Phytochemical Analysis, Acetylcholinesterase Inhibition, Antidiabetic and Antioxidant Activities of Atriplex halimus L. (Amaranthaceae Juss.).

Mediterranean saltbush Atriplex halimus L. (Amaranthaceae) from different bioclimatic arid zones (ten wild populations) were studied. Phenols contents, flavonoids, flavonols, tannins and anthocyanins were determined and then tested for their antioxidants, antidiabetic and anti-acetylcholinesterase (AChE) activities. Levels of total polyphenols including flavonoids and flavonols, tannins and anthocyanins were high and varied significantly among analyzed populations. Nine phenolic acids and four flavonoids were identified for the first time in the methanolic fraction and quantified by liquid high-performance chromatography system HPLC (DAD). All extracts showed a substantial antioxidant activity, as assessed by DPPH assay (1,1-diphenyl-2-picrylhydrazyl free radical) (IC50DPPH=147.3for population of Seliena), Ferric Reducing Antioxidant Power (FRAP; IC50FRAP=3.2 for populations of Sousse and Kairouan), and Chelation Fer test (IC50FerCh=1.5 µg/mL for populations of El-hamma and Mednine). Atriplex halimus possessed a high inhibitory effect against α-amylase activity (up to 2.6 mg ACE/gE), a moderate activity for α-glucosidase (up to 91.0 mg ACE/gE) and AChE (up to 147.2 µg/mL) compared to standard. The analyzed populations were isolated and subdivided into three distinct groups, without any bioclimatic structuration. Enzymatic activities seem to be associated with the presence, in plant extracts, of other classes of compounds then phenols such as terpenes, sterols, saponins, coumarins and carotenoids.

High-speed countercurrent chromatography for isolation and enrichment of betacyanins from fresh and dried leaves of Atriplex hortensis L. var. "Rubra".

Betacyanins and their decarboxylated derivatives from fresh and dried edible leaves of Atriplex hortensis L. var. "Rubra" were fractionated for the first time by high-speed countercurrent chromatography. Pigments present in fresh leaf extract were separated in systems: ethanol - acetonitrile - n-propanol - ammonium sulphate - water (0.5:0.5:0.5:1.2:1.0, v/v/v/v/v) (tail-to-head mode) and tert-butyl methyl ether - n-butanol - acetonitrile - water with 0.7% heptafluorobutyric acid (2:2:1:5, v/v/v/v) (head-to-tail mode). The mobile phase flow rate was 2 mL/min and the retention of the stationary phase was 79.8 and 75.2%, respectively. Pigments from dried leaves were separated in a similar ion-pair system with heptafluorobutyric acid in different volume proportions 1:3:1:5 (head-to-tail mode) and the flow rate of the mobile phase 3 mL/min. The stationary phase retention was 64.0%. The application of the countercurrent chromatography for the fractionation of betacyanins from leaves of Atriplex hortensis enabled to isolate and pre-concentrate the pigments for further low- and high-resolution liquid chromatographic-tandem mass spectrometric detection. This study revealed the presence of 10 betacyanins in fresh and 16 in dried leaves of Atriplex hortensis. Two compounds were not previously identified in the whole Amaranthaceae family. Additionally, instead of (iso)amaranthin, celosianin and its epimer were dominant betacyanins in the Atriplex hortensis.

Protoscolicidal activity of Atriplex halimus leaves extract against Echinococcus granulosus protoscoleces.

