Zeineb Ouerghi - Academia.edu (original) (raw)

Papers by Zeineb Ouerghi

Heavy metals such Zn, Pb, Cu and Cd can cause a non-degradable pollution in numerous sites in Fra... more Heavy metals such Zn, Pb, Cu and Cd can cause a non-degradable pollution in numerous sites in France as well as in Tunisia, or elsewhere. This pollution resulting from various human polluting activities, related to industry or mining, is often diffuse in soils. Vegetation can play an important role in decontaminating these soils, their rehabilitation, and making their environment safer. For a better understanding of metal reactivity, a review of general knowledge concerning this kind of polluting metals and plant tolerance mechanisms is presented. A study was also conducted on the accumulation of the following metals: Cd, Cu, Zn, Pb and Ni, in their localisation in plant tissues and their induced toxic effects. The most general visible, but nonspecific symptom of heavy metal stress is growth inhibition, which has been investigated in many plants, including Atriplex. A cultivation of annual Atriplex plants was conducted according to hydroponic experimental design. The experimental ap...

Drought stress is considered as a restricting factor for plant products. Plants differ in their a... more Drought stress is considered as a restricting factor for plant products. Plants differ in their ability to tolerate water stress. Atriplex hortensis is a xero-halophyte, C3 shrub. This study examined the influence of drought on antioxidant activity, growth and content of carotenoids and anthocyanins of the A. hortensis leaves using two varieties: green orach (var. purpurea) and red orach (var. rubra). To study the enzymatic response of the Atriplex plants against water deficit, antioxidant enzymes in the leaves were analyzed, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). We observed that under water stress both varieties decreased the activity of SOD in leaf tissue, especially in plants grown in severe water deficit. In the exposure to moderate and mild drought stress, more reactive oxygen species might promote the increase in activities of antioxidant enzymes such as CAT and APX, as found in leaves of the Atriplex pla...

International Journal of Environmental Research

The toxicity of four potentially toxic trace elements (Cu, Ni, Pb and Zn) to Annual Atriplex (A. ... more The toxicity of four potentially toxic trace elements (Cu, Ni, Pb and Zn) to Annual Atriplex (A. hortensis and A. rosea) was examined to determine if this plant showed sufficient tolerance to be used to phytoremediate soils polluted with these heavy metals. The plant growth expressed as shoot and root dry weight of Atriplex plant was adversely inhibited when exposed to high concentrations of polluted soil. Significant increases in chlorophyll content were observed in leaves for three Atriplex varieties after the plants were exposed to stress treatments. The carotenoid and anthocyanin content also decreased. Red variety of Atriplex accumulated more anthocyanins in leaves than green and rosea ones. The lipid peroxidation increased, considerably at 100% polluted soil, which is a typical plant reaction to the oxidative stress. We proposed for the reduction state of photosynthetic parameters to be a useful tool in bioassay toxicity testing of metal polluted soil. These results demonstrat...

Cited By (since 1996):2, Export Date: 18 October 2014

Investigations on the effects of water-deficit stress conditions on the physiological characteris... more Investigations on the effects of water-deficit stress conditions on the physiological characteristics of plants may provide a means to understand the basis of drought resistance. Atriplex spp. have been used as a resource for the rehabilitation of degraded land. The responses of two varieties of Atriplex hortensis [green orach (A. hortensis L. var. purpurea) and red orach (A. hortensis L. var. rubra)] to four levels of soil moisture (100, 80, 60, or 40% of field capacity) were investigated. The experiment was conducted under greenhouse conditions. Growth declined progressively with the application of increasing water stress. Water-stressed plants exhibited significant reductions in height and biomass. Water-deficit stress also caused a significant decline in total leaf area, but had no significant effect on leaf water content in red orach. Reductions in soil water content caused reductions in the relative water content (RWC) of leaves in both varieties of A. hortensis, but the decre...

