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Enrique Correal - One of the best experts on this subject based on the ideXlab platform.
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Osmolyte concentrations in Atriplex Halimus L. and Atriplex canescens (Pursh) Nutt. adapted to salinity and low temperature (Chenopodiaceae) Resumen
2020Co-Authors: Miloud Aouissat, David J Walker, Kheiria Hcini, Moulay Belkhodja, Enrique CorrealAbstract:Concentración de osmolitos en Atriplex Halimus L. y Atriplex canescens (Pursh) Nutt. adaptados a salinidad y bajas temperaturas (Chenopodiaceae) En este trabajo hemos investigado los efectos de la tolerancia a la congelación de Atriplex Halimus y Atriplex canescens de diferentes poblaciones de Argelia. La tolerancia al frío se determinó mediante ensayos de pérdida de electrolitos en hojas de plantas que crecieron durante tres meses en maceta más un mes de aclimatación al frío. Para A. Halimus se determinó el efecto que producía el incremento de salinidad en el suelo sobre la tolerancia al frío, comparando los niveles de cationes y osmolitos orgánicos en hojas de plantas que crecieron en soluciones salinas, con los de plantas que únicamente habían sido aclimatadas al frío. Se encontró una relación significativa entre la tolerancia al frío y la concentración de Na y Na + K en tejidos. Se relacionan los cambios en la concentración de osmolitos bajo condiciones de salinidad (cultivo hidropónico) con los cambios producidos mediante la interación de aclimatación al frío más salinidad del suelo. Palabras clave: Atriplex Halimus, Atriplex canescens, Cationes, Halofitos, Salinidad, Solutos compatibles, Tolerancia al frío. Abstract We investigated the effects of cold (freezing) tolerance for Atriplex Halimus and Atriplex canescens (Chenopodiaceae) from different locations in Algeria. Plants were grown in pots of soil for three months, after a one-month acclimation period, the cold tolerance was determined, in leaf electrolyte leakage assays. For A. Halimus, the effect of increased soil salinity (addition of NaCl) on tolerance was determined and the cold-acclimated plants were compared with those grown in saline nutrient solution, in relation to leaf levels of cations and organic osmolytes. There was significant correlation between the cold tolerance and the leaf tissue water concentrations of Na and Na+K. Here we relate changes in osmolyte concentration under cold acclimation/soil salinisation
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Atriplex Halimus l its biology and uses
Journal of Arid Environments, 2014Co-Authors: David J Walker, Stanley Lutts, M Sanchezgarcia, Enrique CorrealAbstract:Atriplex Halimus L. (Amaranthaceae) (Mediterranean saltbush) is a halophytic shrub that is widely distributed in arid and semi-arid regions around the Mediterranean basin and east to Saudi Arabia, at elevations less than 900 m. It grows on a variety of soils, from fine to coarse texture, with varying degrees of salinity. There are two sub-species of A. Halimus: Halimus is diploid (2n = 2x = 18) and is found at semi-arid, less-saline sites, while schweinfurthii is tetraploid (2n = 4x = 36) and occupies arid, saline sites. Throughout its distribution, A. Halimus is exposed to high light intensity and temperature and varying degrees of drought and salinity; it can also withstand sub-zero winter temperatures or soil contamination by trace elements. Some of its physiological and biochemical tolerance mechanisms - such as adjustment of plant water relations - are common to all or several of these environmental stresses, but others are specific to particular stresses. The importance of A. Halimus in the functioning of ecosystems is reflected in its promotion of soil biota, while it also acts as a food plant for mammals and arthropods. Its deep root system decreases soil erosion in arid zones, due to stabilisation of the soil. The protein-rich shoot material of A. Halimus makes it an important fodder species for livestock, particularly sheep and goats. However, its low energy value means that it should be supplemented with carbohydrate-rich material, such as cereal straw. Potential new uses of this versatile plant species include the phytoremediation of soils contaminated by trace elements and the exploitation of its biomass as a source of renewable energy. Such applications, together with its continued use in low-intensity farming systems, should ensure that A. Halimus remains a vital plant species in low-rainfall regions. © 2013 Elsevier Ltd. All rights reserved.