Cystic echinococcosis, an endemic zoonosis in Algeria, is caused by the development of the helminth Echinococcus granulosus. Surgery remains the main treatment despite inducing relapse and several adverse reactions. In this context, natural scolicidal agents seem to be promising tools to overcome these reactions. In our study, we evaluated the phytochemical contents, antioxidant activity and scolicidal effect of Atriplex halimus. In this context, the aqueous extract from AH leaves (AHE) was subjected to preliminary phytochemical screening by HPLC. The in vitro antioxidant activity was determined by DPPH test. The cytotoxicity of AHE was evaluated in murine peritoneal macrophages and cell viability was examined by MTT assay. Moreover, different concentrations of AHE (20, 40, 50, 60 and 100 mg/ml) were tested on E. granulosus protoscoleces (PSC) cultures, during different times of incubation (15, 30, 60, 90, 120 and 180 min). The viability was evaluated by eosin exclusion test. The morphological and ultrastructural damages were evaluated by SEM. Our results indicate that total phenolic and flavonoids contents were 37.93 µg of Gallic acid equivalent per mg of extract (GAE/mg E) and 18.86 µg of Quercetin equivalent per mg (QE/mg E) respectively. Furthermore, AHE has an antioxidant activity with an IC50 of 0.95 mg/ml. Interestingly, the extracts did not exhibit any cytotoxic effect against murine peritoneal macrophages. Moreover, our study indicated a significant scolicidal activity time- and dose-dependent. At 60 and 100 mg/ml; and after 120 min of incubation; the mortality rate was 99.36 and 100%, respectively. The parasite's tegument is one of the plant's targets as demonstrated by SEM. Our findings show the benefits of Atriplex halimus extract as a new promising scolicidal tool in hydatid cyst treatment.

3,5-dicaffeoyl­epi-quinic acid from Atriplex gmelinii enhances the osteoblast differentiation of bone marrow-derived human mesenchymal stromal cells via WnT/BMP signaling and suppresses adipocyte differentiation via AMPK activation.

BACKGROUND: Impaired bone formation is one of the reasons behind osteoporosis. Alterations in the patterns of mesenchymal stromal cell differentiation towards adipocytes instead of osteoblasts contribute to osteoporosis progression. Natural anti-osteoporotic agents are effective and safe alternatives for osteoporosis treatment. PURPOSE: In this context, 3,5-dicaffeoyl­epi-quinic acid (DCEQA) which is a derivative of chlorogenic acid with reported bioactivities was studied for its osteogenic differentiation enhancing potential in vitro. METHODS: Anti-osteoporotic effects of DCEQA were investigated in human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) which were induced to differentiate into osteoblasts or adipocytes with or without DCEQA treatment. Changes in the osteogenic and adipogenic markers such as ALP activity and lipid accumulation, respectively, were observed along with differentiation-specific activation of mitogen activated protein kinase (MAPK) pathways. RESULTS: At 10 µM concentration, DCEQA increased the proliferation of bone marrow-derived human mesenchymal stromal cells (hBM-MSCs) during osteoblast differentiation. The expression of osteogenic markers ALP, osteocalcin, Runx2, BMP2 and Wnt 10a was upregulated by DCEQA treatment. The ALP activity and extracellular mineralization were also increased. DCEQA elevated the phosphorylation levels of p38 and JNK MAPKs as well as the activation of ß-catenin and Smad1/5. DCEQA suppressed the lipid accumulation and downregulated expression of adipogenic markers PPARγ, C/EBPα and SREBP1c in adipo-induced hBM-MSCs. DCEQA also decreased the phosphorylation of p38 and ERK MAPKs and stimulated the activation of AMPK in hBM-MSC adipocytes. CONCLUSION: DCEQA was suggested to enhance osteoblast differentiation via stimulating Wnt/BMP signaling. The adipocyte differentiation inhibitory effect of DCEQA was suggested to arise from its ability to increase AMPK phosphorylation. Overall, DCEQA was shown to possess osteogenesis enhancing and adipogenesis inhibitory properties which might facilitate its use against osteoporotic conditions.

3,5-Dicaffeoyl-epi-quinic acid inhibits the PMA-stimulated activation and expression of MMP-9 but not MMP-2 via downregulation of MAPK pathway.

