Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 330
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Ecotoxicol Environ Saf ; 191: 110230, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31982682

RESUMO

The potential for the phytoremediation of halophytes has been widely recognized. However, the effects of salt on Cd accumulation characteristics in different halophytic species, which may also be related to their salt tolerance, are still unclear. This study investigated the effects of salinity on Cd accumulation and distribution in two distinct halophytes, Suaeda glauca (euhalophyte) and Limonium aureum (recretohalophyte). Seedlings of the two species were treated with 0, 3, and 6 mg kg-1 soil Cd in combination with or without 0.3% NaCl in a pot experiment. The amount of Cd within the rhizosphere and plant tissues, plant biomass, and the subcellular distribution and chemical forms of Cd were examined. Results showed that the addition of NaCl significantly increased Cd bioavailability at high Cd levels due to the rhizosphere acidification effect. Meanwhile, salinity differently impacted plant biomass allocation, and enhanced Cd uptake and translocation in both studied halophytes. Excess Cd was excreted from the leaf surface, possibly by salt glands of L. aureum, with the salinity facilitating this process. Majority of the Cd was found within the cell walls and vacuolar compartments of two species. However, S. glauca plants had higher proportions of inactive Cd (extracted by 2% HAc and 0.6 M HCl) and lower proportions of active Cd (extracted by 80% ethanol and water), as opposed to L. aureum, which would better inform S. glauca's higher Cd accumulation. Based on these results, S. glauca seems more applicable for phytomanagement of Cd-contaminated saline soils due to its higher capacity for Cd enrichment and tolerance amplified by NaCl.


Assuntos
Cádmio/farmacocinética , Chenopodiaceae/metabolismo , Plumbaginaceae/metabolismo , Plantas Tolerantes a Sal/metabolismo , Poluentes do Solo/farmacocinética , Biodegradação Ambiental , Biomassa , Folhas de Planta/metabolismo , Rizosfera , Salinidade
2.
Plant Mol Biol ; 102(1-2): 1-17, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31655970

RESUMO

KEY MESSAGE: HbMBF1a was isolated and characterized in H. brevisubulatum, and overexpressed HbMBF1a could enhance the salt tolerance and ABA insensitivity in Arabidopsis thaliana. The transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions. Salinity is an abiotic stress that considerably affects plant growth, yield, and distribution. Hordeum brevisubulatum is a halophyte that evolved to become highly tolerant to salinity. Multiprotein bridging factor 1 (MBF1) is a transcriptional coactivator and an important regulator of stress tolerance. In this study, we isolated and characterized HbMBF1a based on the transcriptome data of H. brevisubulatum grown under saline conditions. We overexpressed HbMBF1a in Arabidopsis thaliana and compared the phenotypes of the transgenic lines and the wild-type in response to stresses. The results indicated that HbMBF1a expression was induced by salt and ABA treatments during the middle and late stages. The overexpression of HbMBF1a in A. thaliana resulted in enhanced salt tolerance and ABA insensitivity. More specifically, the enhanced salt tolerance manifested as the increased seed germination and seedling growth and development. Similarly, under ABA treatments, the cotyledon greening rate and seedling root length were higher in the HbMBF1a-overexpressing lines, suggesting the transgenic plants were better adapted to high exogenous ABA levels. Furthermore, the transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions. Thus, HbMBF1a is a positive regulator of salt and ABA responses, and the corresponding gene may be useful for producing transgenic plants that are salt tolerant and/or ABA insensitive, with few adverse effects. This study involved a comprehensive analysis of HbMBF1a. The results may provide the basis and insight for the application of MBF1 family genes for developing stress-tolerant crops.


Assuntos
Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Hordeum/genética , Hordeum/metabolismo , Plantas Geneticamente Modificadas/genética , Tolerância ao Sal/genética , Plantas Tolerantes a Sal/genética , Transativadores/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cotilédone/metabolismo , Genes de Plantas/genética , Germinação , Fenótipo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , Tolerância ao Sal/fisiologia , Plantas Tolerantes a Sal/metabolismo , Sais/farmacologia , Plântula/crescimento & desenvolvimento , Análise de Sequência de DNA , Estresse Fisiológico/genética , Transativadores/classificação , Transativadores/metabolismo , Transcriptoma , Transformação Genética
3.
BMC Genomics ; 20(1): 990, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31847807