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chloride salinity reduces cadmium accumulation by the mediterranean halophyte species Atriplex Halimus l
Environmental and Experimental Botany, 2009Co-Authors: Isabelle S Lefevre, Enrique Correal, Geoffrey Marchal, Pierre Jacques Meerts, Stanley LuttsAbstract:Soil salinity usually increases bioavailability of Cd on heavy metal polluted soils but its impact on Cd absorption and accumulation by plants remains largely unknown. Plants from the halophyte species Atriplex Halimus were therefore exposed for 12 and 14 days to nutrient solution containing 50 mu M CdCl2 in the presence of NaCl, KCl or NaNO3 50 mM. Most Cd present in solution remained as Cd-EDTA and salinity had no impact on Cd speciation. Chloride salinity (NaCl and KCl) reduced Cd accumulation in shoots and roots while NaNO3 increased Cd accumulation in leaves. More than 30% of accumulated Cd was found at the leaf surface and accumulated in trichomes but all tested salts decreased the proportion of excreted Cd. Cadmium induced a decrease in the leaf water content. External NaCl and KCl mitigated the deleterious impact of Cd by inducing osmotic adjustment while NaNO3 and synthesis of protecting compounds such as soluble sugars and glycinebetaine. Free polyamines (putrescine, spermidine and spermine) increased in response to Cd, Cd + NaCl and Cd + KCl while only putrescine increased in response to Cd + NaNO3 center dot Proline exhibited maximal concentration in the leaves of Cd + NaCl and Cd + KCl-treated plants and was correlated with osmotic adjustment. Our results suggest that chloride salinity improved the resistance of A. Halimus to Cd toxicity both by decreasing the absorption of heavy metal and by improving tissular tolerance through an increase in the synthesis of osmoprotective compounds. (C) 2008 Elsevier B.V. All rights reserved.
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seasonal changes in cold tolerance water relations and accumulation of cations and compatible solutes in Atriplex Halimus l
Environmental and Experimental Botany, 2008Co-Authors: David J Walker, Pascual Romero, Aranzazu De Hoyos, Enrique CorrealAbstract:Abstract We determined the cold (freezing) tolerance for field-grown plants of Atriplex Halimus L. (Chenopodiaceae) in relation to plant ploidy level, leaf water relations and accumulation of osmolytes. Plants were grown at two sites in Murcia (Spain), having average minimum temperatures in the coldest month of 0.6 and 12.1 °C, respectively. LT 50 values derived from laboratory freezing tests, using leaves taken from the plants in early winter and in spring, showed greater tolerance for winter-harvested leaves; the acclimation was more pronounced at the cold-winter site. Cold tolerance was related positively with leaf K and/or Na accumulation. Analysis of compatible organic solutes (soluble sugars, total amino acids and quaternary ammonium compounds) showed that cold tolerance (measured both as LT 50 and as winter freezing damage in situ ) was related most closely with leaf concentrations of soluble sugars. The leaf percentage dry matter content was related to both in vitro and in vivo tolerance, while tolerance in vitro was correlated also with the osmotic (potential ψ s ) and the relative water content. The two diploid (2 n = 2 x = 18) populations, from Spain, showed greater cold tolerance than the three tetraploid (2 n = 4 x = 36) populations, from North Africa and Syria, which may be related to the latter's greater cell size and consequent dilution of osmolytes. In this halophytic species, cold tolerance, like salinity and drought tolerance, seems to depend on osmotic adjustment, driven by vacuolar accumulation of K and Na and cytoplasmic accumulation of compatible solutes.
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Determination of Ploidy Level and Nuclear DNA Content in Tunisian Populations of Atriplex Halimus L.