Matrix metalloproteinases (MMPs), especially MMP-2 and MMP-9, are very important gelatinases that are overexpressed during tumor metastasis. Up to date, several MMP inhibitors have been developed from natural sources as well as organic synthesis. In the present study, the MMP-2 and MMP-9 inhibitory effects of 3,5-dicaffeoyl-epi-quinic acid (DCEQA), a caffeoylquinic acid derivative isolated from Atriplex gmelinii, were investigated in phorbol 12-myristate 13-acetate (PMA)-treated human HT1080 fibrosarcoma cells. Gelatin zymography and immunoblotting showed that DCEQA significantly inhibited the PMA-induced activation and expression of MMP-9 but was not able to show any effect against MMP-2. DCEQA treatment was also shown to upregulate the protein expression of tissue inhibitor of MMP-1 along with decreased MMP-9 protein levels. Moreover, the effect of DCEQA on phosphorylation of mitogen activated protein kinases (MAPKs), analyzed by immunoblotting, indicated the DCEQA inhibited the MMP-9 by downregulation of MAPK pathway. Collectively, current results suggested that DCEQA is a potent MMP-9 inhibitor and can be utilized as lead compound for treatment of pathological complications involving enhanced MMP activity such as cancer metastasis.

Atriplex halimus aqueous extract abrogates carbon tetrachloride-induced hepatotoxicity by modulating biochemical and histological changes in rats.

The objective of this study was to evaluate the potential protective effect of Atriplex halimus aqueous leaves extract (AHAE) against acute carbon tetrachloride (CCl4)-induced oxidative stress in rats. Rats were randomly divided into four groups: group (C) served as a control treated with 1 ml/(kg bw) of olive oil, and group (CCl4) was treated with 1 ml CCl4/(kg bw) dissolved in olive oil administered by intraperitoneal way. Rats of group (CCl4+AHAE) have received CCl4 and treated with 200 mg AHAE/(kg bw). Animals of group (AHAE) were treated with 200 mg/(kg bw) of AHAE. A significant increase in malondialdehyde levels in liver associated with a decrease in antioxidant enzyme activities and reduced glutathione content was observed in CCl4 group compared to controls. The administration of AHAE to CCl4+AHAE group improved all parameters studied. We conclude that CCl4 induces oxidative stress and modifies biochemical parameters and histological aspects of liver. Administration of AHAE alleviates the toxicity induced by this organic compound.

Quantitative Determination of Betaine, Choline, Acetylcholine, and 20-Hydroxyecdysone Simultaneously from Atriplex Species by UHPLC-UV-MS.

A simple, rapid, and sensitive UHPLC-UV-MS method was developed for the quantitative determination of betaine (1), choline (2), acetylcholine (3), and 20-hydroxyecdysone (4) from various species of Atriplex. The baseline separation of the four analytes was achieved on a reversed phase C 18 column within nine minutes. The mobile phase was composed of 50 mM ammonium formate in 2% methanol-water containing 5 mM sodium dodecyl sulfate (pH = 8.2) and methanol with 0.01% ammonium hydroxide. The analytical method was validated for recovery, precision, limits of detection (LOD), and limits of quantification (LOQ). The developed method was applied for the characterization and quantitation of analytes from plant parts of different Atriplex species, including A. canescens, A. fruticulosa, A. fasciculata, A. semibaccata, and A. lentiformis. Compounds 1-4 were found in a range of 0.53-1.61%, detection under limit of quantification (DUL)-0.74, DUL-0.0038, and 0-0.10% (w/w, mg in 100 mg plant material), respectively, in test samples. In leaf and fruit of A. canescens, a high content of 1, 2, and 4 were identified. The content of 1, 2, and 4 in A. canescens explains the potential implications of this native US plant for human health and nutrition. The result of this study provides a new method to analyze these phytoconstituents simultaneously in a mixture.

