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1.
Philos Trans R Soc Lond B Biol Sci ; 372(1730)2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28808105

RESUMO

Concepts of organelle-to-nucleus signalling pathways are largely based on genetic screens involving inhibitors of chloroplast and mitochondrial functions such as norflurazon, lincomycin (LINC), antimycin A (ANT) and salicylhydroxamic acid. These inhibitors favour enhanced cellular oxidation, but their precise effects on the cellular redox state are unknown. Using the in vivo reduction-oxidation (redox) reporter, roGFP2, inhibitor-induced changes in the glutathione redox potentials of the nuclei and cytosol were measured in Arabidopsis thaliana root, epidermal and stomatal guard cells, together with the expression of nuclear-encoded chloroplast and mitochondrial marker genes. All the chloroplast and mitochondrial inhibitors increased the degree of oxidation in the nuclei and cytosol. However, inhibitor-induced oxidation was less marked in stomatal guard cells than in epidermal or root cells. Moreover, LINC and ANT caused a greater oxidation of guard cell nuclei than the cytosol. Chloroplast and mitochondrial inhibitors significantly decreased the abundance of LHCA1 and LHCB1 transcripts. The levels of WHY1, WHY3 and LEA5 transcripts were increased in the presence of inhibitors. Chloroplast inhibitors decreased AOXA1 mRNA levels, while mitochondrial inhibitors had the opposite effect. Inhibitors that are used to characterize retrograde signalling pathways therefore have similar general effects on cellular redox state and gene expression.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Núcleo Celular/metabolismo , Citosol/metabolismo , Transdução de Sinais , Antimicina A/farmacologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/efeitos dos fármacos , Cotilédone/efeitos dos fármacos , Cotilédone/metabolismo , Citosol/efeitos dos fármacos , Proteínas de Fluorescência Verde/química , Lincomicina/farmacologia , Oxirredução , Fotossíntese , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/metabolismo , Piridazinas/farmacologia
2.
Plant Physiol ; 174(3): 1384-1398, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28483881

RESUMO

The expansion of aerial organs in plants is coupled with the synthesis and deposition of a hydrophobic cuticle, composed of cutin and waxes, which is critically important in limiting water loss. While the abiotic stress-related hormone abscisic acid (ABA) is known to up-regulate wax accumulation in response to drought, the hormonal regulation of cuticle biosynthesis during organ ontogeny is poorly understood. To address the hypothesis that ABA also mediates cuticle formation during organ development, we assessed the effect of ABA deficiency on cuticle formation in three ABA biosynthesis-impaired tomato mutants. The mutant leaf cuticles were thinner, had structural abnormalities, and had a substantial reduction in levels of cutin. ABA deficiency also consistently resulted in differences in the composition of leaf cutin and cuticular waxes. Exogenous application of ABA partially rescued these phenotypes, confirming that they were a consequence of reduced ABA levels. The ABA mutants also showed reduced expression of genes involved in cutin or wax formation. This difference was again countered by exogenous ABA, further indicating regulation of cuticle biosynthesis by ABA. The fruit cuticles were affected differently by the ABA-associated mutations, but in general were thicker. However, no structural abnormalities were observed, and the cutin and wax compositions were less affected than in leaf cuticles, suggesting that ABA action influences cuticle formation in an organ-dependent manner. These results suggest dual roles for ABA in regulating leaf cuticle formation: one that is fundamentally associated with leaf expansion, independent of abiotic stress, and another that is drought induced.


Assuntos
Ácido Abscísico/farmacologia , Vias Biossintéticas/efeitos dos fármacos , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/metabolismo , Epiderme Vegetal/metabolismo , Regulação para Baixo/efeitos dos fármacos , Frutas/ultraestrutura , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Lycopersicon esculentum/anatomia & histologia , Lycopersicon esculentum/efeitos dos fármacos , Lipídeos de Membrana , Mutação/genética , Tamanho do Órgão , Fenótipo , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/ultraestrutura
3.
J Plant Physiol ; 214: 123-133, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28482333

RESUMO

Cuticular wax is the outermost thin hydrophobic layer covering the surface of aerial plant parts, which provides a primary waterproof barrier and protection against different environmental stresses. The aim of the present study was to investigate the role of ethephon, as an ethylene-releasing compound, in counteracting drought stress by modulating cuticular wax biosynthesis, water balance, and antioxidant regulation in maize seedlings. Our results showed that ethephon significantly increased the ethylene evolution rate, regulate the expression of cuticular wax synthesis regulatory gene ZmERE and the wax biosynthetic genes ZmGL1, ZmGL15, ZmFDH1, and ZmFAE1, and promote cuticular wax accumulation in maize seedlings under normal or drought stress conditions. Moreover, ethephon was shown to might markedly reduce water loss and chlorophyll leaching in leaves, and maintain higher relative water content and leaf water potential under drought stress. Ethephon significantly decreased malondialdehyde and hydrogen peroxide concentrations and electrolyte leakage, but increased the accumulation of proline and the activities of SOD, POD, and CAT. In addition, ethephon resulted in an increase in the ratio of root and shoot under drought stress. These results indicated that ethephon could improve maize performance under drought stress by modulating cuticular wax synthesis to maintain water status and membrane stability for plant growth.