Genetic Resources and Crop Evolution, 2006Co-Authors: Kheiria Hcini, David J Walker, Elena Gonzalez, Nora Frayssinet, Sadok Bouzid, Enrique CorrealAbstract:Atriplex Halimus L. (Chenopodiaceae) (Saltbush) is a perennial species used as a fodder shrub for livestock in arid and semi-arid areas, particularly in North Africa. The aim of this work was to determine whether differences in ploidy level and/or nuclear DNA content exist among populations from widely-separated sites in Tunisia. We determined nuclear DNA content and chromosome numbers for populations of A. Halimus from seven different locations (Gabes, Medenine, Tataouine, Monastir, Tunis, Sidi Bouzid, Kairouan). The chromosome counts showed that all the Tunisian populations, plus a population from Eraclea (Italy), were tetraploid (2 n = 4 x = 36) whereas a population from Cala Tarida (Spain) was diploid (2 n = 2 x = 18). With respect to nuclear DNA, the 2C DNA content of population Cala Tarida was estimated to be 2.41 pg. There was no significant difference among the tetraploid populations (or among plants within populations), whose 2C DNA content ranged from 4.92 to 4.97 pg.
David J Walker - One of the best experts on this subject based on the ideXlab platform.
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Osmolyte concentrations in Atriplex Halimus L. and Atriplex canescens (Pursh) Nutt. adapted to salinity and low temperature (Chenopodiaceae) Resumen
2020Co-Authors: Miloud Aouissat, David J Walker, Kheiria Hcini, Moulay Belkhodja, Enrique CorrealAbstract:Concentración de osmolitos en Atriplex Halimus L. y Atriplex canescens (Pursh) Nutt. adaptados a salinidad y bajas temperaturas (Chenopodiaceae) En este trabajo hemos investigado los efectos de la tolerancia a la congelación de Atriplex Halimus y Atriplex canescens de diferentes poblaciones de Argelia. La tolerancia al frío se determinó mediante ensayos de pérdida de electrolitos en hojas de plantas que crecieron durante tres meses en maceta más un mes de aclimatación al frío. Para A. Halimus se determinó el efecto que producía el incremento de salinidad en el suelo sobre la tolerancia al frío, comparando los niveles de cationes y osmolitos orgánicos en hojas de plantas que crecieron en soluciones salinas, con los de plantas que únicamente habían sido aclimatadas al frío. Se encontró una relación significativa entre la tolerancia al frío y la concentración de Na y Na + K en tejidos. Se relacionan los cambios en la concentración de osmolitos bajo condiciones de salinidad (cultivo hidropónico) con los cambios producidos mediante la interación de aclimatación al frío más salinidad del suelo. Palabras clave: Atriplex Halimus, Atriplex canescens, Cationes, Halofitos, Salinidad, Solutos compatibles, Tolerancia al frío. Abstract We investigated the effects of cold (freezing) tolerance for Atriplex Halimus and Atriplex canescens (Chenopodiaceae) from different locations in Algeria. Plants were grown in pots of soil for three months, after a one-month acclimation period, the cold tolerance was determined, in leaf electrolyte leakage assays. For A. Halimus, the effect of increased soil salinity (addition of NaCl) on tolerance was determined and the cold-acclimated plants were compared with those grown in saline nutrient solution, in relation to leaf levels of cations and organic osmolytes. There was significant correlation between the cold tolerance and the leaf tissue water concentrations of Na and Na+K. Here we relate changes in osmolyte concentration under cold acclimation/soil salinisation
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the tolerance of Atriplex Halimus l to environmental stresses
Emirates Journal of Food and Agriculture, 2014Co-Authors: David J Walker, Stanley LuttsAbstract:Atriplex Halimus L. (Amaranthaceae) (Mediterranean Saltbush) is a perennial, halophytic shrub that possesses the C4 photosynthetic anatomy and physiology. It grows under semi-arid and arid conditions (annual rainfall < 600 mm) from Macaronesia, through the Mediterranean basin countries and into western Asia, being particularly common on saline and degraded soils. Many studies have shed light on the physiological and biochemical mechanisms that, together with the morphological and anatomical features of this species, contribute to its notable tolerance of important abiotic stresses: salinity, drought, extreme temperatures and soil contamination by trace elements. These will be discussed here, highlighting their shared and distinct features. Certain processes are common to two or more stress responses: for example, vacuolar accumulation of sodium and the cytoplasmic accumulation of compatible osmolytes - part of the process of osmotic adjustment - are vital components of the adaptation to drought, salinity and cold. Others, such as oxalate accumulation upon trace elements exposure, seem to be stress-specific, while leaf surface vesiculated hairs (trichomes) and abscisic acid have distinct functions according to the stress. The relevance of these mechanisms to the use of A. Halimus in soil remediation and as livestock forage is discussed.
