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1.
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
2.
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
3.
Environ Pollut ; 252(Pt B): 1687-1697, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31284211

RESUMO

The impact of ozone (O3) pollution events on the plant drought response needs special attention because spring O3 episodes are often followed by summer drought. By causing stomatal sluggishness, O3 could affect the stomatal dynamic during a subsequent drought event. In this context, we studied the impact of O3 exposure and water deficit (in the presence or in the absence of O3 episode) on the stomatal closure/opening mechanisms relative to irradiance or vapour pressure deficit (VPD) variation. Two genotypes of Populus nigra x deltoides were exposed to various treatments for 21 days. Saplings were exposed to 80 ppb/day O3 for 13 days, and then to moderate drought for 7 days. The curves of the stomatal response to irradiance and VPD changes were determined after 13 days of O3 exposure, and after 21 days in the case of subsequent water deficit, and then fitted using a sigmoidal model. The main responses under O3 exposure were stomatal closure and sluggishness, but the two genotypes showed contrasting responses. During stomatal closure induced by a change in irradiance, closure was slower for both genotypes. Nonetheless, the genotypes differed in stomatal opening under light. Carpaccio stomata opened more slowly than control stomata, whereas Robusta stomata tended to open faster. These effects could be of particular interest, as stomatal impairment was still present after O3 exposure and could result from imperfect recovery. Under water deficit alone, we observed slower stomatal closure in response to VPD and irradiance, but faster stomatal opening in response to irradiance, more marked in Carpaccio. Under the combined treatment, most of the parameters showed antagonistic responses. Our results highlight that it is important to take genotype-specific responses and interactive stress cross-talk into account to improve the prediction of stomatal conductance in response to various environmental modifications.


Assuntos
Poluentes Atmosféricos/toxicidade , Ozônio/toxicidade , Estômatos de Plantas/efeitos dos fármacos , Populus/efeitos dos fármacos , Água/metabolismo , Secas , Genótipo , Modelos Teóricos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Estômatos de Plantas/genética , Populus/genética , Estações do Ano , Especificidade da Espécie , Pressão de Vapor
4.
BMC Genomics ; 20(1): 514, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31226927

RESUMO

BACKGROUND: Polyploidization, pervasive among higher plant species, enhances adaptation to water deficit, but the physiological and molecular advantages need to be investigated widely. Long non-coding RNAs (lncRNAs) are involved in drought tolerance in various crops. RESULTS: Herein, we demonstrate that tetraploidy potentiates tolerance to drought stress in cassava (Manihot esculenta Crantz). Autotetraploidy reduces transpiration by lesser extent increasing of stomatal density, smaller stomatal aperture size, or greater stomatal closure, and reducing accumulation of H2O2 under drought stress. Transcriptome analysis of autotetraploid samples revealed down-regulation of genes involved in photosynthesis under drought stress, and less down-regulation of subtilisin-like proteases involved in increasing stomatal density. UDP-glucosyltransferases were increased more or reduced less in dehydrated leaves of autotetraploids compared with controls. Strand-specific RNA-seq data (validated by quantitative real time PCR) identified 2372 lncRNAs, and 86 autotetraploid-specific lncRNAs were differentially expressed in stressed leaves. The co-expressed network analysis indicated that LNC_001148 and LNC_000160 in autotetraploid dehydrated leaves regulated six genes encoding subtilisin-like protease above mentioned, thereby result in increasing the stomatal density to a lesser extent in autotetraploid cassava. Trans-regulatory network analysis suggested that autotetraploid-specific differentially expressed lncRNAs were associated with galactose metabolism, pentose phosphate pathway and brassinosteroid biosynthesis, etc. CONCLUSION: Tetraploidy potentiates tolerance to drought stress in cassava, and LNC_001148 and LNC_000160 mediate drought tolerance by regulating stomatal density in autotetraploid cassava.