Assuntos
Secas , Compostos Organofosforados/farmacologia , Plântula/metabolismo , Zea mays/metabolismo , Antioxidantes/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Zea mays/efeitos dos fármacos
4.
Plant Cell Environ ; 40(9): 1900-1915, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28558173

RESUMO

Epidermal bladder cells (EBCs) have been postulated to assist halophytes in coping with saline environments. However, little direct supporting evidence is available. Here, Chenopodium quinoa plants were grown under saline conditions for 5 weeks. One day prior to salinity treatment, EBCs from all leaves and petioles were gently removed by using a soft cosmetic brush and physiological, ionic and metabolic changes in brushed and non-brushed leaves were compared. Gentle removal of EBC neither initiated wound metabolism nor affected the physiology and biochemistry of control-grown plants but did have a pronounced effect on salt-grown plants, resulting in a salt-sensitive phenotype. Of 91 detected metabolites, more than half were significantly affected by salinity. Removal of EBC dramatically modified these metabolic changes, with the biggest differences reported for gamma-aminobutyric acid (GABA), proline, sucrose and inositol, affecting ion transport across cellular membranes (as shown in electrophysiological experiments). This work provides the first direct evidence for a role of EBC in salt tolerance in halophytes and attributes this to (1) a key role of EBC as a salt dump for external sequestration of sodium; (2) improved K+ retention in leaf mesophyll and (3) EBC as a storage space for several metabolites known to modulate plant ionic relations.


Assuntos
Atriplex/fisiologia , Chenopodium quinoa/fisiologia , Epiderme Vegetal/citologia , Tolerância ao Sal/fisiologia , Plantas Tolerantes a Sal/fisiologia , Estresse Fisiológico , Atriplex/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Chenopodium quinoa/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Transporte de Íons/efeitos dos fármacos , Células do Mesofilo/efeitos dos fármacos , Células do Mesofilo/metabolismo , Metaboloma , Fenótipo , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/fisiologia , Tolerância ao Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Sacarose/farmacologia , Ácido gama-Aminobutírico/farmacologia
5.
Plant Physiol Biochem ; 110: 108-117, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27544889

RESUMO

Utilization of CuO nanoparticles (NPs) in agriculture, as fertilizers or pesticides, requires understanding of their impact on plant metabolism. Inhibition of root elongation by CuO NPs (>10 mg Cu/kg) occurred in wheat grown in sand. Morphological changes included root hair proliferation and shortening of the zones of division and elongation. The epidermal cells in the compressed root tip were abnormal in shape and file patterning but staining with SYTOX Blue did not reveal a general increase in epidermal cell death. Inhibition of root elongation and proliferation of root hair formation occurred also in response to exogenous indole acetic acid (IAA) supplied through tryptophan metabolism by the root-colonizing bacterium, Pseudomonas chlororaphis O6. Altered root morphology caused by the CuO NPs was likely due to release of Cu from dissolution at the root surface because similar changes occurred with Cu ions (≥6 mg/kg). Use of a fluorescent probe showed the accumulation of nitric oxide (NO), required for root hair formation, was not changed by the NPs. These findings suggested that dissolution of the NPs in the rhizosphere resulted levels of Cu that modified IAA distribution to causing root shortening but permitted NO cell signaling to promote root hair proliferation.


Assuntos
Cobre/farmacologia , Nanopartículas Metálicas/administração & dosagem , Raízes de Plantas/efeitos dos fármacos , Plântula/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cobre/química , Cobre/metabolismo , Interações Hospedeiro-Patógeno , Ácidos Indolacéticos/metabolismo , Ácidos Indolacéticos/farmacologia , Nanopartículas Metálicas/química , Óxido Nítrico/metabolismo , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/microbiologia , Reguladores de Crescimento de Planta/metabolismo , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Pseudomonas/fisiologia , Rizosfera , Plântula/metabolismo , Plântula/microbiologia , Triticum/efeitos dos fármacos , Triticum/metabolismo , Triticum/microbiologia
6.
J Sci Food Agric ; 97(3): 977-983, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27235201

RESUMO

BACKGROUND: The effect of the application of benzothiadiazole (BTH) and methyl jasmonate (MeJ) at veraison on the phenolic composition of grapes from three varieties (Monastrell, Syrah and Merlot) was studied during the ripening period, using HPLC techniques to measure flavonols, anthocyanins and tannins. RESULTS: The effects of the treatments differed in the three varieties, and the maximum concentration of phenolic compounds was not always reached at the end of the ripening period but some days before harvest. At the end of ripening both treated Syrah grapes only differed from control grapes in the flavonol concentration, whereas MeJ-treated Merlot grapes presented higher anthocyanin and skin tannin contents than the control and BTH-treated grapes. Only the anthocyanin content was significantly higher in treated Monastrell grapes at the moment of harvest. CONCLUSION: The results indicate that the moment of elicitor treatment should be more studied since differences between treated and control grapes were, in general greater several days before harvest in all three varieties. © 2016 Society of Chemical Industry.