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Atriplex Halimus l its biology and uses
Journal of Arid Environments, 2014Co-Authors: David J Walker, Stanley Lutts, M Sanchezgarcia, Enrique CorrealAbstract:Atriplex Halimus L. (Amaranthaceae) (Mediterranean saltbush) is a halophytic shrub that is widely distributed in arid and semi-arid regions around the Mediterranean basin and east to Saudi Arabia, at elevations less than 900 m. It grows on a variety of soils, from fine to coarse texture, with varying degrees of salinity. There are two sub-species of A. Halimus: Halimus is diploid (2n = 2x = 18) and is found at semi-arid, less-saline sites, while schweinfurthii is tetraploid (2n = 4x = 36) and occupies arid, saline sites. Throughout its distribution, A. Halimus is exposed to high light intensity and temperature and varying degrees of drought and salinity; it can also withstand sub-zero winter temperatures or soil contamination by trace elements. Some of its physiological and biochemical tolerance mechanisms - such as adjustment of plant water relations - are common to all or several of these environmental stresses, but others are specific to particular stresses. The importance of A. Halimus in the functioning of ecosystems is reflected in its promotion of soil biota, while it also acts as a food plant for mammals and arthropods. Its deep root system decreases soil erosion in arid zones, due to stabilisation of the soil. The protein-rich shoot material of A. Halimus makes it an important fodder species for livestock, particularly sheep and goats. However, its low energy value means that it should be supplemented with carbohydrate-rich material, such as cereal straw. Potential new uses of this versatile plant species include the phytoremediation of soils contaminated by trace elements and the exploitation of its biomass as a source of renewable energy. Such applications, together with its continued use in low-intensity farming systems, should ensure that A. Halimus remains a vital plant species in low-rainfall regions. © 2013 Elsevier Ltd. All rights reserved.
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the effects of soil amendments on the growth of Atriplex Halimus and bituminaria bituminosa in heavy metal contaminated soils
Water Air and Soil Pollution, 2012Co-Authors: Domingo Martinezfernandez, David J WalkerAbstract:In Southern Spain, as in other semi-arid zones, plants used for the phytoremediation of heavy metal-contaminated sites must be able to withstand not only the challenging soil conditions but also seasonal drought and high temperatures. A pot assay was carried out to determine the ability of soil amendments to promote the survival and growth of the seedlings of two native species, Atriplex Halimus L. (Amaranthaceae) and Bituminaria bituminosa (L.) C.H. Stirton (Fabaceae), in two heavy metal-contaminated soils, one of which also had a high level of arsenic (As). Restriction of A. Halimus shoot growth in the non-amended soils appeared to be due to deficiency of nitrogen, phosphorus (P) and potassium (K) and in the more highly contaminated soil to lead (Pb) toxicity. Shoot biomass of A. Halimus in the more highly contaminated soil was increased significantly by compost addition, due to increased uptake of K and P and decreased tissue Pb. The lack of effect of compost on B. bituminosa growth in this soil, despite a large increase in tissue K, may have been due to elevated tissue levels of As and Pb and the high soil salinity. The combination of A. Halimus and compost addition seems appropriate for the phytostabilisation of contaminated semi-arid sites.