Assuntos
Aclimatação/genética , Manihot/genética , RNA Longo não Codificante/fisiologia , RNA de Plantas/fisiologia , Secas , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Manihot/fisiologia , Fotossíntese/genética , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Estresse Fisiológico , Tetraploidia
5.
Plant Cell Physiol ; 60(10): 2263-2271, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31241163

RESUMO

Signal crosstalk between jasmonate and ethylene is crucial for a proper maintenance of defense responses and development. Although previous studies reported that both jasmonate and ethylene also function as modulators of stomatal movements, the signal crosstalk mechanism in stomatal guard cells remains unclear. Here, we show that the ethylene signaling inhibits jasmonate signaling as well as abscisic acid (ABA) signaling in guard cells of Arabidopsis thaliana and reveal the signaling crosstalk mechanism. Both an ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and an ethylene-releasing compound ethephon induced transient stomatal closure, and also inhibited methyl jasmonate (MeJA)-induced stomatal closure as well as ABA-induced stomatal closure. The ethylene inhibition of MeJA-induced stomatal closure was abolished in the ethylene-insensitive mutant etr1-1, whereas MeJA-induced stomatal closure was impaired in the ethylene-overproducing mutant eto1-1. Pretreatment with ACC inhibited MeJA-induced reactive oxygen species (ROS) production as well as ABA-induced ROS production in guard cells but did not suppress ABA activation of OPEN STOMATA 1 (OST1) kinase in guard cell-enriched epidermal peels. The whole-cell patch-clamp analysis revealed that ACC attenuated MeJA and ABA activation of S-type anion channels in guard cell protoplasts. However, MeJA and ABA inhibitions of Kin channels were not affected by ACC pretreatment. These results suggest that ethylene signaling inhibits MeJA signaling and ABA signaling by targeting S-type anion channels and ROS but not OST1 kinase and K+ channels in Arabidopsis guard cells.


Assuntos
Acetatos/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ciclopentanos/metabolismo , Etilenos/metabolismo , Oxilipinas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Proteínas Quinases/metabolismo , Transdução de Sinais , Ácido Abscísico/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Canais Iônicos/genética , Canais Iônicos/metabolismo , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Proteínas Quinases/genética , Espécies Reativas de Oxigênio/metabolismo
6.
New Phytol ; 223(4): 1888-1903, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31081152

RESUMO

Occurrence of stomata on both leaf surfaces (amphistomaty) promotes higher stomatal conductance and photosynthesis while simultaneously increasing exposure to potential disease agents in black cottonwood (Populus trichocarpa). A genome-wide association study (GWAS) with 2.2M single nucleotide polymorphisms generated through whole-genome sequencing found 280 loci associated with variation in adaxial stomatal traits, implicating genes regulating stomatal development and behavior. Strikingly, numerous loci regulating plant growth and response to biotic and abiotic stresses were also identified. The most significant locus was a poplar homologue of SPEECHLESS (PtSPCH1). Individuals possessing PtSPCH1 alleles associated with greater adaxial stomatal density originated primarily from environments with shorter growing seasons (e.g. northern latitudes, high elevations) or with less precipitation. PtSPCH1 was expressed in developing leaves but not developing stem xylem. In developing leaves, RNA sequencing showed patterns of coordinated expression between PtSPCH1 and other GWAS-identified genes. The breadth of our GWAS results suggests that the evolution of amphistomaty is part of a larger, complex response in plants. Suites of genes underpin this response, retrieved through genetic association to adaxial stomata, and show coordinated expression during development. We propose that the occurrence of amphistomaty in P. trichocarpa involves PtSPCH1 and reflects selection for supporting rapid growth over investment in immunity.