RESUMO

BACKGROUND: Salinity has obvious effects on plant growth and crop productivity. The salinity-responsive mechanisms have been well-studied in differentiated organs (e.g., leaves, roots and stems), but not in unorganized cells such as callus. High-throughput quantitative proteomics approaches have been used to investigate callus development, somatic embryogenesis, organogenesis, and stress response in numbers of plant species. However, they have not been applied to callus from monocotyledonous halophyte alkaligrass (Puccinellia tenuifora). RESULTS: The alkaligrass callus growth, viability and membrane integrity were perturbed by 50 mM and 150 mM NaCl treatments. Callus cells accumulated the proline, soluble sugar and glycine betaine for the maintenance of osmotic homeostasis. Importantly, the activities of ROS scavenging enzymes (e.g., SOD, APX, POD, GPX, MDHAR and GR) and antioxidants (e.g., ASA, DHA and GSH) were induced by salinity. The abundance patterns of 55 salt-responsive proteins indicate that salt signal transduction, cytoskeleton, ROS scavenging, energy supply, gene expression, protein synthesis and processing, as well as other basic metabolic processes were altered in callus to cope with the stress. CONCLUSIONS: The undifferentiated callus exhibited unique salinity-responsive mechanisms for ROS scavenging and energy supply. Activation of the POD pathway and AsA-GSH cycle was universal in callus and differentiated organs, but salinity-induced SOD pathway and salinity-reduced CAT pathway in callus were different from those in leaves and roots. To cope with salinity, callus mainly relied on glycolysis, but not the TCA cycle, for energy supply.


Assuntos
Poaceae/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse Salino , Antioxidantes/metabolismo , Metabolismo Energético/efeitos dos fármacos , Osmorregulação/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Poaceae/efeitos dos fármacos , Poaceae/enzimologia , Poaceae/crescimento & desenvolvimento , Mapeamento de Interação de Proteínas , Proteômica , Salinidade , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/metabolismo , Cloreto de Sódio/toxicidade
4.
BMC Plant Biol ; 19(1): 469, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690290

RESUMO

BACKGROUND: Soybean (Glycine max (L.)) is one the most important oil-yielding cash crops. However, the soybean production has been seriously restricted by salinization. It is therefore crucial to identify salt tolerance-related genes and reveal molecular mechanisms underlying salt tolerance in soybean crops. A better understanding of how plants resist salt stress provides insights in improving existing soybean varieties as well as cultivating novel salt tolerant varieties. In this study, the biological function of GmNHX1, a NHX-like gene, and the molecular basis underlying GmNHX1-mediated salt stress resistance have been revealed. RESULTS: We found that the transcription level of GmNHX1 was up-regulated under salt stress condition in soybean, reaching its peak at 24 h after salt treatment. By employing the virus-induced gene silencing technique (VIGS), we also found that soybean plants became more susceptible to salt stress after silencing GmNHX1 than wild-type and more silenced plants wilted than wild-type under salt treatment. Furthermore, Arabidopsis thaliana expressing GmNHX1 grew taller and generated more rosette leaves under salt stress condition compared to wild-type. Exogenous expression of GmNHX1 resulted in an increase of Na+ transportation to leaves along with a reduction of Na+ absorption in roots, and the consequent maintenance of a high K+/Na+ ratio under salt stress condition. GmNHX1-GFP-transformed onion bulb endothelium cells showed fluorescent pattern in which GFP fluorescence signals enriched in vacuolar membranes. Using the non-invasive micro-test technique (NMT), we found that the Na+ efflux rate of both wild-type and transformed plants after salt treatment were significantly higher than that of before salt treatment. Additionally, the Na+ efflux rate of transformed plants after salt treatment were significantly higher than that of wild-type. Meanwhile, the transcription levels of three osmotic stress-related genes, SKOR, SOS1 and AKT1 were all up-regulated in GmNHX1-expressing plants under salt stress condition. CONCLUSION: Vacuolar membrane-localized GmNHX1 enhances plant salt tolerance through maintaining a high K+/Na+ ratio along with inducing the expression of SKOR, SOS1 and AKT1. Our findings provide molecular insights on the roles of GmNHX1 and similar sodium/hydrogen exchangers in regulating salt tolerance.


Assuntos
Proteínas de Plantas/metabolismo , Tolerância ao Sal/genética , Plantas Tolerantes a Sal/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Soja/metabolismo , Arabidopsis/genética , Inativação Gênica , Proteínas de Plantas/genética , Potássio/metabolismo , Plantas Tolerantes a Sal/genética , Sódio/metabolismo , Trocadores de Sódio-Hidrogênio/genética , Soja/genética , Estresse Fisiológico/genética , Regulação para Cima , Vacúolos/metabolismo
5.
Plant Physiol Biochem ; 143: 83-93, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31491703