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osmolyte concentrations in Atriplex Halimus l and Atriplex canescens pursh nutt adapted to salinity and low temperature chenopodiaceae
Gaceta Sanitaria, 2011Co-Authors: Miloud Aouissat, David J Walker, Kheiria Hcini, Moulay Belkhodja, Enrique Correal CastellanosAbstract:We investigated the effects of cold (freezing) tolerance for Atriplex Halimus and Atriplex canescens (Chenopodiaceae) from different locations in Algeria. Plants were grown in pots of soil for three months, after a one-month acclimation period, the cold tolerance was determined, in leaf electrolyte leakage assays. For A. Halimus, the effect of increased soil salinity (addition of NaCl) on tolerance was determined and the cold-acclimated plants were compared with those grown in saline nutrient solution, in relation to leaf levels of cations and organic osmolytes. There was significant correlation between the cold tolerance and the leaf tissue water concentrations of Na and Na+K. Here we relate changes in osmolyte concentration under cold acclimation/soil sa
Stanley Lutts - One of the best experts on this subject based on the ideXlab platform.
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chloride salinity reduces cadmium accumulation by the mediterranean halophyte species Atriplex Halimus l
Environmental and Experimental Botany, 2009Co-Authors: Isabelle S Lefevre, Enrique Correal, Geoffrey Marchal, Pierre Jacques Meerts, Stanley LuttsAbstract:Soil salinity usually increases bioavailability of Cd on heavy metal polluted soils but its impact on Cd absorption and accumulation by plants remains largely unknown. Plants from the halophyte species Atriplex Halimus were therefore exposed for 12 and 14 days to nutrient solution containing 50 mu M CdCl2 in the presence of NaCl, KCl or NaNO3 50 mM. Most Cd present in solution remained as Cd-EDTA and salinity had no impact on Cd speciation. Chloride salinity (NaCl and KCl) reduced Cd accumulation in shoots and roots while NaNO3 increased Cd accumulation in leaves. More than 30% of accumulated Cd was found at the leaf surface and accumulated in trichomes but all tested salts decreased the proportion of excreted Cd. Cadmium induced a decrease in the leaf water content. External NaCl and KCl mitigated the deleterious impact of Cd by inducing osmotic adjustment while NaNO3 and synthesis of protecting compounds such as soluble sugars and glycinebetaine. Free polyamines (putrescine, spermidine and spermine) increased in response to Cd, Cd + NaCl and Cd + KCl while only putrescine increased in response to Cd + NaNO3 center dot Proline exhibited maximal concentration in the leaves of Cd + NaCl and Cd + KCl-treated plants and was correlated with osmotic adjustment. Our results suggest that chloride salinity improved the resistance of A. Halimus to Cd toxicity both by decreasing the absorption of heavy metal and by improving tissular tolerance through an increase in the synthesis of osmoprotective compounds. (C) 2008 Elsevier B.V. All rights reserved.
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nacl alleviates polyethylene glycol induced water stress in the halophyte species Atriplex Halimus l
Journal of Experimental Botany, 2005Co-Authors: Juanpablo Martinez, Mohammed Bajji, Jeanmarie Kinet, Stanley LuttsAbstract:Atriplex Halimus L. is a C4 xero-halophyte species well adapted to salt and drought conditions. To collect information on the physiological impact of low salt levels on their water-stress resistance, seedlings were exposed for 6 d to nutrient solution containing either 0% or 15% polyethylene glycol 10,000 (PEG), in the presence or in the absence of 50 mM NaCl. Similar experiments were performed with one PEG-resistant and one PEG-sensitive selected cell line exposed for 50 d to 0% or 15% PEG on standard Linsmaier and Skoog (LS) medium, on LS medium supplemented with 50 mM NaCl, or on Na+-free medium. NaCl mitigated the deleterious impact of PEG on growth of both whole plants and PEG-sensitive cell lines and improved the ability of stressed tissues to perform osmotic adjustment (OA). Water stress reduced CO2 net assimilation rates quantified in the presence of high CO2 and low O2 levels (A), stomatal conductance and transpiration, but NaCl improved water use efficiency of PEG-treated plants through its positive effect on A values, especially in young leaves. PEG increased the internal Na+ concentration. The resistant cell line accumulated higher concentration of Na+ than the PEG-sensitive one. The complete absence of Na+ in the medium endangered the survival of both cell lines exposed to PEG. Although Na+ by itself contributed only for a small part to OA, NaCl induced an increase in proline concentration and stimulated the synthesis of glycinebetaine in response to PEG in photosynthetic tissues. Soluble sugars were the main contributors to OA and increased when tissues were simultaneously exposed to PEG and NaCl compared with PEG alone, suggesting that Na+ may influence sugar synthesis and/or translocation.