Assuntos
Acetatos/farmacologia , Agroquímicos/farmacologia , Antioxidantes/metabolismo , Produtos Agrícolas/efeitos dos fármacos , Ciclopentanos/farmacologia , Frutas/efeitos dos fármacos , Oxilipinas/farmacologia , Tiadiazóis/farmacologia , Vitis/efeitos dos fármacos , Aerossóis , Antocianinas/análise , Antocianinas/biossíntese , Antioxidantes/análise , Cromatografia Líquida de Alta Pressão , Produção Agrícola , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Flavonóis/análise , Flavonóis/biossíntese , Frutas/química , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Humanos , Valor Nutritivo , Fenóis/análise , Fenóis/metabolismo , Pigmentos Biológicos/análise , Pigmentos Biológicos/biossíntese , Epiderme Vegetal/química , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/crescimento & desenvolvimento , Epiderme Vegetal/metabolismo , Espanha , Especificidade da Espécie , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Ultravioleta , Taninos/análise , Taninos/biossíntese , Vitis/química , Vitis/crescimento & desenvolvimento , Vitis/metabolismo
7.
Plant Physiol ; 172(4): 2445-2458, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27770060

RESUMO

While the importance of cell type specificity in plant adaptive responses is widely accepted, only a limited number of studies have addressed this issue at the functional level. We have combined electrophysiological, imaging, and biochemical techniques to reveal the physiological mechanisms conferring higher sensitivity of apical root cells to salinity in barley (Hordeum vulgare). We show that salinity application to the root apex arrests root growth in a highly tissue- and treatment-specific manner. Although salinity-induced transient net Na+ uptake was about 4-fold higher in the root apex compared with the mature zone, mature root cells accumulated more cytosolic and vacuolar Na+, suggesting that the higher sensitivity of apical cells to salt is not related to either enhanced Na+ exclusion or sequestration inside the root. Rather, the above differential sensitivity between the two zones originates from a 10-fold difference in K+ efflux between the mature zone and the apical region (much poorer in the root apex) of the root. Major factors contributing to this poor K+ retention ability are (1) an intrinsically lower H+-ATPase activity in the root apex, (2) greater salt-induced membrane depolarization, and (3) a higher reactive oxygen species production under NaCl and a larger density of reactive oxygen species-activated cation currents in the apex. Salinity treatment increased (2- to 5-fold) the content of 10 (out of 25 detected) amino acids in the root apex but not in the mature zone and changed the organic acid and sugar contents. The causal link between the observed changes in the root metabolic profile and the regulation of transporter activity is discussed.


Assuntos
Aclimatação , Hordeum/enzimologia , Hordeum/fisiologia , Raízes de Plantas/enzimologia , Potássio/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Salinidade , Estresse Fisiológico , Aclimatação/efeitos dos fármacos , Alantoína/farmacologia , Cátions/metabolismo , Hordeum/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Metabolômica , Modelos Biológicos , Especificidade de Órgãos/efeitos dos fármacos , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Sódio/metabolismo , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
8.
Plant Cell Physiol ; 57(11): 2300-2311, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27577115

RESUMO

Aerial plant surfaces are coated by a cuticular wax layer to protect against environmental stresses, such as desiccation. In this study, we investigated the functional relationship between MYB94 and MYB96 transcription factors involved in cuticular wax biosynthesis. Both MYB94 and MYB96 transcripts were abundantly expressed in the aerial organs of Arabidopsis, and significantly induced at the same or similar time points under conditions of drought. MYB94 complemented the wax-deficient phenotype of the myb96 loss-of-function mutant under both well-watered and drought stress conditions. The magnitude of decrease in total wax load in the myb94 myb96 double mutant was almost equal to the sum of the reduced wax loads in the individual myb94 and myb96 mutants under both conditions. Leaves of the myb94 myb96 mutant lost water through the cuticle faster than those of myb94 or myb96 plants. Transcript levels of wax biosynthetic genes were decreased in the single mutants, and further reduced in the double mutant, relative to the wild type, under drought and ABA treatment conditions. MYB94 and MYB96 interact with the same regions containing MYB consensus motifs in the promoter regions of wax biosynthetic genes. The data collectively indicate that MYB94 and MYB96 exert an additive effect on cuticular wax biosynthesis, which may represent an efficient adaptive mechanism of response to drought in plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Epiderme Vegetal/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Ceras/metabolismo , Ácido Abscísico/farmacologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Vias Biossintéticas/efeitos dos fármacos , Vias Biossintéticas/genética , Permeabilidade da Membrana Celular/efeitos dos fármacos , Imunoprecipitação da Cromatina , Sequência Consenso , DNA Bacteriano/genética , Secas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Técnicas de Inativação de Genes , Genes de Plantas , Teste de Complementação Genética , Mutagênese Insercional/genética , Mutação/genética , Fenótipo , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Caules de Planta/efeitos dos fármacos , Caules de Planta/genética , Regiões Promotoras Genéticas/genética , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Transativadores/química , Transativadores/genética , Fatores de Transcrição/química , Fatores de Transcrição/genética , Água
9.
Plant Physiol ; 172(3): 1732-1745, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27613850