MOLLUSCICIDAL AND LARVICIDAL ACTIVITIES OF Atriplex inflata AERIAL PARTS AGAINST THE MOLLUSK Galba truncatula, INTERMEDIATE HOST OF Fasciola hepatica / Atividade moluscicida e larvicida das partes aéreas de Atriplex inflata contra o molusco Galba truncatula, hospedeiro intermediário da Fasciola hepatica

Fasciolosis is a widespread parasitosis of farm live-stock in many developing countries. For this reason, it is necessary to search for new substances against parasitic diseases caused by flukes. Indeed, a wide variety of terrestrial plants have been subjected to chemical and pharmacological screening in order to discover their potential for human medicinal use. The molluscicidal and larvicidal activities of Atriplex inflata were tested on Galba truncatula and Fasciola hepatica larval stages infecting this snail in Tunisia. Phytochemical tests were conducted on extracts in order to establish a meaningful relationship with molluscicidal and larvicidal activities. The molluscicidal activity was evaluated by subjecting snails to sample aqueous solutions. Accordingly, hexane, ethyl acetate, methanol and methanol-water (8:2, v-v) were used as extraction solvents. As a result, hexane and ethyl acetate extracts showed potent activity, according to the World Health Organization, giving LC50 = 7.59 mg/L and 6.69 mg/L for hexane extracts of leaves and fruits, respectively. Ethyl acetate extracts gave LC50 = 5.90 mg/L and 7.32 mg/L for leaves and fruits, successively. Molluscicidal activities of powders were less potent on snails, but active according to the World Health Organization. Hexane and ethyl acetate extracts from leaves and fruits gave potent larvicidal activities with a delay rate exceeding 45.50% (45.50- 98.92%). Phytochemical tests showed that these activities may be attributed to the presence of triterpenoids and/or sterols.

Fasciolose é uma parasitose generalizada que ocorre em animais de fazendas em muitos países em desenvolvimento. Por esta razão, é necessária a busca de novas substâncias contra as doenças parasitárias causadas por vermes. De fato, uma grande variedade de plantas terrestres foi objeto de testes farmacológicos e químicos a fim de descobrir o seu potencial para utilização em terapêutica humana. As atividades moluscicida e larvicida de Atriplex inflata foram testadas contra estágios larvários de Galba truncatula e Fasciola hepatica infectando este caracol na Tunísia. Testes fitoquímicos foram realizados com extratos a fim de estabelecer uma relação significativa com as atividades moluscicida e larvicida. A atividade moluscicida foi avaliada submetendo os caracóis a soluções aquosas. Conforme o caso, hexano, acetato de etilo, metanol e metanol-água (8:2, v-v) foram utilizados como solventes de extração. Como resultado, hexano e extratos de acetato apresentaram atividades potentes de acordo com a Organização Mundial de Saúde, resultando em LC50 = 7,59 mg/L e 6,69 mg/L para extratos de hexano de folhas e frutos, respectivamente. Extratos de acetato de etilo resultaram em LC50 = 5,90 mg/L e 7,32 mg/L para as folhas e frutos sucessivamente. Atividades moluscicidas das substâncias sob a forma de pó foram menos potentes em caracóis, mas ativas de acordo com a Organização Mundial de Saúde. Hexano e extratos de acetato de folhas e frutos apresentaram atividade larvicida potente, com uma taxa de atraso superior a 45,50% (45,50-98,92%). Testes fitoquímicos mostraram que estas atividades podem ser atribuídas à presença de triterpenóides e/ou esteróis.

Phenolic Compounds from Atriplex littoralis and Their Radiation-Mitigating Activity.

From the aerial parts of Atriplex littoralis, three new flavonoid glycosides named atriplexins I-III (1-3), a known flavonoid glycoside, spinacetin 3-O-ß-d-glucopyranoside (4), arbutin (5), and 4-hydroxybenzyl-ß-d-glucopyranoside (6) were isolated. Their structures were elucidated on the basis of detailed spectroscopic analysis, including 1D and 2D NMR (COSY, NOESY, TOCSY, HSQC, HMBC) and HRESITOF MS data. The compounds were tested for in vitro protective effects on chromosome aberrations in peripheral human lymphocytes using a cytochalasin-B-blocked micronucleus (MN) assay in a concentration range of 0.8-7.4 µM of final culture solution. Chromosomal damage was induced by 2 Gy of γ-radiation on binucleated human lymphocytes, and the effects of the compounds were tested 2 to 19 h after irradiation. The frequency of micronuclei (MNi) was scored in binucleated cells, and the nuclear proliferation index was calculated. The highest prevention of in vitro biochemical and cytogenetic damage of human lymphocytes induced by γ-radiation was exhibited by 3 (reduction of MN frequency by 31%), followed by 4 and 6.