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osmotic and ionic effects of nacl on germination early seedling growth and ion content of Atriplex Halimus chenopodiaceae
Botany, 2002Co-Authors: Mohammed Bajji, Jeanmarie Kinet, Stanley LuttsAbstract:The effects of salt and osmotic stresses on the germination processes in seeds of the perennial halophyte species Atriplex Halimus L. were compared using iso-osmotic concentrations of NaCl and mannitol. The lowest stress intensity delayed germination, while higher doses of NaCl and mannitol reduced final germination percentages. No significant difference occurred between the effects of these solutes on germination percentages or seedling dry weights. At an external osmotic potential of -0.7 MPa, however, the water content of mannitol-treated seedlings was reduced compared to that of seedlings that developed from NaCl-exposed seeds. The K, Mg, and Pi content decreased in seedlings that developed from mannitol-treated seeds while calcium concentration was strongly reduced in those arising from NaCl-treated seeds. Inhibited seeds were able to germinate at levels similar to those of the control after rinsing in deionized water and imbibition in control conditions. Seedlings produced from NaCl pre-treated seeds had a lower Ca and a higher Na content than control seedlings. The effect of salinity on the germination phase of development is mainly due to its osmotic component, and inhibition of germination is reversible. Both salt and osmotic stresses may have an impact on the mobilization of minerals from the seeds to the young seedling, but this effect does not have any consequence on growth processes analysed on a short-term basis.
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salt stress effects on roots and leaves of Atriplex Halimus l and their corresponding callus cultures
Plant Science, 1998Co-Authors: Mohammed Bajji, Jeanmarie Kinet, Stanley LuttsAbstract:Salt stress effects on growth, osmotic adjustment, mineral and organic contents and soluble peroxidase activities were determined in roots and leaves of Atriplex Halimus and their corresponding callus cultures. Low NaCl doses (150 mM) promoted shoot growth, corroborating the halophilic nature of this species; in these stress conditions, Na+ concentration markedly increased in the leaves indicating that salinity resistance was not associated with the ability of the plants to restrict sodium accumulation in the aerial part. Whole organs and their corresponding calli were able to cope with high NaCl doses but there was no clear correspondence between the physiological behaviour of cell culture and whole plant. For several physiological parameters (osmotic potential (Psi s), mineral content, proline accumulation), roots were less affected by NaCl than leaves while both root and leaf calli behaved in the same way in response to salinity. NaCl-induced modifications of the recorded parameters are discussed in relation to the mechanisms of salinity resistance in this species. Evidence indicated the existence of a cellular basis for salinity resistance in A. Halimus, but the expression of this cellular property at organ level appeared to be masked by the physiological complexity of the intact plant and the nature of the whole organ response was apparently determined primarily by regulation mechanisms assigned by the differentiated tissue organisation. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.
Gaber M. Abogadallah - One of the best experts on this subject based on the ideXlab platform.