RESUMO

Ethylene insensitive 3 (EIN3), a key transcription factor in ethylene signal transduction, play important roles in plant stress signaling pathways. In this study, we isolated and characterized an EIN3-like gene from cotton (Gossypium hirsutum), designated as GhEIN3. GhEIN3 is highly expressed in vegetative tissues, and its expression is induced by 1-aminocyclopropane-1-carboxylic acid (ACC) and NaCl. Ectopic expression of GhEIN3 in Arabidopsis elevated plants' response to ethylene, which exhibit smaller leaves, more root hairs, shorter roots and hypocotyls. The germination rate, survival rate and root length of GhEIN3 transgenic plants were significantly improved compared to wild type under salt stress. GhEIN3 transgenic plants accumulated less H2O2 and malondialdehyde (MDA), while higher superoxide dismutase (SOD) and peroxidase (POD) activities were detected under salt stress. In addition, expression of several genes related to reactive oxygen species (ROS) pathway and ABA signaling pathway was increased in the GhEIN3 transgenic plants under salt stress. In contrast, virus-induced gene silencing (VIGS) of GhEIN3 in cotton enhanced the sensitivity of transgenic plants to salt stress, accumulating higher H2O2 and MDA and lower SOD and POD activities compared to control plants. Collectively, our results revealed that GhEIN3 might be involved in the regulation of plant response to salt stress by regulating ABA and ROS pathway during plant growth and development.


Assuntos
Gossypium/efeitos dos fármacos , Gossypium/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Gossypium/genética , Malondialdeído/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tolerância ao Sal/genética , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/genética , Plantas Tolerantes a Sal/metabolismo , Cloreto de Sódio/farmacologia
6.
Plant Physiol Biochem ; 143: 212-223, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31518852

RESUMO

In this study, we reported on an ASR gene (TtASR) related to salt/drought tolerance from the edible halophyte Tetragonia tetragonoides (Pall.) Kuntze (Aizoaceae). A phylogenetic analysis revealed that TtASR was evolutionarily close to other two halophytic glycine-rich ASR members, SbASR-1 (from Salicornia brachiate) and SlASR (from Suaeda liaotungensis), with a typical abscisic acid (ABA)/water-deficit stress (WDS) domain at C-terminal. Quantitative RT-PCR analyses showed that TtASR was expressed in all tested different organs of the T. tetragonoides plant and that expression levels were apparently induced after salt, osmotic stress, and ABA treatments in T. tetragonoides seedlings. An induction of TtASR improved the growth performance of yeast and bacteria more than the control under high salinity, osmotic stress, and oxidative stress. TtASR was not a nuclear-specific protein in plant, and the transcriptional activation assay also demonstrated that TtASR could not activate reporter gene's expression in yeast. TtASR overexpressed Arabidopsis plants exhibited higher tolerance for salt/drought and oxidative stresses and lower ROS accumulation than wild type (WT) plants, accompanied by increased CAT, SOD activities, higher proline content, and lower MDA content in vivo. The results indicated that the TtASR was involved in plant responses to salt and drought, probably by mediating water homeostasis or by acting as ROS scavengers, and that it decreased the membrane damage and improved cellular osmotic adjustment that respond to abiotic stresses in microorganisms and plants.


Assuntos
Aizoaceae/metabolismo , Glicina/química , Proteínas de Plantas/metabolismo , Ácido Abscísico/metabolismo , Aizoaceae/efeitos dos fármacos , Aizoaceae/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Prolina/metabolismo , Tolerância ao Sal , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/metabolismo , Plantas Tolerantes a Sal/fisiologia , Plântula/efeitos dos fármacos , Plântula/metabolismo , Plântula/fisiologia , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
7.
Plant Cell Physiol ; 60(11): 2423-2435, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31292634

RESUMO

Control of K+ and Na+ transport plays a central role in plant adaptation to salinity. In the halophyte Hordeum maritimum, we have characterized a transporter gene, named HmHKT2;1, whose homolog HvHKT2;1 in cultivated barley, Hordeum vulgare, was known to give rise to increased salt tolerance when overexpressed. The encoded protein is strictly identical in two H. maritimum ecotypes, from two biotopes (Tunisian sebkhas) affected by different levels of salinity. These two ecotypes were found to display distinctive responses to salt stress in terms of biomass production, Na+ contents, K+ contents and K+ absorption efficiency. Electrophysiological analysis of HmHKT2;1 in Xenopus oocytes revealed distinctive properties when compared with HvHKT2;1 and other transporters from the same group, especially a much higher affinity for both Na+ and K+, and an Na+-K+ symporter behavior in a very broad range of Na+ and K+ concentrations, due to reduced K+ blockage of the transport pathway. Domain swapping experiments identified the region including the fifth transmembrane segment and the adjacent extracellular loop as playing a major role in the determination of the affinity for Na+ and the level of K+ blockage in these HKT2;1 transporters. The analysis (quantitative reverse transcription-PCR; qRT-PCR) of HmHKT2;1 expression in the two ecotypes submitted to saline conditions revealed that the levels of HmHKT2;1 transcripts were maintained constant in the most salt-tolerant ecotype whereas they decreased in the less tolerant one. Both the unique functional properties of HmHKT2;1 and the regulation of the expression of the encoding gene could contribute to H. maritimum adaptation to salinity.