RESUMO

Small proteins have long been overlooked due to their poor annotation and the experimental challenges they pose. However, in recent years, their role in various processes has started to emerge, opening new research avenues. Here, we present the isolation and characterization of two allelic mutants, twisted seed1-1 (tws1-1) and tws1-2, which exhibit an array of developmental and biochemical phenotypes in Arabidopsis (Arabidopsis thaliana) seeds. We have identified AT5G01075 as the subtending gene encoding a small protein of 81 amino acids localized in the endoplasmic reticulum. TWS1 is strongly expressed in seeds, where it regulates both embryo development and accumulation of storage compounds. TWS1 loss-of-function seeds exhibit increased starch, sucrose, and protein accumulation at the detriment of fatty acids. TWS1 is also expressed in vegetative and reproductive tissues, where it is responsible for proper epidermal cell morphology and overall plant growth. At the cellular level, TWS1 is responsible for cuticle deposition on epidermal cells and organization of the endomembrane system. Finally, we show that TWS1 is a single-copy gene in Arabidopsis, and it is specifically conserved among angiosperms.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/embriologia , Desenvolvimento Vegetal , Sementes/embriologia , Alelos , Sequência de Aminoácidos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Carbono/farmacologia , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mutação/genética , Fenótipo , Desenvolvimento Vegetal/efeitos dos fármacos , Desenvolvimento Vegetal/genética , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , Plantas Geneticamente Modificadas , Sementes/efeitos dos fármacos , Sementes/ultraestrutura , Vacúolos/efeitos dos fármacos , Vacúolos/metabolismo
10.
J Plant Res ; 129(5): 873-881, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27294967

RESUMO

Elucidation of the mechanism of adsorption of particles suspended in the gas-phase (aerosol) to the outer surfaces of leaves provides useful information for understanding the mechanisms of the effect of aerosol particles on the growth and physiological functions of trees. In the present study, we examined the localization of artificially deposited sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica, a typical Japanese coniferous tree species, by field-emission scanning electron microscopy. The clusters (aggregates) of carbon-based particles were deposited on the needle surface regions where epicuticular wax crystals were sparsely distributed. By contrast, no clusters of the particles were found on the needle surface regions with dense distribution of epicuticular wax crystals. Number of clusters of carbon-based particles per unit area showed statistically significant differences between regions with sparse epicuticular wax crystals and those with dense epicuticular wax crystals. These results suggest that epicuticular wax crystals affect distribution of carbon-based particles on needles. Therefore, densely distributed epicuticular wax crystals might prevent the deposition of sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica to retain the function of stomata.


Assuntos
Aerossóis/farmacologia , Carbono/farmacologia , Cryptomeria/química , Epiderme Vegetal/química , Folhas de Planta/química , Ceras/química , Cryptomeria/efeitos dos fármacos , Cristalização , Tamanho da Partícula , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/ultraestrutura
11.
Colloids Surf B Biointerfaces ; 145: 548-554, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27281240

RESUMO

With recent environmental and health concerns, biosurfactants have obtained increasing interest in replacing conventional surfactants for diverse applications. In agriculture, the use of surfactant in stimulating foliar uptake is mainly for wetting leaf surface, resisting deposition/evaporation, enhancing penetration across cuticular membrane (CM) and translocation. This paper aimed to address the improved foliar uptake by rhamnolipid (RL) in comparison with the currently used alkyl polyglucoside (APG). As found, compared with APG at 900mg/L (1×critical micellar concentration, CMC), RL at a much lower concentration of 50mg/L (1×CMC) showed much better wettability and surface activity, indicative of its high effectiveness as surfactants. Its performance on resistance to deposition and evaporation was at least as same as APG. Moreover, RL could significantly improve the penetration of herbicide glyphosate and other two small water-soluble molecules (phenol red and Fe(2+)) across CM at an equivalent efficiency as APG at 1×CMC. Finally, the greatly enhanced herbicidal actitivity of glyphosate on greenhouse plants confirmed that RL and APG could both enhance the foliar uptake including translocation. Overall, RL should be more applicable than APG in agriculture due to its more promising properties on health/environmental friendliness.