Assuntos
Padronização Corporal , Proteínas de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Populus/fisiologia , Alelos , Clima , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Estudo de Associação Genômica Ampla , Genótipo , Geografia , Fenótipo , Desenvolvimento Vegetal , Imunidade Vegetal/genética , Proteínas de Plantas/genética , Estômatos de Plantas/genética , Polimorfismo de Nucleotídeo Único/genética , Populus/genética , Populus/crescimento & desenvolvimento , Populus/imunologia , Característica Quantitativa Herdável , Especificidade da Espécie
7.
Plant Physiol Biochem ; 140: 18-26, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31078052

RESUMO

Arabidopsis thaliana cyclic nucleotide-gated ion channel gene 4 (AtCNGC4) loss-of-function mutant dnd2 exhibits elevated accumulation of salicylic acid (SA), dwarfed morphology, reduced hypersensitive response (HR), altered disease resistance and spontaneous lesions on plant leaves. An orthologous barley mutant, nec1, has been reported to over-accumulate indole-3-acetic acid (IAA) and to exhibit changes in stomatal regulation in response to exogenous auxin. Here we show that the Arabidopsis dnd2 over-accumulates both IAA and abscisic acid (ABA) and displays related phenotypic and physiological changes, such as, reduced stomatal size, higher stomatal density and stomatal index. dnd2 showed increased salt tolerance in root growth assay and significantly reduced stomatal conductance, while maintaining near wt reaction in stomatal conductance upon external application of ABA, and probably consequently increased drought stress tolerance. Introduction of both sid2-1 and fmo1 into dnd2 background resulting in removal of SA did not alter stomatal conductance. Hence, the closed stomata of dnd2 is probably a result of increased ABA levels and not increased SA levels. The triple dnd2sid2abi1-1 mutant exhibited intermediate stomatal conductance compared to dnd2 and abi1-1 (ABA insensitive, open stomata), while the response to external ABA was as in abi1-1 suggesting that reduced stomatal conductance in dnd2 is not due to impaired ABA signaling. In conclusion, Arabidopsis dnd2 mutant exhibited ABA overaccumulation and stomatal phenotypes, which may contribute to the observed improvement in drought stress resistance. Thus, Arabidopsis dnd2 mutant may serve as a model for studying crosstalk between biotic and abiotic stress and hormonal response in plants.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Ácidos Indolacéticos/metabolismo , Estômatos de Plantas/metabolismo , Proteínas de Arabidopsis/genética , Secas , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Hordeum/genética , Hordeum/metabolismo , Estômatos de Plantas/genética
8.
Planta ; 250(2): 643-655, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31144110

RESUMO

MAIN CONCLUSION: Trehalose increased drought tolerance of tomato plants, accompanied by reduced water loss and closed stomata, which was associated with the upregulated ABA signaling-related genes expression, but not in ABA accumulation. Drought is one of the principal abiotic stresses that negatively influence the growth of plant and yield. Trehalose has great agronomic potential to improve the stress tolerance of plants. However, little information is available on the role of ABA and its signaling components in trehalose-induced drought tolerance. The aim of this study is to elucidate the potential mechanism by which trehalose regulates ABA in response to drought stress. In this study, 6-week-old tomato (Solanum lycopersicum cv. Ailsa Craig) plants were treated with 0 or 15.0 mM trehalose solution. Results showed that trehalose treatment significantly enhanced drought tolerance of tomato plants, accompanied by encouraged stomatal closure and protected chloroplast ultrastructure. Compared with controls, trehalose-treated plants showed lower hydrogen peroxide content and higher antioxidant enzymes activities, which contributed to alleviate oxidative damage caused by drought. Moreover, trehalose treatment decreased ABA content, which was followed by the downregulation of ABA biosynthesis genes expression and the upregulation of ABA catabolism genes expression. In contrast, exogenous trehalose upregulated transcript levels of ABA signaling-related genes, including SlPYL1/3/4/5/6/7/9, SlSnRK2.3/4, SlAREB1/2, and SlDREB1. These results suggested that trehalose treatment enhanced drought tolerance of tomato plants, and it's ABA signaling rather than ABA metabolism that was involved in trehalose-induced drought tolerance in tomato plants. These findings provide evidence for the physiological role of trehalose and bring about a new understanding of the possible relationship between trehalose and ABA.