Assuntos
Hordeum/metabolismo , Proteínas de Plantas/metabolismo , Animais , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Hordeum/genética , Proteínas de Plantas/genética , Potássio/metabolismo , Plantas Tolerantes a Sal/metabolismo , Sódio/metabolismo , Xenopus
8.
Physiol Plant ; 167(1): 2-4, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31268563

RESUMO

Generating salt-tolerant plants that can cope with increasing soil salinity is a major goal of crop-breeding programs worldwide. Together with genetic approaches, research efforts are focusing on finding chemical modulators of salt tolerance. The exogenous application of 5-aminolevulinic acid (ALA) has been shown to improve salt tolerance in diverse crop species, but its mechanism of action is not properly understood. Wu et al. (2019) report that ALA treatment enhances reactive oxygen species (ROS) production in the roots of salt-stressed strawberry plants. Activation of several key ion transporters downstream to the ROS signal helps to sequester the toxic Na+ ions in the roots and protects the shoots against salt stress.


Assuntos
Ácido Aminolevulínico/metabolismo , Fragaria/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fragaria/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Tolerância ao Sal , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/metabolismo , Cloreto de Sódio/farmacologia
9.
Plant Biol (Stuttg) ; 21(6): 1150-1158, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31273898

RESUMO

Soil degradation resulting from various types of salinity is a major environmental problem, especially in arid and semiarid regions. Exploring the water-related physiological traits of halophytes is useful for understanding the mechanisms of salt tolerance. This knowledge could be used to rehabilitate degraded arid lands. To investigate whether different types of salinity influence the water sources and water-use efficiency of desert plants (Karelinia caspia, Tamarix hohenackeri, Nitraria sibirica, Phragmites australis, Alhagi sparsifolia, Suaeda microphylla, Kalidium foliatum) in natural environments, we measured leaf gas exchange, leaf carbon and xylem oxygen isotope composition and soil oxygen isotope composition at neutral saline-sodic site (NSS) and alkaline saline-sodic site (ASS) in northwest China. The studied plants had different xylem water oxygen isotope compositions (δ18 O) and foliar carbon isotope compositions (δ13 C), indicating that desert plants coexist through differentiation in water use patterns. Compared to that at the NSS site, the stem water in K. caspia, A. sparsifolia and S. microphylla was depleted in 18 O at the ASS site, which indicates that plants can switch to obtain water from deeper soil layers when suffering environmental stress from both salinity and alkalinisation. Alhagi sparsifolia had higher δ13 C at the ASS site than at the NSS site, while K. caspia and S. microphylla had lower δ13 C, which may have resulted from interspecific differences in plant alkali and salt tolerance ability. Our results suggest that under severe salinity and alkalinity, plants may exploit deeper soil water to avoid ion toxicity resulting from high concentrations of soluble salts in the superficial soil layer. In managed lands, it is vital to select and cultivate different salt-tolerant or alkali-tolerant plant species in light of local conditions.


Assuntos
Poaceae/metabolismo , Marcação por Isótopo , Fotossíntese , Folhas de Planta , Salinidade , Plantas Tolerantes a Sal/metabolismo , Solo , Água/metabolismo
10.
J Plant Physiol ; 240: 153005, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31271976

RESUMO

Many areas exhibiting increased concentrations of soluble salts are simultaneously polluted with heavy metals (HM), and halophytes with extended tolerance to heavy metal toxicity seem to represent a promising tool for their phytoremediation. In this study, the response of the soil-grown C3-CAM (Crassulacean acid metabolism) intermediate halophyte Mesembryanthemum crystallinum (common ice plant) to increased concentrations of Cd (0.01-1 mM) was investigated. None of the tested Cd treatments affected growth parameters or tissue water content of either C3 or CAM-performing plants. Chlorophyll a fluorescence confirmed high tolerance of the photosynthetic apparatus of both metabolic states towards Cd. Plants performing both photosynthesis types accumulated significant Cd amounts only under the highest (1 mM) treatment, and the metal was primarily deposited in the roots, which are features typical of an excluding strategy. Upon the application of 1 mM Cd solution CAM-performing plants, due to the NaCl pre-treatment applied for CAM induction, were exposed to significantly higher amounts of bioavailable Cd in comparison with those of C3-performing plants. As a result, roots of CAM plants accumulated over 4-fold higher Cd amounts when compared with C3 plants. In our opinion, enhanced Cd-accumulating potential observed in CAM-performing plants was the effect of osmotic stress episode and resulting modifications e.g. in the detoxifying capacity of the antioxidative system. Increased antioxidative potential of NaCl pre-treated plants was pronounced with significantly higher activity of CuZnSOD (copper-zinc superoxide dismutase), not achievable in C3 plants subjected to high Cd concentrations. Moreover, the applied Cd doses induced SOD activity in a compartment-dependent manner only in C3 plants. We confirmed that none of the applied Cd concentrations initiated the metabolic shift from C3 to CAM.