Anticholinesterse and antioxidant investigations of crude extracts, subsequent fractions, saponins and flavonoids of atriplex laciniata L: potential effectiveness in Alzheimer's and other neurological disorders

BACKGROUND: Atriplex laciniata L. was investigated for phenolic, flavonoid contents, antioxidant, anticholinesterase activities, in an attempt to explore its effectiveness in Alzheimer's and other neurological disorders. Plant crude methanolic extract (Al.MeF), subsequent fractions; n-hexane (Al.HxF), chloroform (Al.CfF), ethyl acetate (Al.EaF), aqueous (Al.WtF), Saponins (Al.SPF) and Flavonoids (Al.FLVF) were investigated for DPPH, ABTS and H2O2 free radical scavenging activities. Further these extracts were subjected to acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities using Ellman's assay. Phenolic and Flavonoid contents were determined and expressed in mg Gallic acid GAE/g and Rutin RTE/g of samples respectively. RESULTS: In DPPH free radicals scavenging assay, Al.FLVF, Al.SPF and Al.MeF showed highest activity causing 89.41 ± 0.55, 83.37 ± 0.34 and 83.37 ± 0.34% inhibition of free radicals respectively at 1 mg/mL concentration. IC50 for these fractions were 33, 83 and 82 µg/mL respectively. Similarly, plant extracts showed high ABTS scavenging potential, i.e. Al.FLVF (90.34 ± 0.55), Al.CfF (83.42 ± 0.57), Al.MeF (81.49 ± 0.60) with IC50 of 30, 190 and 70 µg/ml respectively. further, H2O2 percent scavenging was highly appraised in Al.FLVF (91.29 ±0.53, IC50 75), Al.SPF (85.35 ±0.61, IC50 70) and Al.EaF (83.48 ± 0.67, IC50 270 µg/mL). All fractions exhibited concentration dependent AChE inhibitory activity as; Al.FLVF, 88.31 ± 0.57 (IC50 70 µg/mL), Al.SPF, 84.36 ± 0.64 (IC50 90 µg/mL), Al.MeF, 78.65 ± 0.70 (IC50 280 µg/mL), Al.EaF, 77.45 ± 0.46 (IC50 270 µg/mL) and Al.WtF 72.44 ± 0.58 (IC50 263 µg/mL) at 1 mg/mL. Likewise the percent BChE inhibitory activity was most obvious in Al.FLVF 85.46 ± 0.62 (IC50 100 µg/mL), Al.CfF 83.49 ± 0.46 (IC50 160 µg/mL), Al.MeF 82.68 ± 0.60 (IC50 220 µg/mL) and Al.SPF 80.37 ± 0.54 (IC50 120 µg/mL). CONCLUSIONS: These results stipulate that A. laciniata is enriched with phenolic and flavonoid contents that possess significant antioxidant and anticholinestrase effects. This provide pharmacological basis for the presence of compounds that may be effective in Alzheimer's and other neurological disorders.

Phytoextraction of cadmium by four Mediterranean shrub species.