Notulae Botanicae Horti Agrobotanici Cluj-Napoca

This study examined the influence of salt levels on antioxidant activity and content of carotenoi... more This study examined the influence of salt levels on antioxidant activity and content of carotenoids and anthocyanins of the A. hortensis leaves using two varieties: green orach (var. purpurea) and red orach (var. rubra). Seeds of Atriplex were exposed to 0, 90, 180 and 260 mM NaCl for 3 months and seeds were sown in an earthen pot. Overall levels of ascorbate peroxidase (APX) and glutathione reductase (GR) activity were significantly elevated. Salt stress caused a significant decline in tissue concentrations of catalase (CAT) and superoxide dismutase (SOD). However, 90 mM NaCl did not modify these parameters, which remains similar to control values. Activities of APX and CAT were increase whether the shoots of A. hortensis var. purpurea were grown in the presence of 180 mM NaCl. Thus although some indications of oxidative stress accompany exposure of this salt-tolerant Atriplex varieties to salinity, mechanisms appear to exist within its shoot tissue to permit the tolerance of such ...

Plant and Soil, 2010

Arabidopsis thaliana seedlings were grown in hydroponic culture under controlled conditions in me... more Arabidopsis thaliana seedlings were grown in hydroponic culture under controlled conditions in mediums with different NO 3 − /NH 4 + ratios. The mediums were not buffered, against pH change, but their pH was reset at pH 5.5 each 2 days. When ammoniacal N source was predominant, the whole plant biomass deposition was diminished, parallely to several parameters which revealed degraded leaf physiological status, such as leaf chlorosis associated with diminished chlorophyll content, lowered K + , Ca 2+ , and water content, along with restricted leaf expansion, and apparition of cellular stress symptoms. However, leaf functioning for biomass production did not seem affected, since biomass production rate per unit leaf surface area remained unchanged. Indeed, the main factor of decrease biomass production was leaf elimination and/or repression of leaf initiation. The results are discussed in the context of literature data on the effects of NH 4 + on ion fluxes at the root level and properties of K + transport systems in Arabidopsis. Disturbance of mineral (cationic) nutrition by NH 4 + seemed to be a major cause of the detrimental effect of ammoniacal nutrition.

Biosaline Agriculture and Salinity Tolerance in Plants, 2006

Salinity is an extending environmental issue which compromises the long-term sustainability of ag... more Salinity is an extending environmental issue which compromises the long-term sustainability of agriculture, especially in the coastal semi-arid areas [1]. This is the case in Tunisia, where the semi-arid Mediterranean climate prevails (mean annual precipitation of 200–700 mm). Subsequently, around 10% of the whole territory would be salt-affected [2]. Halophytes have evolved a wide range of attributes (morphological, physiological and

Biosaline Agriculture and Salinity Tolerance in Plants, 2006

Plant Physiology and Biochemistry, 2007

Morpho-physiological responses to bicarbonate-induced Fe deficiency were investigated in five Vit... more Morpho-physiological responses to bicarbonate-induced Fe deficiency were investigated in five Vitis vinifera L. Tunisian varieties (Khamri, Blanc3, Arich Dressé, Beldi, and Balta4). One-month-old woody cuttings were cultivated for 85days on a free calcareous soil irrigated with tap water containing increasing bicarbonate levels (0, 4, 8, 12, and 16mM NaHCO(3)). After this screening, a second experiment compared root biochemical responses of two contrasting genotypes (tolerant-sensitive) dealing with bicarbonate-induced iron deprivation (20microM Fe+/-10mM HCO(3)(-)) for 75days. Using morpho-physiological criteria, grapevine tolerance to HCO(3)(-)-induced Fe shortage appeared to be genotype-dependent: Balta4 and Beldi varieties showed the highest leaf-chlorosis score (especially at the extreme HCO(3)(-) levels), in contrast to Khamri variety. Growth parameters (shoot height, total leaf area, leaf number, and biomass production) as well as juvenile leaf chlorophyll content were also differently affected depending on both genotype and bicarbonate dose. At 16mM HCO(3)(-), Khamri was the less sensitive variety, contrasting with Balta4. On the other hand, chlorophyll content correlated positively with HCl-extractible Fe content of the juvenile leaves, suggesting that the grapevine response to iron deficiency may partly depend on to the plant ability to adequately supply young leaves with this element. Root biochemical responses revealed a relatively higher root acidification capacity in Khamri (tolerant) under Fe-deficiency while no significant changes occurred in Balta4 (sensitive). In addition, Fe(III)-reductase and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activities were strongly stimulated by Fe-deficiency in Khamri, while remaining constant in Balta4. These findings suggest that biochemical parameters may constitute reliable criteria for the selection of tolerant grapevine genotypes to iron chlorosis.

