time gs was correlated with POD0 (phytotoxic O3 dose) and increased exponentially after 40 mmol m-2 POD0. Such increase of nocturnal gs was attributed to the emission of ethylene due to 2.0 × AA O3 exposure, while foliar abscisic acid (ABA) or indole-3-acetic acid (IAA) did not affect gs at night. Interestingly, the O3-induced stomatal opening at night was limited by N treatments in August, but not limited in September. Phosphorus decreased nocturnal gs, although P did not modify the O3-induced stomatal dysfunction. The results suggest that the increased nocturnal gs may be associated with a need to improve N acquisition to cope with O3 stress.


Assuntos
Nitrogênio/fisiologia , Ozônio/efeitos adversos , Fósforo/fisiologia , Estômatos de Plantas/efeitos dos fármacos , Populus/efeitos dos fármacos , Ritmo Circadiano , Fertilizantes/análise , Itália , Estômatos de Plantas/fisiologia , Populus/fisiologia
13.
Plant Physiol Biochem ; 143: 340-350, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31541989

RESUMO

Drought, one of the most acute abiotic stressors plants encountered, can adversely affect plants growth and development. The fast adjustment of stomatal aperture is necessary for effective drought tolerance in plants. Anion channels were identified as important controllers of stomatal closing via mediating anion efflux. The present study reports the isolation and identification of a SLAC (SLOW ANION CHANNEL-ASSOCIATED 1) ortholog from an ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. (AmSLAC1), which is functionally conserved for ABA and drought induced stomata closure. AmSLAC1 was primarily expressed in shoots, especially in guard cells. The transcription of AmSLAC1 was induced in response to ABA and PEG treatments, implying the potential involvement in ABA-induced drought stress responses. Fluorescence observation suggested that AmSLAC1 was localized in the plasma membrane. BiFC asssays demonstrated an interaction between AmSLAC1 and the typical calcium-dependent protein kinases AmCPK6. Ectopic expression of AmSLAC1 restores a slac1-defective phenotype in Arabidopsis. Furthermore, anion conductance mediated by AmSLAC1 can be activated by AmCPK6 in Xenopus oocytes. Taken together, these results demonstrate that the expression of AmSLAC1 enables the complement of the phenotypes of Arabidopsis slac1 mutants, indicating that AmSLAC1, as an anion channel and regulated by AmCPK6, is functionally conserved for ABA and drought induced stomata closure.


Assuntos
Secas , Fabaceae/metabolismo , Estômatos de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fabaceae/genética , Fabaceae/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia
14.
Nat Commun ; 10(1): 4021, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492889

RESUMO

A detailed understanding of abiotic stress tolerance in plants is essential to provide food security in the face of increasingly harsh climatic conditions. Glucosinolates (GLSs) are secondary metabolites found in the Brassicaceae that protect plants from herbivory and pathogen attack. Here we report that in Arabidopsis, aliphatic GLS levels are regulated by the auxin-sensitive Aux/IAA repressors IAA5, IAA6, and IAA19. These proteins act in a transcriptional cascade that maintains expression of GLS levels when plants are exposed to drought conditions. Loss of IAA5/6/19 results in reduced GLS levels and decreased drought tolerance. Further, we show that this phenotype is associated with a defect in stomatal regulation. Application of GLS to the iaa5,6,19 mutants restores stomatal regulation and normal drought tolerance. GLS action is dependent on the receptor kinase GHR1, suggesting that GLS may signal via reactive oxygen species. These results provide a novel connection between auxin signaling, GLS levels and drought response.


Assuntos
Adaptação Fisiológica/genética , Proteínas de Arabidopsis/genética , Secas , Glucosinolatos/metabolismo , Proteínas de Arabidopsis/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/metabolismo , Ácidos Indolacéticos/farmacologia , Modelos Genéticos , Reguladores de Crescimento de Planta/metabolismo , Reguladores de Crescimento de Planta/farmacologia , Estômatos de Plantas/genética , Estômatos de Plantas/metabolismo , Plantas Geneticamente Modificadas , Proteínas Quinases
15.
Microsc Res Tech ; 82(11): 1911-1921, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31400047