Assuntos
Glicolipídeos/farmacologia , Folhas de Planta/efeitos dos fármacos , Tensoativos/farmacologia , Clorofila/metabolismo , Glucosídeos/química , Glicina/análogos & derivados , Glicina/toxicidade , Iris (Planta)/química , Fenolsulfonaftaleína/farmacologia , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/ultraestrutura , Solubilidade , Tensão Superficial/efeitos dos fármacos , Volatilização , Água/química , Molhabilidade
12.
Plant Physiol ; 171(3): 2256-76, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27217496

RESUMO

Nod factors (NFs) are lipochitooligosaccharidic signal molecules produced by rhizobia, which play a key role in the rhizobium-legume symbiotic interaction. In this study, we analyzed the gene expression reprogramming induced by purified NF (4 and 24 h of treatment) in the root epidermis of the model legume Medicago truncatula Tissue-specific transcriptome analysis was achieved by laser-capture microdissection coupled to high-depth RNA sequencing. The expression of 17,191 genes was detected in the epidermis, among which 1,070 were found to be regulated by NF addition, including previously characterized NF-induced marker genes. Many genes exhibited strong levels of transcriptional activation, sometimes only transiently at 4 h, indicating highly dynamic regulation. Expression reprogramming affected a variety of cellular processes, including perception, signaling, regulation of gene expression, as well as cell wall, cytoskeleton, transport, metabolism, and defense, with numerous NF-induced genes never identified before. Strikingly, early epidermal activation of cytokinin (CK) pathways was indicated, based on the induction of CK metabolic and signaling genes, including the CRE1 receptor essential to promote nodulation. These transcriptional activations were independently validated using promoter:ß-glucuronidase fusions with the MtCRE1 CK receptor gene and a CK response reporter (TWO COMPONENT SIGNALING SENSOR NEW). A CK pretreatment reduced the NF induction of the EARLY NODULIN11 (ENOD11) symbiotic marker, while a CK-degrading enzyme (CYTOKININ OXIDASE/DEHYDROGENASE3) ectopically expressed in the root epidermis led to increased NF induction of ENOD11 and nodulation. Therefore, CK may play both positive and negative roles in M. truncatula nodulation.


Assuntos
Citocininas/metabolismo , Lipopolissacarídeos/metabolismo , Medicago truncatula/metabolismo , Epiderme Vegetal/metabolismo , Raízes de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Lasers , Lipopolissacarídeos/farmacologia , Medicago truncatula/genética , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Nódulos Radiculares de Plantas/genética , Nódulos Radiculares de Plantas/metabolismo , Análise de Sequência de RNA/métodos , Transdução de Sinais
13.
Plant Cell Rep ; 35(8): 1671-86, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27061906

RESUMO

KEY MESSAGE: A Sec14-like protein, ZmSEC14p , from maize was structurally analyzed and functionally tested. Overexpression of ZmSEC14p in transgenic Arabidopsis conferred tolerance to cold stress. Sec14-like proteins are involved in essential biological processes, such as phospholipid metabolism, signal transduction, membrane trafficking, and stress response. Here, we reported a phosphatidylinositol transfer-associated protein, ZmSEC14p (accession no. KT932998), isolated from a cold-tolerant maize inbred line using the cDNA-AFLP approach and RACE-PCR method. Full-length cDNA that consisted of a single open reading frame (ORF) encoded a putative polypeptide of 295 amino acids. The ZmSEC14p protein was mainly localized in the nucleus, and its transcript was induced by cold, salt stresses, and abscisic acid (ABA) treatment in maize leaves and roots. Overexpression of ZmSEC14p in transgenic Arabidopsis conferred tolerance to cold stress. This tolerance was primarily displayed by the increased germination rate, root length, plant survival rate, accumulation of proline, activities of antioxidant enzymes, and the reduction of oxidative damage by reactive oxygen species (ROS). ZmSEC14p overexpression regulated the expression of phosphoinositide-specific phospholipase C, which cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) and generates second messengers (inositol 1,4,5-trisphosphate and 1,2-diacylglycerol) in the phosphoinositide signal transduction pathways. Moreover, up-regulation of some stress-responsive genes such as CBF3, COR6.6, and RD29B in transgenic plants under cold stress could be a possible mechanism for enhancing cold tolerance. Taken together, this study strongly suggests that ZmSEC14p plays an important role in plant tolerance to cold stress.


Assuntos
Temperatura Baixa , Proteínas de Transferência de Fosfolipídeos/metabolismo , Proteínas de Plantas/metabolismo , Zea mays/metabolismo , Ácido Abscísico/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/genética , Sequência de Aminoácidos , Antioxidantes/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/fisiologia , Congelamento , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Germinação/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Cebolas/citologia , Fosfoinositídeo Fosfolipase C/metabolismo , Proteínas de Transferência de Fosfolipídeos/química , Proteínas de Transferência de Fosfolipídeos/genética , Proteínas de Transferência de Fosfolipídeos/isolamento & purificação , Filogenia , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/isolamento & purificação , Plantas Geneticamente Modificadas , Prolina/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Frações Subcelulares/metabolismo , Zea mays/efeitos dos fármacos , Zea mays/genética , Zea mays/fisiologia
14.
J Exp Bot ; 67(6): 1883-95, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26826218