Plant Physiology and Biochemistry, 2010

Soils and ground water in nature are dominated by chloride and sulphate salts. There have been se... more Soils and ground water in nature are dominated by chloride and sulphate salts. There have been several studies concerning NaCl salinity, however, little is known about the Na 2 SO 4 one. The effects on antioxidative activities of chloride or sodium sulphate in terms of the same Na þ equivalents (25 mM Na 2 SO 4 and 50 mM NaCl) were studied on 30 day-old plants of Ocimum basilicum L., variety Genovese subjected to 15 and 30 days of treatment. Growth, thiobarbituric acid reactive substances (TBARS), relative ion leakage ratio (RLR), hydrogen peroxide (H 2 O 2 ), ascorbate and glutathione contents as well as the activities of ascorbate peroxidase (APX, EC 1.11.1.11); glutathione reductase (GR, EC 1.6.4.2) and peroxidases (POD, EC 1.11.1.7) were determined. In leaves, growth was more depressed by 25 mM Na 2 SO 4 than 50 mM NaCl. The higher sensitivity of basil to Na 2 SO 4 was associated with an enhanced accumulation of H 2 O 2 , an inhibition of APX, GR and POD activities (with the exception of POD under the 30-day-treatment) and a lower regeneration of reduced ascorbate (AsA) and reduced glutathione (GSH). However, the changes in the antioxidant metabolism were enough to limit oxidative damage, explaining the fact that RLR and TBARS levels were unchanged under both Na 2 SO 4 and NaCl treatment. Moreover, for both salts the 30-day-treatment reduced H 2 O 2 accumulation, unchanged RLR and TBARS levels, and enhanced the levels of antioxidants and antioxidative enzymes, thus achieving an adaptation mechanism against reactive oxygen species. (I. Tarchoune), csgherri@agr.unipi. it (C. Sgherri), ricizzo@agr.unipi.it (R. Izzo), Mokhtar.Lachaal@fst.rnu.tn (M. Lachaal), Zeineb.Ouerghiabidi@fst.rnu.tn (Z. Ouerghi).

Journal of the Science of Food and Agriculture, 2012

BACKGROUND: Three annual Atriplex species -A. hortensis var. purpurea, A. hortensis var. rubra an... more BACKGROUND: Three annual Atriplex species -A. hortensis var. purpurea, A. hortensis var. rubra and A. rosea -growing on soil with various levels of the heavy metals copper, lead, nickel, and zinc, have been investigated.

Journal of Plant Physiology, 2006

Thellungiella halophila seedlings grown on a solid substrate for 25 days on standard medium were ... more Thellungiella halophila seedlings grown on a solid substrate for 25 days on standard medium were challenged with NaCl. Growth, tissue hydration, ion accumulation, photosynthesis, lipid peroxidation and antioxidant enzymatic activities were studied on rosette leaves. Three accessions of Arabidopsis thaliana were cultivated under the same conditions. During the first two weeks of salt treatment, the growth of T. halophila leaves was restricted by NaCl. No significant difference appeared between T. halophila and A. thaliana concerning biomass deposition, or hydric and ionic parameters. However, all A. thaliana plants displayed foliar damage, and died during the third week of salt (50mM NaCl) treatment. Almost all (94%) T. halophila plants remained alive, but did not display any sign of altered physiological condition. Tissue hydration, chlorophyll content, stomatal conductance, photosynthetic quantum yield, and photosynthetic rate were very similar to those of control plants. Lipid peroxidation, estimated from thermoluminescence, was very low and insensitive to salt treatment. Only slight changes occurred in antioxidant enzymatic activities (SOD, several peroxidases, and catalase). From the absence of physiological disorder symptoms, we infer that salt was efficiently compartmentalized in leaf vacuoles. In salt-treated A. thaliana, the photosynthetic quantum yield was diminished, and lipid peroxidation was augmented. These observations reinforce the conclusion that T. halophila could accumulate salt in its leaves without damage, in contrast to A. thaliana.