Assuntos
Ácido Abscísico/metabolismo , Lycopersicon esculentum/fisiologia , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/metabolismo , Transdução de Sinais , Trealose/farmacologia , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Secas , Lycopersicon esculentum/genética , Lycopersicon esculentum/ultraestrutura , Fenótipo , Proteínas de Plantas/genética , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Estômatos de Plantas/ultraestrutura , Estresse Fisiológico
9.
Planta ; 250(1): 115-127, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30941570

RESUMO

MAIN CONCLUSION: Nocturnal transpiration, through its circadian control, plays a role in modulating daytime transpiration response to increasing evaporative demand, to potentially enable drought tolerance in wheat. Limiting plant transpiration rate (TR) in response to increasing vapor pressure deficit (VPD) has been suggested to enable drought tolerance through water conservation. However, there is very little information on the extent of diversity of TR response curves to "true" VPD (i.e., independent from temperature). Furthermore, new evidence indicate that water-saving could operate by modulating nocturnal TR (TRN), and that this response might be coupled to daytime gas exchange. Based on 3 years of experimental data on a diverse group of 77 genotypes from 25 countries and 5 continents, a first goal of this study was to characterize the functional diversity in daytime TR responses to VPD and TRN in wheat. A second objective was to test the hypothesis that these traits could be coupled through the circadian clock. Using a new gravimetric phenotyping platform that allowed for independent temperature and VPD control, we identified three and fourfold variation in daytime and nighttime responses, respectively. In addition, TRN was found to be positively correlated with slopes of daytime TR responses to VPD, and we identified pre-dawn variation in TRN that likely mediated this relationship. Furthermore, pre-dawn increase in TRN positively correlated with the year of release among drought-tolerant Australian cultivars and with the VPD threshold at which they initiated water-saving. Overall, the study indicates a substantial diversity in TR responses to VPD that could be leveraged to enhance fitness under water-limited environments, and that TRN and its circadian control may play an important role in the expression of water-saving.


Assuntos
Relógios Circadianos/fisiologia , Transpiração Vegetal/fisiologia , Triticum/fisiologia , Água/metabolismo , Secas , Genótipo , Fenótipo , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Temperatura Ambiente , Triticum/genética , Pressão de Vapor
10.
Science ; 363(6434): 1456-1459, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30923223

RESUMO

Stomata serve dual and often conflicting roles, facilitating carbon dioxide influx into the plant leaf for photosynthesis and restricting water efflux via transpiration. Strategies for reducing transpiration without incurring a cost for photosynthesis must circumvent this inherent coupling of carbon dioxide and water vapor diffusion. We expressed the synthetic, light-gated K+ channel BLINK1 in guard cells surrounding stomatal pores in Arabidopsis to enhance the solute fluxes that drive stomatal aperture. BLINK1 introduced a K+ conductance and accelerated both stomatal opening under light exposure and closing after irradiation. Integrated over the growth period, BLINK1 drove a 2.2-fold increase in biomass in fluctuating light without cost in water use by the plant. Thus, we demonstrate the potential of enhancing stomatal kinetics to improve water use efficiency without penalty in carbon fixation.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Ciclo do Carbono , Estômatos de Plantas/metabolismo , Potássio/metabolismo , Água/metabolismo , Arabidopsis/efeitos da radiação , Membrana Celular/metabolismo , Cinética , Luz , Optogenética , Fotossíntese , Estômatos de Plantas/genética , Estômatos de Plantas/efeitos da radiação , Canais de Potássio/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo
11.
Plant Sci ; 280: 397-407, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30824018