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Developmental acquisition of salt tolerance in the halophyte Atriplex Halimus L. is related to differential regulation of salt inducible genes
Plant Growth Regulation, 2014Co-Authors: Reham M. Nada, Gaber M. AbogadallahAbstract:The present study investigated the developmental tolerance of Atriplex Halimus to osmotic and/or ionic stress. A. Halimus was exposed to NaCl (0, 100, 250 and 400 mM), KCl (0, 100, 250 and 400 mM) and sorbitol (0, 200, 500 and 800 mM) at the level of germination, seedling emergence and vegetative stages. The response of A. Halimus to different salts was stage dependent especially to NaCl that had a remarkable effect on A. Halimus growth at each stage. At the germination stage, the growth reduction could be attributed to osmotic effect and HRD may have a role in that osmotic sensitivity. At this stage, the accumulation of Na+ into vacuole could be a strategy for alleviating the osmotic effect. At the seedling emergence stage, the inhibition of growth could be mainly attributed to the ionic effect that may have resulted from excessive accumulation of Na+ along with inconsistent regulations of Na+ manipulating genes. A. Halimus at the vegetative stage was an obligate halophyte with regulated mechanisms of tolerance to both ionic and osmotic components of salt stress. A. Halimus exhibits glycophytic features at the early growth stages but it is an obligate halophyte at the vegetative stage.
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A DREB gene from the xero-halophyte Atriplex Halimus is induced by osmotic but not ionic stress and shows distinct differences from glycophytic homologues
Plant Cell Tissue and Organ Culture (PCTOC), 2011Co-Authors: Abdel Hamid A. Khedr, Reham M. Nada, Mamdouh S. Serag, Mamdouh M. Nemat-alla, Amina Z. Abo-elnaga, W. Paul Quick, Gaber M. AbogadallahAbstract:Studying the regulation of stress inducible genes can lead to understanding of the mechanisms by which halophytes maintain growth and thrive under abiotic stress. Verifying whether ionic or osmotic components of salt stress control the regulation of Dehydration Responsive Element- binding transcription factor ( DREB ) was investigated in the present study. DREB belongs to AP2/EREB group that is induced under abiotic stress and regulates many stress inducible genes that contain DRE binding sites in their promoters. DREB in Atriplex Halimus was regulated by the osmotic component but not by the ionic one of salt stress. It seemed that DREB was not involved in the regulation of sodium manipulating genes like NHX1 , SOS1 or H ^+- PPase . Moreover, DREB could be involved directly of indirectly in CMO regulation because of timing of induction. Also, DREB was the most upregulated gene under salt (fivefold) and drought (twofold) conditions, which reinforced the importance of this gene in A. Halimus tolerance to stress. Moreover, its constitutive expression under normal conditions also indicated its involvement in other growth and developmental programs. The tolerance of A. Halimus and of halophytes, in general, could be attributed to the constitutive expression of its genes and differences in protein structures between halophytes and glycophytes.
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growth stimulation and inhibition by salt in relation to na manipulating genes in xero halophyte Atriplex Halimus l
Acta Physiologiae Plantarum, 2011Co-Authors: Abdel Hamid A. Khedr, Reham M. Nada, Mamdouh S. Serag, Mamdouh M Nematalla, Amina Abo Z Elnaga, Paul W Quick, Gaber M. AbogadallahAbstract:In the present study, Na+ manipulating genes could contribute not only to ion homeostasis but also to growth stimulation with exposing the halophyte Atriplex Halimus L. to moderate NaCl concentration. The stimulation of growth was attributed to Na+ accumulation inside the vacuole leading to increase leaf cell size as well as accelerate leaf cell division. Increasing the assimilatory surface could result in enhancing the photosynthetic rate. The reduction of A. Halimus growth compared to optimum growth at 50 and 200 mM NaCl could be attributed to osmotic effect rather than the ionic one of salt stress. The inhibition of photosynthesis seemed to be resulted from limitation of CO2 due to the osmotic effect on stomatal conductance rather than the activity loss of photosynthetic machinery. The depletion of starch content along with the increase in sucrose content could imply that photosynthesis may be a limiting for A. Halimus growth. The fast coordinate induction of Na+ manipulating genes could reveal that the tolerance of A. Halimus to high concentrations evolved from its ability to regulate and control Na+ influx and efflux. V-H+-PPase may play a vital role in A. Halimus tolerance to osmotic and/or ionic stress due to its kinetics of induction. It seemed that H+-ATPase plays a pivotal role in A. Halimus tolerance to stress due to the increase in its protein level was detected with all NaCl concentrations as well as with PEG treatments. Both of these genes might be useful in improving stress tolerance in transgenic crops.