RESUMO

Lamina inclination is a key agronomical character that determines plant architecture and is sensitive to auxin and brassinosteroids (BRs). Loose Plant Architecture1 (LPA1) in rice (Oryza sativa) and its Arabidopsis homologues (SGR5/AtIDD15) have been reported to control plant architecture and auxin homeostasis. This study explores the role of LPA1 in determining lamina inclination in rice. LPA1 acts as a positive regulator to suppress lamina bending. Genetic and biochemical data indicate that LPA1 suppresses the auxin signalling that interacts with C-22-hydroxylated and 6-deoxo BRs, which regulates lamina inclination independently of OsBRI1. Mutant lpa1 plants are hypersensitive to indole-3-acetic acid (IAA) during the lamina inclination response, which is suppressed by the brassinazole (Brz) inhibitor of C-22 hydroxylase involved in BR synthesis. A strong synergic effect is detected between lpa1 and d2 (the defective mutant for catalysis of C-23-hydroxylated BRs) during IAA-mediated lamina inclination. No significant interaction between LPA1 and OsBRI1 was identified. The lpa1 mutant is sensitive to C-22-hydroxylated and 6-deoxo BRs in the d61-1 (rice BRI1 mutant) background. We present evidence verifying that two independent pathways function via either BRs or BRI1 to determine IAA-mediated lamina inclination in rice. RNA sequencing analysis and qRT-PCR indicate that LPA1 influences the expression of three OsPIN genes (OsPIN1a, OsPIN1c and OsPIN3a), which suggests that auxin flux might be an important factor in LPA1-mediated lamina inclination in rice.


Assuntos
Brassinosteroides/farmacologia , Ácidos Indolacéticos/metabolismo , Oryza/fisiologia , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Transdução de Sinais , Alelos , Fenômenos Biomecânicos/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Hidroxilação , Mutação/genética , Oryza/efeitos dos fármacos , Oryza/genética , Fenótipo , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais/efeitos dos fármacos
15.
Protoplasma ; 253(5): 1211-21, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26387115

RESUMO

The allelopathic potential of leaf aqueous extract (LAE) of Calotropis procera on growth behavior, ultrastructural changes on Cassia sophera L., and cytological changes on Allium cepa L. was investigated. LAE at different concentrations (0.5, 1, 2, and 4 %) significantly reduced the root length, shoot length, and dry biomass of C. sophera. Besides, the ultrastructural changes (through scanning electron microscopy, SEM) induced in epidermal cells of 15-day-old seedlings of Cassia leaf were also noticed. The changes induced were shrinking and contraction of epidermal cells along with the formation of major grooves, canals, and cyst-like structures. The treated samples of epidermal cells no longer seem to be smooth as compared to control. LAE at different concentrations induces chromosomal aberrations and variation in shape of the interphase and prophase nucleus in A. cepa root tip cells when compared with control groups. The mitotic index in treated onion root tips decreased with increasing concentrations of the extracts. The most frequent aberrations were despiralization at prophase with the formation of micronuclei, sticky anaphase with bridges, sticky telophase, C-metaphase, etc. The results also show the induction of ghost cells, cells with membrane damage, and cells with heterochromatic nuclei by extract treatment. Upon HPLC analysis, nine phenolic acids (caffeic acid, gentisic acid, catechol, gallic acid, syringic acid, ellagic acid, resorcinol, p-coumaric acid, and p-hydroxy benzoic acid) were identified. Thus, the phenolic acids are mainly responsible for the allelopathic behavior of C. procera.


Assuntos
Calotropis/metabolismo , Cassia/crescimento & desenvolvimento , Germinação/efeitos dos fármacos , Meristema/química , Cebolas/crescimento & desenvolvimento , Extratos Vegetais/farmacologia , Folhas de Planta/metabolismo , Alelopatia/efeitos dos fármacos , Cassia/efeitos dos fármacos , Hidroxibenzoatos/química , Meristema/citologia , Índice Mitótico , Cebolas/efeitos dos fármacos , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos
16.
Plant Physiol ; 169(1): 748-59, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26232490

RESUMO

To improve seed iron (Fe) content and bioavailability, it is crucial to decipher the mechanisms that control Fe storage during seed development. In Arabidopsis (Arabidopsis thaliana) seeds, most Fe is concentrated in insoluble precipitates, with phytate in the vacuoles of cells surrounding the vasculature of the embryo. NATURAL RESISTANCE ASSOCIATED-MACROPHAGE PROTEIN3 (AtNRAMP3) and AtNRAMP4 function redundantly in Fe retrieval from vacuoles during germination. When germinated under Fe-deficient conditions, development of the nramp3nramp4 double mutant is arrested as a consequence of impaired Fe mobilization. To identify novel genes involved in seed Fe homeostasis, we screened an ethyl methanesulfonate-mutagenized population of nramp3nramp4 seedlings for mutations suppressing their phenotypes on low Fe. Here, we report that, among the suppressors, two independent mutations in the VACUOLAR IRON TRANSPORTER1 (AtVIT1) gene caused the suppressor phenotype. The AtVIT1 transporter is involved in Fe influx into vacuoles of endodermal and bundle sheath cells. This result establishes a functional link between Fe loading in vacuoles by AtVIT1 and its remobilization by AtNRAMP3 and AtNRAMP4. Moreover, analysis of subcellular Fe localization indicates that simultaneous disruption of AtVIT1, AtNRAMP3, and AtNRAMP4 limits Fe accumulation in vacuolar globoids.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Transporte de Cátions/genética , Ferro/metabolismo , Mutação/genética , Vacúolos/metabolismo , Alelos , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Proteínas de Transporte de Cátions/metabolismo , Cotilédone/efeitos dos fármacos , Cotilédone/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Técnicas de Inativação de Genes , Genes de Plantas , Genes Supressores , Germinação/efeitos dos fármacos , Ferro/farmacologia , Modelos Biológicos , Mutagênese , Fenótipo , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Espectrometria por Raios X , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Vacúolos/efeitos dos fármacos
17.
Plant Cell Physiol ; 56(9): 1711-20, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26139237