RESUMO

MhYTP1 is involved in post-transcriptional regulation as a member of YT521-homology (YTH) domain-containing RNA-binding proteins. We previously cloned MhYTP1 and found it participated in various biotic and abiotic stress responses. However, its function in long-term moderate drought has not been verified. Thus, we explored its biological role in response to drought. Under drought condition, the net photosynthesis rate (Pn) and water use efficiency (WUE) were significantly elevated in MhYTP1-overexpressing (OE) apple plants when compared with the non-transgenic (NT) controls. Further analysis indicated MhYTP1 expression was associated with elevated ABA content, increased stomatal density and reduced stomatal aperture. In addition, to gain insight into the function of stem-specific expression of MhYTP1, grafting experiments were performed. Interestingly, lower transpiration rate (Tr) and higher WUE were observed when transgenic plants were used as scions as opposed to rootstocks and when transgenic rather than NT plants were used as rootstocks, indicating MhYTP1 plays crucial roles in grafted plants. These results define a function for MhYTP1 in promoting tolerance to drought conditions, and suggest that MhYTP1 can serve as a candidate gene for future apple drought resistance breeding with the help of biotechnology.


Assuntos
Ácido Abscísico/metabolismo , Malus/genética , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Ligação a RNA/metabolismo , Água/metabolismo , Secas , Expressão Gênica , Malus/fisiologia , Componentes Aéreos da Planta/genética , Componentes Aéreos da Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas , Proteínas de Ligação a RNA/genética , Estresse Fisiológico
12.
J Biol Chem ; 294(15): 6142-6156, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30770467

RESUMO

In plants, strict regulation of stomatal pores is critical for modulation of CO2 fixation and transpiration. Under certain abiotic and biotic stressors, pore closure is initiated through anionic flux, with calcium (Ca2+) playing a central role. The aluminum-activated malate transporter 12 (ALMT12) is a malate-activated, voltage-dependent member of the aluminum-activated malate transporter family that has been implicated in anionic flux from guard cells controlling the stomatal aperture. Herein, we report the characterization of the regulatory mechanisms mediating channel activities of an ALMT from the grass Brachypodium distachyon (BdALMT12) that has the highest sequence identity to Arabidopsis thaliana ALMT12. Electrophysiological studies in a heterologous cell system confirmed that this channel is malate- and voltage-dependent. However, this was shown to be true only in the presence of Ca2+ Although a general kinase inhibitor increased the current density of BdALMT12, a calmodulin (CaM) inhibitor reduced the Ca2+-dependent channel activation. We investigated the physiological relevance of the CaM-based regulation in planta, where stomatal closure, induced by exogenous Ca2+ ionophore and malate, was shown to be inhibited by exogenous application of a CaM inhibitor. Subsequent analyses revealed that the double substitutions R335A/R338A and R335A/K342A, within a predicted BdALMT12 CaM-binding domain (CBD), also decreased the channels' ability to activate. Using isothermal titration calorimetry and CBD-mimetic peptides, as well as CaM-agarose affinity pulldown of full-length recombinant BdALMT12, we confirmed the physical interaction between the CBD and CaM. Together, these findings support a co-regulatory mechanism of BdALMT12 activation by malate, and Ca2+/CaM, emphasizing that a complex regulatory network modulates BdALMT12 activity.


Assuntos
Brachypodium , Cálcio , Calmodulina , Transportadores de Ânions Orgânicos , Proteínas de Plantas , Estômatos de Plantas , Substituição de Aminoácidos , Brachypodium/química , Brachypodium/genética , Brachypodium/metabolismo , Cálcio/química , Cálcio/metabolismo , Calmodulina/química , Calmodulina/genética , Calmodulina/metabolismo , Ativação do Canal Iônico/fisiologia , Malatos/química , Malatos/metabolismo , Mutação de Sentido Incorreto , Transportadores de Ânions Orgânicos/química , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/química , Estômatos de Plantas/genética , Estômatos de Plantas/metabolismo
13.
Development ; 146(3)2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30665887