Youcef Daoud - One of the best experts on this subject based on the ideXlab platform.
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ameliorative effect of cacl2 on growth membrane permeability and nutrient uptake in Atriplex Halimus subsp schweinfurthii grown at high nacl salinity
Desalination, 2009Co-Authors: Bouzid Nedjimi, Youcef DaoudAbstract:Abstract A hydoponic culture was carried out with Atriplex Halimus subsp. schweinfurthii to investigate the effects of supplementary calcium chloride on plants grown at high NaCl concentration (400 mM). Treatments were: (1) Control: nutrient solution alone (C); (2) nutrient solution plus 400 mM sodium chloride (NaCl); (3) nutrient solution plus 20 mM calcium chloride (CaCl 2 ⁎); (4) nutrient solution plus 40 mM calcium chloride (CaCl 2 ⁎⁎); (5) nutrient solution and 400 mM NaCl plus supplementary 20 mM CaCl 2 (NaCl +CaCl 2 ⁎); and (6) 400 mM NaCl plus additional mixture of 40 mM CaCl 2 in nutrient solution (NaCl + CaCl 2 ⁎⁎). The plants grown under salt stress produced low dry weight and relative water content than those grown in standard nutrient solution and in CaCl 2 alone. Supplemental calcium chloride added to nutrient solution containing salt significantly improved growth and relative water content. Membrane permeability increased with high NaCl application and these increases in root membrane permeability were decreased with supplementary Ca. The concentration of chloride (Cl) increased highly for all treatments. Sodium (Na) concentration in plant tissues increased in both shoots and roots at high NaCl treatment. Application of supplementary Ca lowered Na concentration. Concentrations of Ca, K and N were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary Ca. The ameliorating effect of Ca on growth and physiological variables could reduce the negative effect of salinity on A. Halimus plants.
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Cadmium accumulation in Atriplex Halimus subsp. schweinfurthii and its influence on growth, proline, root hydraulic conductivity and nutrient uptake.
Flora - Morphology Distribution Functional Ecology of Plants, 2009Co-Authors: Bouzid Nedjimi, Youcef DaoudAbstract:Abstract Atriplex Halimus subsp. schweinfurthii is a newly found cadmium (Cd)-hyperaccumulator, but there have been no detailed studies on its physiological responses when Cd is hyperaccumulated. A. Halimus was grown in hydroponic conditions to investigate the effect of cadmium chloride (CdCl 2 ) on growth, water status, leaf chlorophyll concentration, proline and Cd accumulation. Treatments were prepared by adding 0, 50, 100, 200 and 400 μM CdCl 2 to the nutrient medium. Plant growth was significantly affected at high-Cd treatments. Increased CdCl 2 decreased chlorophyll concentration, transpiration and root hydraulic conductivity ( L 0 ). Hence water flux had only a little effect on the uptake of Cd in A. Halimus seedlings. In contrast, proline content increased with increasing CdCl 2 concentration. Plants accumulated substantial amount of Cd in different plant parts (shoot and root). Most of the Cd taken up was retained in roots (606.51 μg g −1 DW after 15 d at 400 μM CdCl 2 ). The addition of Cd in the culture medium affected calcium (Ca) and potassium (K) nutrition in both shoot and root. A. Halimus provides a new plant resource for exploring the mechanism of Cd hyperaccumulation and has potential for use in the phytostabilization of Cd-contaminated salt soils.