RESUMO

The enhanced transport capability of transfer cells (TCs) arises from their ingrowth wall architecture comprised of a uniform wall on which wall ingrowths are deposited. The wall ingrowth papillae provide scaffolds to amplify plasma membranes that are enriched in nutrient transporters. Using Vicia faba cotyledons, whose adaxial epidermal cells spontaneously and rapidly (hours) undergo a synchronous TC trans-differentiation upon transfer to culture, has led to the discovery of a cascade of inductive signals orchestrating deposition of ingrowth wall papillae. Auxin-induced ethylene biosynthesis initiates the cascade. This in turn drives a burst in extracellular H2O2 production that triggers uniform wall deposition. Thereafter, a persistent and elevated cytosolic Ca(2+) concentration, resulting from Ca(2+) influx through plasma membrane Ca(2+)-permeable channels, generates a Ca(2+) signal that directs formation of wall ingrowth papillae to specific loci. We now report how these Ca(2+)-permeable channels are regulated using the proportionate responses in cytosolic Ca(2+) concentration as a proxy measure of their transport activity. Culturing cotyledons on various combinations of pharmacological agents allowed the regulatory influence of each upstream signal on Ca(2+) channel activity to be evaluated. The findings demonstrated that Ca(2+)-permeable channel activity was insensitive to auxin, but up-regulated by ethylene through two independent routes. In one route ethylene acts directly on Ca(2+)-permeable channel activity at the transcriptional and post-translational levels, through an ethylene receptor-dependent pathway. The other route is mediated by an ethylene-induced production of extracellular H2O2 which then acts translationally and post-translationally to up-regulate Ca(2+)-permeable channel activity. A model describing the differential regulation of Ca(2+)-permeable channel activity is presented.


Assuntos
Cálcio/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Transdiferenciação Celular/efeitos dos fármacos , Citosol/metabolismo , Etilenos/farmacologia , Peróxido de Hidrogênio/farmacologia , Membrana Celular/efeitos dos fármacos , Citosol/efeitos dos fármacos , Ácidos Indolacéticos/farmacologia , Modelos Biológicos , Células Vegetais/efeitos dos fármacos , Células Vegetais/metabolismo , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Biossíntese de Proteínas/efeitos dos fármacos , Receptores de Superfície Celular/metabolismo , Fatores de Tempo , Transcrição Genética/efeitos dos fármacos , Vicia faba/citologia , Vicia faba/efeitos dos fármacos
18.
Proc Natl Acad Sci U S A ; 112(31): 9781-6, 2015 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-26199419

RESUMO

Rhizobia and arbuscular mycorrhizal fungi produce signals that are perceived by host legume receptors at the plasma membrane and trigger sustained oscillations of the nuclear and perinuclear Ca(2+) concentration (Ca(2+) spiking), which in turn leads to gene expression and downstream symbiotic responses. The activation of Ca(2+) spiking requires the plasma membrane-localized receptor-like kinase Does not Make Infections 2 (DMI2) as well as the nuclear cation channel DMI1. A key enzyme regulating the mevalonate (MVA) pathway, 3-Hydroxy-3-Methylglutaryl CoA Reductase 1 (HMGR1), interacts with DMI2 and is required for the legume-rhizobium symbiosis. Here, we show that HMGR1 is required to initiate Ca(2+) spiking and symbiotic gene expression in Medicago truncatula roots in response to rhizobial and arbuscular mycorrhizal fungal signals. Furthermore, MVA, the direct product of HMGR1 activity, is sufficient to induce nuclear-associated Ca(2+) spiking and symbiotic gene expression in both wild-type plants and dmi2 mutants, but interestingly not in dmi1 mutants. Finally, MVA induced Ca(2+) spiking in Human Embryonic Kidney 293 cells expressing DMI1. This demonstrates that the nuclear cation channel DMI1 is sufficient to support MVA-induced Ca(2+) spiking in this heterologous system.