RESUMO

In the Arabidopsis stomatal lineage, cells transit through several distinct precursor identities, each characterized by unique cell division behaviors. Flexibility in the duration of these precursor phases enables plants to alter leaf size and stomatal density in response to environmental conditions; however, transitions between phases must be complete and unidirectional to produce functional and correctly patterned stomata. Among direct transcriptional targets of the stomatal initiating factor SPEECHLESS, a pair of genes, SOL1 and SOL2, are required for effective transitions in the lineage. We show that these two genes, which are homologs of the LIN54 DNA-binding components of the mammalian DREAM complex, are expressed in a cell cycle-dependent manner and regulate cell fate and division properties in the self-renewing early lineage. In the terminal division of the stomatal lineage, however, these two proteins appear to act in opposition to their closest paralog, TSO1, revealing complexity in the gene family that may enable customization of cell divisions in coordination with development.


Assuntos
Arabidopsis/metabolismo , Ciclo Celular/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Estômatos de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/biossíntese , Receptores de Superfície Celular/biossíntese , Arabidopsis/genética , Estômatos de Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Receptores de Superfície Celular/genética
14.
New Phytol ; 221(2): 866-880, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30169890

RESUMO

The photosynthetic machinery of plants must be regulated to maximize the efficiency of light reactions and CO2 fixation. Changes in free Ca2+ in the stroma of chloroplasts have been observed at the transition between light and darkness, and also in response to stress stimuli. Such Ca2+ dynamics have been proposed to regulate photosynthetic capacity. However, the molecular mechanisms of Ca2+ fluxes in the chloroplasts have been unknown. By employing a Ca2+ reporter-based approach, we identified two chloroplast-localized Ca2+ transporters in Arabidopsis thaliana, BICAT1 and BICAT2, that determine the amplitude of the darkness-induced Ca2+ signal in the chloroplast stroma. BICAT2 mediated Ca2+ uptake across the chloroplast envelope, and its knockout mutation strongly dampened the dark-induced [Ca2+ ]stroma signal. Conversely, this Ca2+ transient was increased in knockout mutants of BICAT1, which transports Ca2+ into the thylakoid lumen. Knockout mutation of BICAT2 caused severe defects in chloroplast morphology, pigmentation and photosynthetic light reactions, rendering bicat2 mutants barely viable under autotrophic growth conditions, while bicat1 mutants were less affected. These results show that BICAT transporters play a role in chloroplast Ca2+ homeostasis. They are also involved in the regulation of photosynthesis and plant productivity. Further work will be required to reveal whether the effect on photosynthesis is a direct result of their role as Ca2+ transporters.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Cálcio/metabolismo , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Cloroplastos/genética , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Escuridão , Genes Reporter , Homeostase , Fotossíntese , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Protoplastos
15.
New Phytol ; 221(2): 988-1000, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30117535

RESUMO

The N-end rule pathway is a highly conserved constituent of the ubiquitin proteasome system, yet little is known about its biological roles. Here we explored the role of the N-end rule pathway in the plant immune response. We investigated the genetic influences of components of the pathway and known protein substrates on physiological, biochemical and metabolic responses to pathogen infection. We show that the glutamine (Gln) deamidation and cysteine (Cys) oxidation branches are both components of the plant immune system, through the E3 ligase PROTEOLYSIS (PRT)6. In Arabidopsis thaliana Gln-specific amino-terminal (Nt)-amidase (NTAQ1) controls the expression of specific defence-response genes, activates the synthesis pathway for the phytoalexin camalexin and influences basal resistance to the hemibiotroph pathogen Pseudomonas syringae pv tomato (Pst). The Nt-Cys ETHYLENE RESPONSE FACTOR VII transcription factor substrates enhance pathogen-induced stomatal closure. Transgenic barley with reduced HvPRT6 expression showed enhanced resistance to Ps. japonica and Blumeria graminis f. sp. hordei, indicating a conserved role of the pathway. We propose that that separate branches of the N-end rule pathway act as distinct components of the plant immune response in flowering plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Doenças das Plantas/imunologia , Imunidade Vegetal , Pseudomonas syringae/fisiologia , Ubiquitina-Proteína Ligases/metabolismo , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Ascomicetos/fisiologia , Etilenos/metabolismo , Hordeum/genética , Hordeum/imunologia , Hordeum/microbiologia , Oxirredução , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Planta/metabolismo , Estômatos de Plantas/genética , Estômatos de Plantas/imunologia , Estômatos de Plantas/microbiologia , Proteólise , Ubiquitina-Proteína Ligases/genética
16.
New Phytol ; 222(1): 84-90, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30444541