The possibility of remediating contaminated soils though the use of high biomass-generating, native plant species capable of removing heavy metals is receiving increased attention. The cadmium (Cd) accumulation capacities of the native Mediterranean, perennial shrubs Atriplex halimus, Phyllirea angustifolia, Rhamnus alaternus and Rosmarinus officinalis were tested by growing transplanted specimens in a pine bark compost substrate (pH 5.6) contaminated with 100 mg Cd kg(-1). After 70 days, only R. alaternus showed reduced growth. The increase in biomass seen in all the test species enhanced the phytoextraction of Cd. However, the species behaved as metal excluders, except for the halophyte A. halimus, which behaved as an indicator plant. In this species the leaf Cd concentration reached 35 mg Cd kg(-1), with the shoot responsible for some 86% of total Cd accumulation. Atriplex halimus showed the highest bioconcentration factor (BCF) (0.36) and leaf Cd transport index (1.68); consequently, this species showed the highest Cd phytoextraction capacity.

Glaucasides A-C, three saikosaponins from Atriplex glauca L. var. ifiniensis (Caball) Maire.

From the roots of Atriplex glauca L. var. ifiniensis (Caball) Maire (syn. of Atriplex parvifolia Lowe var. genuina Maire), three new saikosaponins designated as glaucasides A-C (1-3) were isolated together with the known 3-O-ß-D-glucopyranosyl-(1 → 2)-ß-D-galactopyranosyl-saikogenin F (4). The structures of the new compounds were elucidated by extensive analysis of one-dimensional and two-dimensional NMR spectroscopy, FABMS, HR-ESIMS and chemical evidence as 13ß,28-epoxy-16ß,21ß-dihydroxyolean-11-en-3ß-yl O-ß-D-[2-O-sulfate]-glucopyranosyl-(1 → 2)-α-L-arabinopyranoside (1), 13ß,28-epoxy-16ß,21ß-dihydroxyolean-11-en-3ß-yl O-ß-D-[2-O-sulfate]-glucopyranosyl-(1 → 2)-α-L-arabinopyranosyl 21-O-{4-(secbutylamido)-butanoyl ester} (2) and 3-O-ß-D-glucopyranosyl-(1 → 2)-ß-D-galactopyranosyl saikogenin G (3). The cytotoxic activities of these compounds were evaluated against the HT-29 and HCT 116 human colon cancer cell lines.

Phytochemical and biological investigations of Atriplex semibacata R .BR. growing in Egypt.

The lipid content of Atriplex semibacata growing in Egypt was studied. The unsaponifiable fraction was identified by GLC. A series of hydrocarbons ranging from C(14)- C(28) in addition to cholesterol, stigmasterol and the triterpenoids α and ß - amyrin were identified. GLC analysis of fatty alcohols fraction revealed the presence of six fatty alcohols in which dotriacontanol (C(32)H(66)O) was the major (14.68%). Six compounds (five coumarins and one phenolic acid) were isolated for the first time from A. semibacata. The coumarin constituents isolated from the chloroform and the ethyl acetate fractions of the aqueous alcoholic extract of A. semibacata were identified as scopoletin, umbelliferorne, coumarin, scopolin, 7-methoxy coumarin in addition to a phenolic acid P-coumaric acid. Also, the flavonoidal compounds isolated from the n-butanol fraction of the plant revealed the presence of kaempferol 3-O glucoside and acacetin. Their identity was proved by m.p., TLC, PC, UV and MS analysis. The alcohol extract showed significant antimicrobial activity against G-ve bacteria, moderate activity against G+ve bacteria. On the other hand, the pet. Ether extract showed marked activity against G+ve bacteria and fungi, also the G-ve bacteria was greatly inhibited by the chloroform extract. The different extracts of the plant exhibited no cytotoxic activity against Erlich-ascites carcinoma cells line at the tested concentrations, also showed a strong antioxidant activity using DPPH.

Antioxidant activity and chemical composition of essential oil from Atriplex undulata.