Assuntos
Cádmio/efeitos adversos , Mesembryanthemum/efeitos dos fármacos , Plantas Tolerantes a Sal/efeitos dos fármacos , Poluentes do Solo/efeitos adversos , Relação Dose-Resposta a Droga , Mesembryanthemum/enzimologia , Mesembryanthemum/crescimento & desenvolvimento , Mesembryanthemum/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/enzimologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/enzimologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/metabolismo , Superóxido Dismutase/metabolismo
11.
Plant Biol (Stuttg) ; 21(6): 1167-1175, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31332917

RESUMO

Coastal salt marsh plants employ various combinations of morphological and physiological adaptations to survive under saline conditions. Little information is available on salinity tolerance mechanisms of Halopeplis perfoliata, a C3 stem succulent halophyte. We investigated the growth, photosynthesis and antioxidant defence mechanisms of H. perfoliata under saline conditions (0, 150, 300 and 600 mM NaCl) in an open greenhouse. Optimal shoot succulence, projected shoot area and relative growth rate were obtained in the low (150 mm NaCl) salinity treatment, while growth was inhibited at the highest salinity (600 mm NaCl). The CO2 compensation point and carbon isotope composition of biomass confirmed C3 photosynthesis. Increases in salinity did not affect the photosynthetic pigment content or maximum quantum efficiency of PSII of H. perfoliata. Assimilation of CO2 (A) also remained unaffected by salinity. A modest effect on some gas exchange and photochemistry parameters was observed at 600 mm NaCl. With increasing salinity, there was a continual increase in respiration, suggesting utilisation of energy to cope with saline conditions. Under 300 and 600 mm NaCl, there was an increase in H2 O2 and MDA with a concomitant rise in AsA, GR content and CAT activity. Hence, H. perfoliata appears to be an obligate halophyte that can grow up to seawater salinities by modulating photosynthetic gas exchange, photochemistry and the antioxidant defence systems.


Assuntos
Amaranthaceae/metabolismo , Amaranthaceae/fisiologia , Antioxidantes/metabolismo , Clorofila/metabolismo , Fotossíntese/fisiologia , Salinidade , Tolerância ao Sal , Plantas Tolerantes a Sal/metabolismo
12.
Ecotoxicol Environ Saf ; 182: 109382, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31255867

RESUMO

Polycyclic aromatic hydrocarbons (PAH) have become a threat for the conservation of wetlands worldwide. The halophyte Spartina densiflora has shown to be potentially useful for soil phenanthrene phytoremediation, but no studies on bacteria-assisted hydrocarbon phytoremediation have been carried out with this halophyte. In this work, three phenanthrene-degrading endophytic bacteria were isolated from S. densiflora tissues and used for plant inoculation. Bacterial bioaugmentation treatments slightly improved S. densiflora growth, photosynthetic and fluorescence parameters. But endophyte-inoculated S. densiflora showed lower soil phenanthrene dissipation rates than non-inoculated S. densiflora (30% below) or even bulk soil (23% less). Our work demonstrates that endophytic inoculation on S. densiflora under greenhouse conditions with the selected PAH-degrading strains did not significantly increase inherent phenanthrene soil dissipation capacity of the halophyte. It would therefore be advisable to provide effective follow-up of bacterial colonization, survival and metabolic activity during phenanthrene soil phytoremediation.


Assuntos
Bactérias/metabolismo , Fenantrenos/análise , Poaceae/metabolismo , Plantas Tolerantes a Sal/metabolismo , Poluentes do Solo/análise , Solo/química , Biodegradação Ambiental , Endófitos/metabolismo , Fotossíntese , Poaceae/microbiologia , Plantas Tolerantes a Sal/microbiologia , Microbiologia do Solo , Áreas Alagadas
13.
Plant Sci ; 285: 14-25, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203878

RESUMO

Intracellular Na+/H+ antiporters (NHXs) play important roles in plant tolerance to salt stress. However, plant NHXs functioning in salt tolerance and the underlying physiological mechanisms remain poorly understood. In this report, we report the identification and functional characterization of PbrNHX2 isolated from Pyrus betulaefolia. PbrNHX2 expression levels were induced by salt, and dehydration, but was unaffected by cold. PbrNHX2 was localized in the tonoplast. Overexpression of PbrNHX2 in tobacco and Pyrus ussuriensis conferred enhanced tolerance to salt tolerance, whereas down-regulation of PbrNHX2 in Pyrus betulaefolia by virus-induced gene silencing (VIGS) resulted in elevated salt sensitivity. The transgenic lines contained lower levels of Na+, higher levels of K+, and higher K/Na ratio, whereas they were changed in an opposite way when PbrNHX2 was silenced. In addition, the transgenic plants accumulated lower levels of reactive oxygen species compared with wild type, accompanied by higher activities of three antioxidant enzymes. Taken together, the data demonstrate that PbrNHX2 plays a positive role in salt tolerance and that it holds a great potential for engineering salt tolerance in crops.