RESUMO

Contents Summary 84 I. Introduction 84 II. Stomatal form and biomechanics 85 III. Stomatal function 86 IV. Evolution of guard cell ion channels 87 V. Conclusions 88 Acknowledgements 88 Author contributions 88 References 88 SUMMARY: Stomatal pores with apertures that can be adjusted by changes in guard cell turgor have facilitated plant success in dry environments. We explore their evolutionary origins, considering recent findings from bryophytes. Unlike vascular plant stomata, which close to prevent water loss, bryophyte stomata become locked open to promote spore desiccation. We find that the families of ion channels, known to control stomatal movements in angiosperms, are ancient and represented across extant land plants. However, although angiosperm guard cells express specific ion channel genes, none appear specifically expressed in stomata-bearing moss tissues. Given the evolutionary shift in stomatal function from promotion to prevention of water loss, we postulate that ion channels adopted guard cell-specific functions after the divergence of bryophytes.


Assuntos
Movimento , Osmose , Estômatos de Plantas/fisiologia , Fenômenos Biomecânicos , Canais Iônicos/metabolismo , Modelos Biológicos , Estômatos de Plantas/citologia , Estômatos de Plantas/genética
17.
Plant Mol Biol ; 99(1-2): 113-122, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30536042

RESUMO

KEY MESSAGE: In this manuscript, we demonstrated the negative role of CPK9 in stomatal ABA signaling, and both CPK9 and CPK33 for accurate guard cell function was explored via cpk9/cpk33 double mutants' phenotype. Abscisic acid (ABA) can inhibit stomatal opening and promote stomatal closure by regulating ion channel activity in guard cell membranes. As an important second messenger, calcium (Ca2+) is essentially needed in ABA regulation of stomatal movement. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central Ca2+ signal transduction in plants. Here, we report the functional characterization of CPK9 in Arabidopsis stomatal ABA signaling. CPK9 had high expression in guard cells and the protein was subcellularly located in the cell membrane. A loss-of-function mutant cpk9 showed a much more sensitive phenotype to ABA regulation of stomatal movement and ion channel activity, while CPK9 overexpression lines had opposite phonotypes. These findings demonstrated the negative role of CPK9 in stomatal ABA signaling. As the closest homolog of CPK33, we also proved that stomatal movement of the cpk9/cpk33 double mutants was more sensitive to ABA than either single mutants. These results revealed the role of CPK9 in guard cells, and the need of both CPK9 and CPK33 for accurate guard cell function.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Cálcio/metabolismo , Canais Iônicos/metabolismo , Proteínas Quinases/metabolismo , Transdução de Sinais , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Membrana Celular/metabolismo , Genes Reporter , Canais Iônicos/genética , Transporte de Íons , Mutação , Reguladores de Crescimento de Planta/metabolismo , Estômatos de Plantas/genética , Proteínas Quinases/genética
18.
Nat Plants ; 4(12): 1071-1081, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30518839