RESUMO

A number of herbal plants sold in herbal markets of Lahore are under adulteration threat which can pose harmful health effects to end-user. This adulteration problem of medicinal plants can be resolved by the implication of some valuable taxonomic parameter such as leaf epidermal anatomical characteristics. Hence, this research was aimed to provide viable anatomical markers in order to resolve this adulteration issue persisted in some common marketed medicinal plants of district Lahore, that is, Cinnamomum verum Presl., Cinnamomum tamala (Buuch.-Ham.) T.Nees&Eberm., Gymnema sylvestre (Retz.) R.Br.ex Sm., Sphaeranthus indicus Linn., Artemisia maritima Linn., Achillea millifolim L., Adhatoda vasica Nees, Butea monosperma (Lam.) Taub, and Morus nigra L. Overall multiple anatomical variations (epidermal cell shape, their length and width, type of stomata, length and width of guard cells along with presence or absence of trichomes) had been reported in the study that could be worthwhile for the correct identification of medicinal plants. Irregular shapes of epidermal cells were observed in Cinnamomum verum and Achillea millifolium while pentagonal and polygonal cells were found in their adultaerants, that is, Canella winterana and Adhatoda vasica, respectively. Types of stomata were also strikingly varied among genuine plant and its adulterant, for example, anisocytic stomata were observed in Artemisia maritima while in its adulterant (Artemisia absinthium) anomocytic stomata were found. Similarly, paracytic stomata were observed in Butea monosperma, whereas its adulterant plant (Averrhoa carambola) characteristically possessed anisocytic stomata. Hence, anatomical characteristics were proved to be a valuable taxonomic tool in resolving the adulteration issue of medicinal plants.


Assuntos
Identificação Biométrica/métodos , Contaminação de Medicamentos/prevenção & controle , Medicina Tradicional , Plantas Medicinais/anatomia & histologia , Humanos , Paquistão , Epiderme Vegetal/anatomia & histologia , Folhas de Planta/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , Plantas Medicinais/classificação , Tricomas/anatomia & histologia
16.
J Zhejiang Univ Sci B ; 20(9): 713-727, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31379142

RESUMO

Production of reactive oxygen species (ROS) is a conserved immune response primarily mediated by NADPH oxidases (NOXs), also known in plants as respiratory burst oxidase homologs (RBOHs). Most microbe-associated molecular patterns (MAMPs) trigger a very fast and transient ROS burst in plants. However, recently, we found that lipopolysaccharides (LPS), a typical bacterial MAMP, triggered a biphasic ROS burst. In this study, we isolated mutants defective in LPS-triggered biphasic ROS burst (delt) in Arabidopsis, and cloned the DELT1 gene that was shown to encode RBOHD. In the delt1-2 allele, the antepenultimate residue, glutamic acid (E919), at the C-terminus of RBOHD was mutated to lysine (K). E919 is a highly conserved residue in NADPH oxidases, and a mutation of the corresponding residue E568 in human NOX2 has been reported to be one of the causes of chronic granulomatous disease. Consistently, we found that residue E919 was indispensable for RBOHD function in the MAMP-induced ROS burst and stomatal closure. It has been suggested that the mutation of this residue in other NADPH oxidases impairs the protein's stability and complex assembly. However, we found that the E919K mutation did not affect RBOHD protein abundance or the ability of protein association, suggesting that the residue E919 in RBOHD might have a regulatory mechanism different from that of other NOXs. Taken together, our results confirm that the antepenultimate residue E is critical for NADPH oxidases and provide a new insight into the regulatory mechanisms of RBOHD.


Assuntos
Proteínas de Arabidopsis/química , Arabidopsis/metabolismo , NADPH Oxidases/química , Agrobacterium tumefaciens/metabolismo , Alelos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Técnicas Genéticas , Humanos , Lipopolissacarídeos/metabolismo , Luminescência , Mutação , NADPH Oxidase 2/química , NADPH Oxidases/genética , Estômatos de Plantas/metabolismo , Domínios Proteicos , Espécies Reativas de Oxigênio/metabolismo , Tabaco/metabolismo
17.
Nat Commun ; 10(1): 3398, 2019 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363097

RESUMO

Stomata, the microvalves on leaf surfaces, exert major influences across scales, from plant growth and productivity to global carbon and water cycling. Stomatal opening enables leaf photosynthesis, and plant growth and water use, whereas plant survival of drought depends on stomatal closure. Here we report that stomatal function is constrained by a safety-efficiency trade-off, such that species with greater stomatal conductance under high water availability (gmax) show greater sensitivity to closure during leaf dehydration, i.e., a higher leaf water potential at which stomatal conductance is reduced by 50% (Ψgs50). The gmax - Ψgs50 trade-off and its mechanistic basis is supported by experiments on leaves of California woody species, and in analyses of previous studies of the responses of diverse flowering plant species around the world. Linking the two fundamental key roles of stomata-the enabling of gas exchange, and the first defense against drought-this trade-off constrains the rates of water use and the drought sensitivity of leaves, with potential impacts on ecosystems.