Assuntos
Genes de Plantas/fisiologia , Proteínas de Plantas/metabolismo , Pyrus/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Plantas Tolerantes a Sal/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Inativação Gênica , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Pyrus/genética , Pyrus/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Estresse Salino , Plantas Tolerantes a Sal/genética , Plantas Tolerantes a Sal/fisiologia , Trocadores de Sódio-Hidrogênio/genética , Trocadores de Sódio-Hidrogênio/fisiologia , Tabaco
14.
J Plant Physiol ; 240: 152995, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252320

RESUMO

The SaCLCa1 gene, a putative orthologue of AtCLCa, the Arabidopsis thaliana gene encoding a NO3-/H+ antiporter, was cloned from the halophyte Suaeda altissima. It belonged to the CLC family, comprising anionic channels and anion/H+ antiporters. SaCLCa1 ion specificity was studied by heterologous expression of this gene in Saccharomyces cerevisiae GEF1 disrupted strain, Δgef1, where GEF1 encoded the only CLC family protein, the Cl- transporter Gef1p, in undisrupted strains of this organism. For comparison, the function of another recently identified S. altissima CLC family gene, SaCLCc1, was also characterised. Expression of SaCLCc1 in Δgef1 cells restored their ability to grow on selective media. This supported the chloride specificity of this transporter. By contrast, expression of SaCLCa1 did not complement the growth defect phenotype of Δgef1 cells. However, growth of the Δgef1 mutant on the selective media was partially restored when it was transformed with SaCLCa1(C562 T), encoding the modified protein SaCLCa1(P188S), in which proline responsible for NO3- selectivity in selective filter was replaced by serine providing chloride selectivity. Quantitative real-time polymerase chain reactions (qRT-PCR) showed that significant induction of SaCLCa1 occurred in the roots of S. altissima when plants were grown on nitrate-deficient medium, while SaCLCc1 activation was observed in S. altissima leaves of plants grown in increasing Cl- concentrations of nutrient solution. These results suggested that SaCLCa1 and SaCLCc1 function as anionic transporters with nitrate and chloride specificities, respectively.


Assuntos
Chenopodiaceae/genética , Canais de Cloreto/genética , Proteínas de Plantas/genética , Plantas Tolerantes a Sal/genética , Sequência de Aminoácidos , Sequência de Bases , Chenopodiaceae/metabolismo , Canais de Cloreto/química , Canais de Cloreto/metabolismo , Microrganismos Geneticamente Modificados/genética , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Saccharomyces cerevisiae/genética , Plantas Tolerantes a Sal/metabolismo , Alinhamento de Sequência
15.
Plant Cell Physiol ; 60(8): 1829-1841, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31119292

RESUMO

Alternative oxidase (AOX) has been reported to be involved in mitochondrial function and redox homeostasis, thus playing an essential role in plant growth as well as stress responses. However, its biological functions in nonseed plants have not been well characterized. Here, we report that AOX participates in plant salt tolerance regulation in moss Physcomitrella patens (P. patens). AOX is highly conserved and localizes to mitochondria in P. patens. We observed that PpAOX rescued the impaired cyanide (CN)-resistant alternative (Alt) respiratory pathway in Arabidopsis thaliana (Arabidopsis) aox1a mutant. PpAOX transcription and Alt respiration were induced upon salt stress in P. patens. Using homologous recombination, we generated PpAOX-overexpressing lines (PpAOX OX). PpAOX OX plants exhibited higher Alt respiration and lower total reactive oxygen species accumulation under salt stress condition. Strikingly, we observed that PpAOX OX plants displayed decreased salt tolerance. Overexpression of PpAOX disturbed redox homeostasis in chloroplasts. Meanwhile, chloroplast structure was adversely affected in PpAOX OX plants in contrast to wild-type (WT) P. patens. We found that photosynthetic activity in PpAOX OX plants was also lower compared with that in WT. Together, our work revealed that AOX participates in plant salt tolerance in P. patens and there is a functional link between mitochondria and chloroplast under challenging conditions.


Assuntos
Bryopsida/metabolismo , Cloroplastos/metabolismo , Proteínas Mitocondriais/metabolismo , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Plantas Tolerantes a Sal/metabolismo , Bryopsida/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas Mitocondriais/genética , Oxirredução , Oxirredutases/genética , Proteínas de Plantas/genética , Plantas Tolerantes a Sal/genética
16.
Ecotoxicology ; 28(5): 520-527, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31119593