RESUMO

The frequency and orientation of cell division are regulated by intercellular signalling molecules; however, tissue-specific regulatory systems for cell divisions are only partially understood. Here, we report that the peptide hormone CLAVATA3/ESR-RELATED 9/10 (CLE9/10) regulates two different developmental processes, stomatal lineage development and xylem development, through two distinct receptor systems in Arabidopsis thaliana. We show that the receptor kinase HAESA-LIKE 1 (HSL1) is a CLE9/10 receptor that regulates stomatal lineage cell division, and BARELY NO MERISTEM (BAM) class receptor kinases are CLE9/10 receptors that regulate periclinal cell division of xylem precursor cells. Both HSL1 and BAM1 bind to CLE9/10, but only HSL1 recruits SOMATIC EMBRYOGENESIS RECEPTOR KINASES as co-receptors in the presence of CLE9/10, suggesting different signalling modes for these receptor systems.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Transdução de Sinais , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Genes Reporter , Peptídeos e Proteínas de Sinalização Intercelular/genética , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Estômatos de Plantas/genética , Estômatos de Plantas/crescimento & desenvolvimento , Estômatos de Plantas/metabolismo , Feixe Vascular de Plantas/genética , Feixe Vascular de Plantas/crescimento & desenvolvimento , Feixe Vascular de Plantas/metabolismo , Regiões Promotoras Genéticas/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes de Fusão , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo
19.
J Agric Food Chem ; 66(51): 13397-13404, 2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30556691

RESUMO

Abscisic acid (ABA) is a central regulator for various developmental processes and responses to abiotic stresses in plants. However, its practical application in controlling water loss of postharvest produces is largely restrained. Herein, the present study reported that two ABA-mimicking ligands, AM1 and AMF4, markedly reduced water loss by promoting stomatal closure and effectively alleviated weight loss in spinach. AM1 and AMF4 also alleviated chlorophyll and vitamin C degradation and simultaneously reduced hydrogen peroxide and malondialdehyde (MDA) production; moreover, both enzymatic and nonenzymatic systems involved in antioxidative capacity were activated. The expression levels of SoOST1, SoSLAC1, SoRCAR3, SoPYL5, SoNCED3, and SoAREB1 were also up-regulated. These findings indicate that AM1 and AMF4 are promising as novel means for reducing water loss, maintaining visual quality, delaying senescence, and extending shelf life in leafy vegetables.


Assuntos
Ácido Abscísico/metabolismo , Antioxidantes/metabolismo , Spinacia oleracea/metabolismo , Água/metabolismo , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Ligantes , Malondialdeído/metabolismo , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/genética , Estômatos de Plantas/metabolismo , Spinacia oleracea/genética , Spinacia oleracea/crescimento & desenvolvimento
20.
Plant Sci ; 277: 100-109, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30466574

RESUMO

Late embryogenesis abundant (LEA) proteins participate in drought stress responses in plants. In the present study, the gene TaLEA3 from the drought-resistant plant Tamarix androssowii was transformed into Amur cork tree (Phellodendron amurense) via Agrobacterium tumefaciens to investigate the mechanism of stomatal closure in response to osmotic stress. Our results showed that P. amurense overexpressing TaLEA3 were resistant to drought stress by rapid stomatal closure. To study the stomatal movement regulated at the molecular level, a model system for stoma closure was established in in vitro P. amurense. In this work, we found that the increased Ca2+ accumulation in guard cells of transgenic plants caused stomatal closure and activated K+ efflux under polyethylene glycol (PEG) stress. Moreover, H+ changes might provide a needed pH condition for stomatal closure. Further, nitric oxide (NO) fluorescence was measured using an NO-specific fluorescent probe, diaminofluorescein-FM diacetate, which showed that guard cell NO fluorescence was stronger in transgenic plants compared with wild type plants. Additionally, five genes encoding nitrate reductase were up-regulated, indicating that TaLEA3 overexpression positively regulated NO biosynthesis and accumulation in the guard cells. This discovery will further our understanding of the LEA gene function and will help in engineering drought-resistant tree cultivars.


Assuntos
Phellodendron/metabolismo , Estômatos de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Secas , Óxido Nítrico/metabolismo , Phellodendron/genética , Phellodendron/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/genética , Plantas Geneticamente Modificadas/genética , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia
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