The essential oil from aerial parts (stems and leaves) of Atriplex undulata (Moq) D. Dietr. (Chenopodiaceae) has been studied for its in vitro antioxidant activity. The chemical composition of the oil obtained by hydrodistillation was determined by GC and GC-MS. The major constituents were p-acetanisole (28.1%), beta-damascenone (9.3%), beta-ionone (5.1%), viridiflorene (4.7%) and 3-oxo-alpha-ionol (2.2%). The antioxidant activity of the oil was determined by two methods: Crocin bleaching inhibition (Krel = 0.72 +/- 0.15) and scavenging of the DPPH radical (IC50 = 36.2 +/- 1.6 microg/mL). The presence of active compounds like p-acetanisole, carvone, vanillin, 4-vinylguaiacol, guaiacol, terpinen-4-ol and alpha-terpineol could explain the antioxidant activity observed for this oil.

Cadmium has contrasting effects on polyethylene glycol-sensitive and resistant cell lines in the Mediterranean halophyte species Atriplex halimus L.

Beside a direct toxicity, cadmium impact on plants involves both a secondary-induced water stress and an oxidative stress. Proliferating cell lines of Atriplex halimus were selected for their sensitivity or resistance to polyethylene glycol (PEG 10,000, 20%) and then exposed to 100 microM CdCl2 in the simultaneous presence or absence of PEG 20% or 150 mM NaCl. The PEG resistant cell line exhibited a higher growth in the presence of Cd than the sensitive line, although Cd acccumulation was higher in the former than in the latter. Exogenous PEG induced an increase in Cd concentration in the sensitive but not in the resistant cell line while NaCl induced a decrease in Cd accumulation in both cell lines. In the presence of Cd alone, the water content (WC) was higher and the osmotic potential was lower in PEG-sensitive than in PEG resistant line. The presence of PEG in the Cd-containing medium increased the WC and decreased the osmotic potential in PEG-resistant line comparatively to Cd stress alone, while an inverse trend was observed for the sensitive line. The PEG-resistant cell line displayed a higher ability to cope with oxidative stress in relation to an increase of endogenous antioxidants (glutathione and ascorbic acid), a high constitutive superoxide dismutase (EC 1.15.1.1) activity and an efficient Cd-induced increase in glutathione reductase (GR) (EC 1.6.4.1) and ascorbate peroxidase (APX) (EC 1.11.1.11). Cadmium tolerance in PEG-resistant line is thus not related to any strategy of Cd exclusion or osmotic adjustment but to tolerance mechanisms allowing the tissue to restrict the deleterious impact of accumulated Cd.

Abscisic acid has contrasting effects on salt excretion and polyamine concentrations of an inland and a coastal population of the Mediterranean xero-halophyte species Atriplex halimus.

BACKGROUND AND AIMS: Different populations of the Mediterranean xerohalophyte species Atriplex halimus exhibit different levels of resistance to salt and osmotic stress depending on the nature of the osmocompatible solute they accumulate. There is, however, no conclusive description of the involvement of abscisic acid (ABA) in the plant response to NaCl or osmotic stress in this species. METHODS: Seedlings issued from an inland water-stress-resistant population (Sbikha) and from a coastal salt-resistant one (Monastir) were exposed in nutrient solutions to NaCl (40 or 160 mm) or to 15 % PEG for 1 d and 10 d in the presence or absence of 50 microm ABA. KEY RESULTS: Plants from Sbikha accumulated higher amounts of ABA in response to osmotic stress than those of Monastir, while an opposite trend was recorded for NaCl exposure. Exogenous ABA improved osmotic stress resistance in Monastir through an improvement in the efficiency of stomatal conductance regulation. It also improved NaCl resistance in Sbikha through an increase in sodium excretion through the external bladders. It is suggested that polyamines (spermidine and spermine) are involved in the salt excretion process and that ABA contributes to polyamine synthesis as well as to the conversion from the bound and conjugated to the free soluble forms of polyamine. Proline accumulated in response to osmotic stress and slightly increased in response to ABA treatment while glycinebetaine accumulated in response to salinity and was not influenced by ABA. CONCLUSIONS: It is concluded that ABA is involved in both salt and osmotic stress resistance in the xerohalophyte species Atriplex halimus but that it acts on different physiological cues in response to those distinct environmental constraints.