Journal of Plant Physiology, 2007

Thellungiella halophila and Arabidopsis thaliana were irrigated with medium containing NaCl at va... more Thellungiella halophila and Arabidopsis thaliana were irrigated with medium containing NaCl at various concentrations. The salt treatment resulted in a restriction of rosette biomass deposition in both species. In A. thaliana leaves, this inhibition was stronger than for T. halophila and was associated with strong inhibition of both leaf initiation and leaf expansion. At highest medium salinity, A. thaliana accumulated Na(+) and Cl(-) at higher levels than T. halophila, but similar leaf dehydration was observed in the two species. Proline accumulation, which increased with NaCl concentration, did not differentiate the two species. The magnitude of the electrolyte leakage and the level of lipid peroxidation (assessed through hydroxy fatty acid content) were modest in T. halophila and quite marked in A. thaliana. The detrimental effects of the salt on photosynthetic activity and stomatal conductance of A. thaliana leaves were much more important than in T. halophila leaves. The abundance of the CDSP32 thioredoxin, a critical component of the defence system against oxidative damage and lipid peroxidation, was found to be higher in T. halophila than in A. thaliana under control conditions and salt treatment. These results suggest that the rosette leaves of T. halophila exhibit more efficient protective mechanisms against Na(+) metabolic toxicity than those of A. thaliana.

Journal of Plant Physiology, 2013

The changes observed photosystem I activity of lettuce plants exposed to iron deficiency were inv... more The changes observed photosystem I activity of lettuce plants exposed to iron deficiency were investigated. Photooxidation/reduction kinetics of P700 monitored as A 820 in the presence and absence of electron transport inhibitors and acceptors demonstrated that deprivation in iron decreased the population of active photo-oxidizable P700. In the complete absence of iron, the addition of plant inhibitors (DCMU and MV) could not recover the full PSI activity owing to the abolition of a part of P700 centers. In leaves with total iron deprivation (0 M Fe), only 15% of photo-oxidizable P700 remained. In addition, iron deficiency appeared to affect the pool size of NADP + as shown by the decline in the magnitude of the first phase of the photooxidation kinetics of P700 by FR-light. Concomitantly, chlorophyll content gradually declined with the iron concentration added to culture medium. In addition, pronounced changes were found in chlorophyll fluorescence spectra. Also, the global fluorescence intensity was affected. The above changes led to an increased rate of cyclic electron transport around PSI mainly supported by stromal reductants.

Journal of Plant Nutrition and Soil Science, 2007

The interactive effects of salinity and potassium (K + ) availability on biomass production, wate... more The interactive effects of salinity and potassium (K + ) availability on biomass production, water status, and ionic composition were investigated in Hordeum maritimum, an annual grass growing natively on saline soils. Plants were grown for 7 weeks on Hewitt nutrient solution supplied with NaCl (0, 100, 150, 200, and 300 mM) combined with low (0.232 mM) or high (5.8 mM) K + levels. Independent of potassium availability, dry matter of both roots and shoots decreased consistently with increasing NaCl levels in the culture medium, in association with a significant reduction of the shoot water content. This salt-induced growth reduction did not result from a restriction of K + nutrition, since H. maritimum expressed similar growth under both low and high K + supply. NaCl decreased shoot K + concentrations. This effect was more pronounced in plants grown at high K + supply than in plants grown at low K + supply. This result suggests that the absorption systems were strongly selective for K + , and that this selectivity was enhanced by salt.

Journal of Plant Nutrition, 2012

Seeds of lettuce, var. Romaine were subjected to different priming treatments such as water, pota... more Seeds of lettuce, var. Romaine were subjected to different priming treatments such as water, potassium nitrate (KNO3) and gibberellic acid (GA3). Seedlings obtained from primed (Pr) and nonprimed (NP) seeds were grown in a hydroponic culture system supplemented with 0, 100 or 200 mM sodium chloride (NaCl). The different physiological and biochemical responses were studied 15 days after treatment. Under NaCl, the