Assuntos
Redes e Vias Metabólicas , Ácido Mevalônico/metabolismo , Transdução de Sinais , Simbiose , Arabidopsis/genética , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/genética , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Inativação Gênica/efeitos dos fármacos , Células HEK293 , Humanos , Hidroximetilglutaril-CoA Redutases/metabolismo , Medicago truncatula/efeitos dos fármacos , Medicago truncatula/genética , Medicago truncatula/microbiologia , Redes e Vias Metabólicas/efeitos dos fármacos , Ácido Mevalônico/farmacologia , Mutação/genética , Micorrizas/efeitos dos fármacos , Micorrizas/fisiologia , Epiderme Vegetal/citologia , Epiderme Vegetal/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Transdução de Sinais/efeitos dos fármacos , Simbiose/efeitos dos fármacos , Simbiose/genética
19.
Proc Natl Acad Sci U S A ; 112(32): 10044-9, 2015 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-26150490

RESUMO

A fundamental mystery of plant cell biology is the occurrence of "stromules," stroma-filled tubular extensions from plastids (such as chloroplasts) that are universally observed in plants but whose functions are, in effect, completely unknown. One prevalent hypothesis is that stromules exchange signals or metabolites between plastids and other subcellular compartments, and that stromules are induced during stress. Until now, no signaling mechanisms originating within the plastid have been identified that regulate stromule activity, a critical missing link in this hypothesis. Using confocal and superresolution 3D microscopy, we have shown that stromules form in response to light-sensitive redox signals within the chloroplast. Stromule frequency increased during the day or after treatment with chemicals that produce reactive oxygen species specifically in the chloroplast. Silencing expression of the chloroplast NADPH-dependent thioredoxin reductase, a central hub in chloroplast redox signaling pathways, increased chloroplast stromule frequency, whereas silencing expression of nuclear genes related to plastid genome expression and tetrapyrrole biosynthesis had no impact on stromules. Leucoplasts, which are not photosynthetic, also made more stromules in the daytime. Leucoplasts did not respond to the same redox signaling pathway but instead increased stromule formation when exposed to sucrose, a major product of photosynthesis, although sucrose has no impact on chloroplast stromule frequency. Thus, different types of plastids make stromules in response to distinct signals. Finally, isolated chloroplasts could make stromules independently after extraction from the cytoplasm, suggesting that chloroplast-associated factors are sufficient to generate stromules. These discoveries demonstrate that chloroplasts are remarkably autonomous organelles that alter their stromule frequency in reaction to internal signal transduction pathways.


Assuntos
Cloroplastos/metabolismo , Transdução de Sinais , Tabaco/metabolismo , Sequência de Bases , Benzoquinonas/farmacologia , Cloroplastos/ultraestrutura , Ritmo Circadiano/efeitos dos fármacos , Diurona/farmacologia , Inativação Gênica/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Modelos Biológicos , Dados de Sequência Molecular , NADP/metabolismo , Oxirredução/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Filogenia , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sacarose/farmacologia , Tiorredoxina Dissulfeto Redutase/metabolismo , Imagem com Lapso de Tempo , Tabaco/efeitos dos fármacos
20.
PLoS One ; 10(7): e0132841, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26181904

RESUMO

Foodborne diseases are a persistent problem in the United States and worldwide. Fresh produce, especially those used as raw foods like salad vegetables, can be contaminated, causing illness. In this study, we determined the number of rotaviruses adsorbed on produce surfaces using group A porcine rotaviruses and 24 cultivars of leafy vegetables and tomato fruits. We also characterized the physicochemical properties of each produce's outermost surface layer, known as the epicuticle. The number of rotaviruses found on produce surfaces varied among cultivars. Three-dimensional crystalline wax structures on the epicuticular surfaces were found to significantly contribute to the inhibition of viral adsorption to the produce surfaces (p = 0.01). We found significant negative correlations between the number of rotaviruses adsorbed on the epicuticular surfaces and the concentrations of alkanes, fatty acids, and total waxes on the epicuticular surfaces. Partial least square model fitting results suggest that alkanes, ketones, fatty acids, alcohols, contact angle and surface roughness together can explain 60% of the variation in viral adsorption. The results suggest that various fresh produce surface properties need to be collectively considered for efficient sanitation treatments. Up to 10.8% of the originally applied rotaviruses were found on the produce surfaces after three washing treatments, suggesting a potential public health concern regarding rotavirus contamination.


Assuntos
Frutas/efeitos dos fármacos , Epiderme Vegetal/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Rotavirus/efeitos dos fármacos , Ligação Viral/efeitos dos fármacos , Alcanos/farmacologia , Animais , Ácidos Graxos/farmacologia , Doenças Transmitidas por Alimentos/prevenção & controle , Frutas/virologia , Humanos , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/virologia , Epiderme Vegetal/ultraestrutura , Epiderme Vegetal/virologia , Folhas de Planta/virologia , Rotavirus/isolamento & purificação , Rotavirus/fisiologia , Infecções por Rotavirus/prevenção & controle , Suínos , Verduras/efeitos dos fármacos , Verduras/virologia , Ceras/química
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