Assuntos
Folhas de Planta/metabolismo , Estômatos de Plantas/metabolismo , Água/metabolismo , California , Secas , Ecossistema , Meio Ambiente , Água/análise
18.
J Plant Res ; 132(5): 705-718, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31363942

RESUMO

Direct measurements of ecophysiological processes such as leaf photosynthesis are often hampered due to the excessive time required for gas-exchange measurements and the limited availability of multiple gas analyzers. Although recent advancements in commercially available instruments have improved the ability to take measurements more conveniently, the amount of time required for each plant sample to acclimate to chamber conditions has not been sufficiently reduced. Here we describe a system of multiple gas-exchange chambers coupled with a laser spectrometer that employs tunable diode laser absorption spectroscopy (TDLAS) to measure leaf photosynthesis, stomatal conductance, and mesophyll conductance. Using four gas-exchange chambers minimizes the time loss associated with acclimation for each leaf sample. System operation is semiautomatic, and leaf temperature, humidity, and CO2 concentration can be regulated and monitored remotely by a computer system. The preliminary results with rice leaf samples demonstrated that the system is capable of high-throughput measurements, which is necessary to obtain better representativeness of the ecophysiological characteristics of plant samples.


Assuntos
Células do Mesofilo/fisiologia , Oryza/fisiologia , Fotossíntese , Folhas de Planta/fisiologia , Estômatos de Plantas/fisiologia , Análise Espectral/métodos , Botânica/métodos
19.
Environ Sci Pollut Res Int ; 26(30): 31166-31177, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31456154

RESUMO

Effect of arsenate [As(V)] on biomass, photosynthetic rate, stomatal conductance, transpiration, oxidative stress, accumulation of As, Fe, Zn, Cu and Mn and expression of NRAMP genes was investigated in As(V) tolerant and sensitive genotypes of bioenergy crop Ricinus communis. As(V) treatments (100 and 200 µM) led to significant reduction in root and leaf biomass, photosynthetic rate, stomatal conductance and transpiration in GCH 2 and GCH 4 genotypes but no significant change or increase was observed in WM and DCH 177 genotypes. No significant difference was observed in hydrogen peroxide content and lipid peroxidation in As(V)-treated tolerant genotypes compared to control, whereas these parameters enhanced significantly in As(V)-treated sensitive genotypes. GCH 2 accumulated around two times As in leaves and showed significant reduction in concentration of Zn and Mn in the leaves and roots due to 200 µM As(V) treatment compared to WM. NRAMP genes are critical for uptake and distribution of essential divalent metal cations, photosynthesis and controlled production of reactive oxygen species in plants. RcNRAMP2, RcNRAMP3 and RcNRAMP5 genes showed differential expression in response to 200 µM As(V) in GCH 2 and WM suggesting that NRAMP genes are associated with differential responses of WM and GCH 2 genotypes to As(V) stress.


Assuntos
Arsênico/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Ricinus/efeitos dos fármacos , Ricinus/fisiologia , Poluentes Ambientais/toxicidade , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genótipo , Peróxido de Hidrogênio/metabolismo , Metais/metabolismo , Estresse Oxidativo/fisiologia , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico/efeitos dos fármacos
20.
PLoS Genet ; 15(8): e1008377, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31465456

RESUMO

Intercellular communication in adjacent cell layers determines cell fate and polarity, thus orchestrating tissue specification and differentiation. Here we use the maize stomatal apparatus as a model to investigate cell fate determination. Mutations in ZmBZU2 (bizui2, bzu2) confer a complete absence of subsidiary cells (SCs) and normal guard cells (GCs), leading to failure of formation of mature stomatal complexes. Nuclear polarization and actin accumulation at the interface between subsidiary mother cells (SMCs) and guard mother cells (GMCs), an essential pre-requisite for asymmetric cell division, did not occur in Zmbzu2 mutants. ZmBZU2 encodes a basic helix-loop-helix (bHLH) transcription factor, which is an ortholog of AtMUTE in Arabidopsis (BZU2/ZmMUTE). We found that a number of genes implicated in stomatal development are transcriptionally regulated by BZU2/ZmMUTE. In particular, BZU2/ZmMUTE directly binds to the promoters of PAN1 and PAN2, two early regulators of protodermal cell fate and SMC polarization, consistent with the low levels of transcription of these genes observed in bzu2-1 mutants. BZU2/ZmMUTE has the cell-to-cell mobility characteristic similar to that of BdMUTE in Brachypodium distachyon. Unexpectedly, BZU2/ZmMUTE is expressed in GMC from the asymmetric division stage to the GMC division stage, and especially in the SMC establishment stage. Taken together, these data imply that BZU2/ZmMUTE is required for early events in SMC polarization and differentiation as well as for the last symmetrical division of GMCs to produce the two GCs, and is a master determinant of the cell fate of its neighbors through cell-to-cell communication.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/metabolismo , Células-Tronco/fisiologia , Zea mays/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Comunicação Celular/genética , Diferenciação Celular/genética , Divisão Celular/genética , Polaridade Celular/genética , Mutação , Proteínas de Plantas/genética , Estômatos de Plantas/citologia , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética
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