Journal of Photochemistry and Photobiology B: Biology, 2011

Fenugreek (Trigonella foenum graecum) seedlings were exposed to increasing NaCl concentrations in... more Fenugreek (Trigonella foenum graecum) seedlings were exposed to increasing NaCl concentrations in the growth medium to examine the effect of salt stress on the electron transport reactions of photosynthesis. Activities of both photosystem II (PSII), measured by chlorophyll fluorescence, and photosystem I (PSI), measured by P700 photooxidation, were decreased by salt stress. The inhibition proceeded in a two step manner. At the lower salt concentrations used and shorter exposition periods, electron transfer between the quinone acceptors of PSII, Q A and Q B , was strongly retarded as shown by an increased amplitude of the OJ phase of the OJIP chlorophyll fluorescence induction traces and slowed chlorophyll fluorescence relaxation kinetics following a single turn-over flash. The above indicated a disturbance of the Q B binding site likely associated with the first step of photoinhibition. In the second step, strong photoinhibition was observed as manifested by increased F 0 values, declined F v /F 0 and loss of photoactive P700.

Journal of Agricultural and Food Chemistry, 2010

Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about t... more Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about the impact of genotype and salinity on biochemical and molecular processes in the leafy vegetable lettuce. We report here evaluations of two lettuce types, Verte (NaCl tolerant) and Romaine (NaCl sensitive), under iso-osmotic 100 mM NaCl and 77 mM Na(2)SO(4) treatments. As compared to Romaine, NaCl-treated Verte displayed better growth, contained lower levels of inorganic cations in leaves, and possessed superior antioxidative capacity due to enhanced carotenoid and phenolics biosynthesis and more active antioxidative enzymes resulting in reduced membrane damage. Both genotypes had relatively similar growth patterns under Na(2)SO(4) treatment, but Romaine showed enhanced root lignification, greater malondialdehyde formation, and suppressed Fe-superoxide dismutase expression in roots as compared with Verte.

Environmental and Experimental Botany, 2006

The present study focuses on the sodium regulation mechanisms and the photosynthetic activity of ... more The present study focuses on the sodium regulation mechanisms and the photosynthetic activity of the halophyte Cakile maritima, in response to 6 week-exposure to increasing salinity (0-500 mM NaCl). Relative growth rate (RGR) was transiently enhanced by the application of 100 mM NaCl and a further increase in salinity either had no effect or decreased RGR. Concomitant increase in shoot Na + accumulation and leaf succulence in salt-treated plants suggested that this halophyte may use the inclusive strategy when dealing with salinity. This assumption was supported by the increase of the leaf vacuolar V H + -ATPase activity up to 300 mM NaCl and the absence of salt excretion structures at the leaf surface. Plasma membrane PM H + -ATPase activity was stimulated at the intense salinities, whereas that of mitochondrial/chloroplast F H + -ATPase declined progressively at supra-optimal salinites. Photosynthesis parameters (CO 2 assimilation rate, stomatal conductance, sub-stomatal CO 2 concentration, transpiration rate and Rubisco specific activity) were significantly increased at the optimal salinity (100 mM NaCl), as compared to the control. Higher salt levels impaired photosynthetic capacity of C. maritima mainly via a stomatal limitation, as stomatal conductance was the most reduced factor. Irrespective of salt treatment, PEPC specific activity was lower than that of Rubisco. Both nitrogen-use efficiency (NUE) and photosynthetic nitrogen-use efficiency (PNUE) were significantly high at 100 mM NaCl. Further increase in salinity led to a substantial reduction of PNUE, which might have been mainly due to salt-induced leaf succulence.

International Journal of Environmental Research

Cited By (since 1996):2, Export Date: 18 October 2014

Notulae Botanicae Horti Agrobotanici Cluj-Napoca

Plant and Soil, 2010

Biosaline Agriculture and Salinity Tolerance in Plants, 2006

Plant Physiology and Biochemistry, 2007

Plant Physiology and Biochemistry, 2010

Journal of the Science of Food and Agriculture, 2012

Journal of Plant Physiology, 2006

Journal of Plant Physiology, 2007

Journal of Plant Physiology, 2013

Journal of Plant Nutrition and Soil Science, 2007

Journal of Plant Nutrition, 2012

Journal of Photochemistry and Photobiology B: Biology, 2011

Journal of Agricultural and Food Chemistry, 2010

Environmental and Experimental Botany, 2006