RESUMO

Halophytes have been considered promising candidates for accumulating heavy metals from saline soils; however, little information has been given on plant physiological responses and heavy metal transportation and accumulation in halophytes that grow in heavy metal-polluted saline soils. This study hypothesized that salinity or heavy metals could induce alterations in plant growth, antioxidant enzyme activities and accumulation and transportation of heavy metals or sodium (Na) in Suaeda salsa. Pot experiments were conducted to test the above hypothesis. Lead (Pb) was selected as the representative heavy metal, and NaCl was added to simulate the Pb-polluted saline soil. The results showed that 0.5% NaCl addition alleviated the inhibition of plant growth under moderate Pb stress (35 and 100 mg kg-1 Pb levels), while the phytotoxicity on plants was magnified by 1.0% NaCl addition. NaCl weakened the oxidative stress in Pb-treated plants by increasing the activity levels of antioxidative enzymes (dismutase (SOD), peroxidase (POD) and catalase (CAT)). At all Pb levels, as the NaCl addition increased, significant increases were observed in the concentration of Na. The 100 mg kg-1 Pb induced a greater increase in Na concentrations than the 35 mg kg-1 Pb did, while the latter induced a greater increase than the 300 mg kg-1 Pb did. NaCl improved Pb translocation factor and its accumulation in Suaeda salsa under Pb stress, indicating that NaCl improves Pb uptake and translocation from roots to shoots and enhances the phytoextraction of Pb. Compared with the 0.1% NaCl treatment, the 0.5 and 1.0% NaCl treatments increased the concentrations of bioavailable Pb in the rhizosphere by 15.0-19.2 and 28.6-35.1%, respectively, indicating the contribution of salinity in producing more available Pb for plant uptake. Moderate salinity may be profitable for Pb transportation and accumulation in plants when there are positive effects on plant growth, antioxidant enzyme activities and Pb availability. These facts suggest that the halophyte Suaeda salsa may be exploited to remediate heavy metal-contaminated saline soils.


Assuntos
Antioxidantes/metabolismo , Chenopodiaceae/efeitos dos fármacos , Estresse Salino/fisiologia , Plantas Tolerantes a Sal/efeitos dos fármacos , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Chenopodiaceae/enzimologia , Chenopodiaceae/crescimento & desenvolvimento , Chenopodiaceae/metabolismo , Chumbo/metabolismo , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/metabolismo , Sódio/metabolismo
17.
Ecotoxicol Environ Saf ; 179: 198-211, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31048216

RESUMO

Among the most intriguing features characterizing extremophile plants is their ability to rapidly recover growth activity upon stress release. Here, we investigated the responses of the halophyte C. maritima to drought and recovery at both physiological and leaf proteome levels. Six week-old plants were either cultivated at 100% or at 25% field capacity. After 12 d of treatment, one lot of dehydrated plants was rewatered to 100% FC for 14 d (stress release). Drought stress impaired shoot hydration, photosynthetic activity and chlorophyll content compared to the control, resulting in severe plant growth restriction. This was concomitant with a marked increase in anthocyanin and proline concentrations. Upon stress release, C. maritima rapidly recovered with respect to all measured parameters. Two-dimensional gel-based proteome analysis of leaves revealed 84 protein spots with significantly changed volumes at the compared conditions: twenty-eight protein spots between normally watered plants and stressed plants but even 70 proteins between stressed and recovered plants. Proteins with higher abundance induced upon rewatering were mostly involved in photosynthesis, glycolytic pathway, TCA cycle, protein biosynthesis, and other metabolic pathways. Overall, C. maritima likely adopts a drought-avoidance strategy, involving efficient mechanisms specifically taking place upon stress release, leading to fast and strong recovery.


Assuntos
Brassicaceae/metabolismo , Secas , Folhas de Planta/metabolismo , Proteoma/metabolismo , Plantas Tolerantes a Sal/metabolismo , Estresse Fisiológico , Clorofila/metabolismo , Fotossíntese/fisiologia , Prolina/metabolismo , Tunísia , Água/metabolismo
18.
Ecotoxicol Environ Saf ; 180: 12-22, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31059903

RESUMO

The study aimed at comparing metabolic reactions of a halophyte Aster tripolium to abiotic stresses. Profiling of endogenous phytohormones, soluble carbohydrates and stress-related amino acids was conducted in plants exposed to moderate and high salinity (150 and 300 mM NaCl), and heavy metal salts CdCl2 or PbCl2 (100 and 200 µM). High NaCl and Pb doses inhibited growth of A. tripolium (Stress Tolerance Index STI) of 37% and 32-35%, respectively. The plants tolerated moderate salinity and Cd (STI = 91% and STI = 83-96%, respectively). Toxic metals accumulated mainly in the roots but Cd translocation to the shoots was also observed. The stressors did not affect total concentrations of the main growth promoting phytohormones but we observed enhanced deactivation of auxins and gibberellins, and reduced accumulation of jasmonate precursor. ABA content increased under stress except for moderate salinity. A common reaction was also activation of osmotic adjustment, however it was disparately manifested under salinity and metallic stress. The distinct responses to salinity and metallic stresses involved changes in carbohydrate profile and altered interplay between salicylic acid content and the pool of active gibberellins. The content of active jasmonates diversified A. tripolium reactions to salt excess and each of the heavy metals. This parameter was linked to the accumulation of ethylene precursor. The results of the study can be used to decipher potential co-tolerance mechanism of this halophyte species to multiple environmental stresses.


Assuntos
Aster/efeitos dos fármacos , Metais Pesados/toxicidade , Reguladores de Crescimento de Planta/metabolismo , Plantas Tolerantes a Sal/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Aster/metabolismo , Osmose , Salinidade , Plantas Tolerantes a Sal/metabolismo
19.
Physiol Plant ; 167(1): 5-20, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30891756

RESUMO

To explore the mechanisms of 5-aminolevulinic acid (ALA)-improved plant salt tolerance, strawberries (Fragaria × ananassa Duch. cv. 'Benihoppe') were treated with 10 mg l-1 ALA under 100 mmol l-1 NaCl stress. We found that the amount of Na+ increased in the roots but decreased in the leaves. Laser scanning confocal microscopy (LSCM) observations showed that ALA-induced roots had more Na+ accumulation than NaCl alone. Measurement of the xylem sap revealed that ALA repressed Na+ concentrations to a large extent. The electron microprobe X-ray assay also confirmed ALA-induced Na+ retention in roots. qRT-PCR showed that ALA upregulated the gene expressions of SOS1 (encoding a plasma membrane Na+ /H+ antiporter), NHX1 (encoding a vacuolar Na+ /H+ antiporter) and HKT1 (encoding a protein of high-affinity K+ uptake), which are associated with Na+ exclusion in the roots, Na+ sequestration in vacuoles and Na+ unloading from the xylem vessels to the parenchyma cells, respectively. Furthermore, we found that ALA treatment reduced the H2 O2 content in the leaves but increased it in the roots. The exogenous H2 O2 promoted plant growth, increased root Na+ retention and stimulated the gene expressions of NHX1, SOS1 and HKT1. Diphenyleneiodonium (DPI), an inhibitor of H2 O2 generation, suppressed the effects of ALA or H2 O2 on Na+ retention, gene expressions and salt tolerance. Therefore, we propose that ALA induces H2 O2 accumulation in roots, which mediates Na+ transporter gene expression and more Na+ retention in roots, thereby improving plant salt tolerance.


Assuntos
Ácido Aminolevulínico/farmacologia , Fragaria/efeitos dos fármacos , Fragaria/metabolismo , Peróxido de Hidrogênio/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Sódio/farmacologia , Tolerância ao Sal , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/metabolismo
20.
Plant Physiol Biochem ; 139: 161-170, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30897507

RESUMO

Soil salinization is a major abiotic stress condition that affects about half of global agricultural lands. Salinity leads to osmotic shock, ionic imbalance and/or toxicity and build-up of reactive oxygen species. Na⁺/H⁺ antiporters (NHXs) are integral membrane transporters that catalyze the electro-neutral exchange of K⁺/Na⁺ for H⁺ and are implicated in cell expansion, development, pH/ion homeostasis and salt tolerance. Porteresia coarctata is a salt secreting halophytic wild rice that thrives in the coastal-riverine interface. P. coarctata NHX1 (PcNHXI) expression is induced by salinity in P. coarctata roots and shows high sequence identity to Oryza sativa NHX1. PcNHX1 confers hygromycin and Li+ sensitivity and Na+ tolerance transport in a yeast strain lacking sodium transport systems. Additionally, transgenic PcNHX1 expressing tobacco seedlings (PcNHX1 promoter) show significant growth advantage under increasing concentrations of NaCl and MS salts. Etiolated PcNHX1 seedlings also exhibit significantly elongated hypocotyl lengths in 100 mM NaCl. PcNHX1 expression in transgenic tobacco roots increases under salinity, similar to expression in P. coarctata roots. Under incremental salinity, transgenic lines show reduction in leaf Na+, stem specific accumulation of Na+ and K+ (unaltered Na+/K+ ratios). PcNHX1 transgenic plants also show enhanced chlorophyll content and reduced malondialdehyde (MDA) production in leaves under salinity. The above data suggests that PcNHX1 overexpression (controlled by PcNHX1p) enhances stem specific accumulation of Na+, thereby protecting leaf tissues from salt induced injury.


Assuntos
Hipocótilo/crescimento & desenvolvimento , Proteínas de Plantas/genética , Caules de Planta/metabolismo , Poaceae/genética , Trocadores de Sódio-Hidrogênio/genética , Sódio/metabolismo , Clorofila/metabolismo , Genes de Plantas/genética , Genes de Plantas/fisiologia , Malondialdeído/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Poaceae/fisiologia , Regiões Promotoras Genéticas/genética , Regiões Promotoras Genéticas/fisiologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Plantas Tolerantes a Sal/genética , Plantas Tolerantes a Sal/metabolismo , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Trocadores de Sódio-Hidrogênio/fisiologia , Tabaco
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA