tahar ghnaya - Academia.edu (original) (raw)

Papers by tahar ghnaya

Journal of Proteome Research, 2013

Among heavy metal stressors, cadmium (Cd) pollution is one leading threat to the environment. In ... more Among heavy metal stressors, cadmium (Cd) pollution is one leading threat to the environment. In this view, research efforts have been increasingly put forward to promote the individuation of phytoextractor plants that are capable of accumulating and withstanding the toxic metals, including Cd, in the aerial parts. We hereby adopted the hyperaccumulator B. juncea (Indian mustard) as a model to investigate plant responses to Cd stress at low (25 μM) and high (100 μM) doses. Analytical strategies included mass-spectrometry-based determination of Cd and the assessment of its effect on the leaf proteome and metabolome. Results were thus integrated with routine physiological data. Taken together, physiology results highlighted the deregulation of photosynthesis efficiency, ATP synthesis, reduced transpiration, and the impairment of light-independent carbon fixation reactions. These results were supported at the proteomics level by the observed Cd-dependent alteration of photosystem components and the alteration of metabolic enzymes, including ATP synthase subunits, carbonic anhydrase, and enzymes involved in antioxidant responses (especially glutathione and phytochelatin homeostasis) and the Calvin cycle. Metabolomics results confirmed the alterations of energy-generating metabolic pathways, sulfur-compound metabolism (GSH and PCs), and Calvin cycle. Besides, metabolomics results highlighted the up-regulation of phosphoglycolate, a byproduct of the photorespiration metabolism. This was suggestive of the likely increased photorespiration rate as a means to cope with Cd-induced unbalance in stomatal conductance and deregulation of CO2 homeostasis, which would, in turn, promote CO2 depletion and O2 (and thus oxidative stress) accumulation under prolonged photosynthesis in the leaves from plants exposed to high doses of CdCl2. Overall, it emerges that Cd-stressed B. juncea might rely on photorespiration, an adaptation that would prevent the over-reduction of the photosynthetic electron transport chain and photoinhibition.

Journal of Plant Physiology, 2006

Changes in lipid content and fatty acid composition were determined in leaves of two halophytes: ... more Changes in lipid content and fatty acid composition were determined in leaves of two halophytes: Sesuvium portulacastrum and Mesembryanthemum crystallinum exposed to cadmium (Cd). Experiments were carried out using young small-sized plants grown hydroponically (S. portulacastrum) or aseptically germinated seeds (M. crystallinum). Cd treatment was applied at different concentrations (0, 50, 100 and 200 mM) for 30 days. At high cadmium doses (200 mM), contents of total lipids (TL) and lipid fractions including galactolipids (GL), phospholipids (PL) and neutral lipids (NL) decreased more in M. crystallinum leaves than in S. portulacastrum leaves. Moreover, there were no significant changes in the total fatty acid composition of S. portulacastrum leaves during metal treatment. In contrast, M. crystallinum leaves showed a decrease in the percentage of the tri-unsaturated fatty acid (C18:3), and a corresponding increase in the percentage of di-unsaturated fatty acid (C18:2). These different responses suggested that S. portulacastrum seems to be more feasible for phytoremediation.

Journal of Experimental Botany, 2009

Physiological properties involved in divergent cadmium (Cd) accumulation among rice genotypes wer... more Physiological properties involved in divergent cadmium (Cd) accumulation among rice genotypes were characterized using the indica cultivar 'Habataki' (high Cd in grains) and the japonica cultivar 'Sasanishiki' (low Cd in grains). Time-dependence and concentration-dependence of symplastic Cd absorption in roots were revealed not to be responsible for the different Cd accumulation between the two cultivars because root Cd uptake was not greater in the Cd-accumulating cultivar 'Habataki' compared with 'Sasanishiki'. On the other hand, rapid and greater root-toshoot Cd translocation was observed in 'Habataki', which could be mediated by higher abilities in xylem loading of Cd and transpiration rate as a driving force. To verify whether different abilities in xylem-mediated shoot-to-root translocation generally account for the genotypic variation in shoot Cd accumulation in rice, the world rice core collection, consisting of 69 accessions which covers the genetic diversity of almost 32 000 accessions of cultivated rice, was used. The results showed strong correlation between Cd levels in xylem sap and shoots and grains among the 69 rice accessions. Overall, the results presented in this study revealed that the root-to-shoot Cd translocation via the xylem is the major and common physiological process determining the Cd accumulation level in shoots and grains of rice plants.

In this study, we investigated the effect of Zincum Metallicum (ZM) on zinc (Zn) toxicity in the ... more In this study, we investigated the effect of Zincum Metallicum (ZM) on zinc (Zn) toxicity in the plant species Lepidium sativum. We focused on growth, Zn uptake and numerous biochemical parameters. Seedlings were hydroponically subjected during 7 days to 0.05, 500, 1000, 1500 and 2000 µM Zn2+, in the absence or presence of 15ch or 9ch ZM. In the absence of ZM, Zn induced negative effect on growth especially at the dose of 2mM. Zn induced also chlorosis, reduced total chlorophyll and/or carotenoid content and increased the level of malondialdehyde (MDA). Under Zn-toxicity (500, 1000 and 1500 µM), the superoxide dismutase (SOD), catalase (CAT), gaiacol peroxidase (GPX) and glutathione reductase (GR) activities were increased and/or unaltered, while at 2000 µM Zn affected the activity of these enzymes. At the highest Zn level (2 mM), proline and total polyphenols and flavonoids contents were markedly induced in leaves and roots of L. sativum. Additionally, the supply of ZM in the nutri...

Soil contamination by toxic metals is a major environmental problem. These pollutants, contained ... more Soil contamination by toxic metals is a major environmental problem. These pollutants, contained in anthropogenic wastes, cannot be biodegraded and accumulate in soils and transported to human through the consumption of contaminated aliments or smoking. Several recent researchers showed that these elements are able to generate many diseases as cancer and renal or kidney dysfunctions.

World Academy of Science, Engineering and Technology, International Journal of Animal and Veterinary Sciences, 2015

In this note, we study the classification of Z 4-codes. For some special cases (k 1 , k 2), by ha... more In this note, we study the classification of Z 4-codes. For some special cases (k 1 , k 2), by hand, we give a classification of Z 4-codes of length n and type 4 k 1 2 k 2 satisfying a certain condition. Our exhaustive computer search completes the classification of Z 4-codes of lengths up to 7.

Pakistan Journal of Botany, 2021

Salinity is one of the main abiotic constraints affecting crop productivity. Recently, it is repo... more Salinity is one of the main abiotic constraints affecting crop productivity. Recently, it is reported that exogenous application of spermidine (Spd) could significantly alleviate the effect of salt stress. In this study, we aim to evaluate the effects of Spd application on salt stress resistance in two durum wheat (Triticum durum) varieties (Karim and Razzek) in Tunisia. Seedlings of both varieties were subjected to different NaCl concentrations (0, 20, 50, 100, 150 and 200 mM) in the presence and absence of 1 mM of Spd for 10 days. Results showed that Spd significantly increased the weight of both fresh and dry matter of NaCl-stressed plants. Similarly, Spd increased soluble sugars, and chlorophylls a and b contents particularly under 150 and 200 mMNaCl. However, exogenous Spd application decreased the content of proline and the activity of aminating glutamate dehydrogenase (GDH) enzyme. Our analysis, suggested that the application of Spd could be used as an effective approach in alleviating the NaCl-induced toxic effect in durum wheat.

Chemosphere, 2019

The cytokinin-zeatine riboside increased resistance to trans heavy metals in the halophyte plant ... more The cytokinin-zeatine riboside increased resistance to trans heavy metals in the halophyte plant species in the absence but not in the Kosteletzkya pentacarpos presence of NaCl, (2019),

Environmental Science and Pollution Research, 2019

Halophytes are able to tolerate relatively high concentrations of hazardous metals in a growing s... more Halophytes are able to tolerate relatively high concentrations of hazardous metals in a growing substrate, what makes them suitable candidates for phytoremediation of metal-contaminated soils. In this work, we aimed to study the physiological responses of the halophyte Sesuvium portulacastrum L. to Ni, with main focus on Ni localization, compartmentation and ligand environment, to decipher Ni tolerance and toxicity mechanisms. Seedlings were grown in hydroponic nutrient solution containing 0, 25, 50 and 100 μM Ni as NiCl 2 for 3 weeks. Ni localization in leaves was assessed by micro-proton-induced X-ray emission (micro-PIXE). Ni ligand environment was studied by Ni K-edge X-ray absorption near edge structure (XANES). In addition, Ni-soluble, weakly bound/exchangeable and insoluble leaf tissue fractions were determined by sequential extraction. Results show that S. portulacastrum is able to tolerate up to~500 μg g −1 dry weight (DW) of Ni in the shoots without significant growth reduction. At higher Ni concentrations (> 50 μM Ni in nutrient solution), chloroses were observed due to the accumulation of Ni in photosynthetically active chlorenchyma as revealed by micro-PIXE. Water storage tissue represented the main pool for Ni storage. Incorporation of Ni into Ca-oxalate crystals was also observed in some specimens, conferring tolerance to high leaf Ni concentrations. The majority of Ni (> 70%) was found in soluble tissue fraction. Ni K XANES revealed Ni bound mainly to O-(55%) and N-ligands (45%). Ni toxicity at higher Ni levels was associated with Ni binding to amino groups of proteins in cytosol of chlorenchyma and increased level of lipid peroxidation. Proline levels also increased at high Ni exposures and were associated with Ni-induced oxidative stress and alteration of water regime.

Applied Soil Ecology, 2019

The present work aims to characterize native bacteria from the saline rhizosphere of Sulla carnos... more The present work aims to characterize native bacteria from the saline rhizosphere of Sulla carnosa and to identify promising rhizobacteria isolates able to ameliorate the salt tolerance of this species. Bacteria were screened in vitro for salt tolerance capacity and plant growth promoting characteristics (PGP). Selected NaCl-tolerant bacteria showing a high PGP potential were further characterized for plant promotion effects on the growth of S. carnosa under salt stress (200 mM NaCl). Three putative salt-tolerant strains that showed multiple PGP-traits identified as Acinetobacter sp. (Br3), Pseudomonas putida (Br18) and Curtobacterium sp. (Br20) were selected for inoculation study. In a greenhouse experiment, NaCl significantly disturbed physiological parameters in non-inoculated S. carnosa. In these plants, NaCl reduced growth, increased foliar proline and malondialdehyde concomitant to Na + shoot concentrations. However, bacterial inoculation with selected PGP isolates ameliorated significantly plant growth and alleviated salt-induced physiological disturbances. Hence, as compared to non-inoculated plants, inoculation provided a significant increase in dry biomass and increased photosynthetic efficiency and chlorophyll leaf content under saline condition. Additional analysis showed that microbial inoculation also enhanced total soluble sugars content and antioxidant enzymes activities thereby preventing reactive oxygen species (ROS)-induced oxidative damage in plants. These results suggest that the inoculation of NaCl-stressed plants with selected salt-tolerant PGPR inocula exert beneficial effects on plant growth by alleviating salt-induced toxicity stress on plant growth and development.

Plant physiology and biochemistry : PPB, 2016

It has been shown that halophytes are able to successfully cope with heavy metal toxicity, sugges... more It has been shown that halophytes are able to successfully cope with heavy metal toxicity, suggesting their possible use for remediation of metal contaminated soils. In this work, Ni tolerance and accumulation in two halophytes, Sesuvium portulacastrum (L.) L. and Cakile maritima Scop. was investigated. Seedlings of both species were subjected hydroponically during 21 days to 0, 25, 50, and 100 μM of NiCl2. The growth and photosynthesis parameters revealed that S. portulacastrum tolerates Ni better than C. maritima. The photosynthesis activity, chlorophyll content and photosystem II integrity were less impacted in Ni-treated S. portulacastrum as compared to C. maritima, although, Ni accumulated in higher concentrations in the shoots of S. portulacastrum (1050 μg g-1 DW) than in those of C. maritima (550 μg g-1 DW). The subcellular fractionation of Ni in the shoots of both species showed that C. maritima accumulated about 65% of Ni in the soluble fraction, while 28% was associated wi...

South African Journal of Botany, 2017

Among heavy metals, nickel, cadmium and lead have received a particular attention not only as pot... more Among heavy metals, nickel, cadmium and lead have received a particular attention not only as potent hazards to human health but also given their constant increase in the environment and bioaccumulation throughout the food-chain. In plants, these metals may either directly or indirectly cause a broad range of physiological and biochemical dysfunctions culminating ultimately in the sharp decline of crop production. Here, we present new insights regarding the mechanisms governing metal phytotoxicity. In addition, we emphasize the potential interest of halophytic plants in the framework of the phytoremediation approach which has emerged as an environmental-friendly technology contributing to the extraction of heavy metal from contaminated sites. Indeed, recent reports suggest that halophyte species could be more suitable for heavy metal extraction than glycophytes most frequently used so far.

Plant physiology and biochemistry : PPB, 2017

It is well known that salinity reduces cadmium toxicity in halophytes. However, the possible inte... more It is well known that salinity reduces cadmium toxicity in halophytes. However, the possible interference of Cd with the mechanisms of salt tolerance is poorly explored. The aim of this study was to see whether Cd affects salt tolerance mechanisms in the halophyte Sesuvium portulacastrum. S. portulacastrum plants obtained from cuttings were grown in hydroponics for 3 weeks and then exposed to low (0.09 mM) or moderate (200 mM) NaCl concentrations, alone or in combination with 25 μM CdCl2. Microscopy observation revealed two strategies of salt tolerance: euhalophytism and secretion of salt by bladder cells. Cadmium exposure hardly influenced the total leaf Na(+) concentrations. However, Cd supply delayed the salt-induced upregulation of AHA1 (plasma membrane H(+)-ATPase 1) and SOS1 (plasma membrane Na(+) transporter "Salt Overly Sensitive 1"), genes that are essential for salt tolerance. Moreover, Cd induced the activation of BADH, coding for betaine aldehyde dehydrogenase,...

Chemosphere, 2017

The effects of inoculation with an arbuscular mycorrhizal (AM) fungus on Cd and Ni tolerance and ... more The effects of inoculation with an arbuscular mycorrhizal (AM) fungus on Cd and Ni tolerance and uptake in Medicago sativa, an AM host, and Sesuvium portulacastrum, a nonhost plant, were investigated in a greenhouse experiment. The plants were cultivated in sterilized sand in a two-compartmented system, which prevented root competition but enabled colonization of the whole substrate by AM fungal extraradical mycelium. M. sativa was either left non-inoculated or inoculated with the AM fungus Rhizophagus irregularis, and both plants were either cultivated without heavy metal (HM) addition or supplied with cadmium (Cd) or nickel (Ni), each in two doses. Additional pots with singly cultivated plants were established to control for the effect of the co-cultivation. AM significantly enhanced the growth of M. sativa and substantially increased its uptake of both HMs. The roots of S. portulacastrum became colonized by AM fungal hyphae and vesicles. The presence of the AM fungus in the cultivation system tended to increase the HM uptake of S. portulacastrum, but the effect was less consistent and pronounced than that in M. sativa. We conclude that AM fungal mycelium radiating from M. sativa did not negatively affect the growth and HM uptake of S. portulacastrum. On the contrary, we hypothesize that it stimulated the absorption and translocation of Cd and Ni in the non-host species. Thus, our results suggest that AM fungal mycelium radiating from mycorrhizal plants does not decrease the HM uptake of nonhost plants, many of which are considered promising candidate plants for phytoremediation.

Crop and Pasture Science, 2016

The effects of water deficit stress and recovery on growth, photosynthesis, physiological and bio... more The effects of water deficit stress and recovery on growth, photosynthesis, physiological and biochemical parameters were investigated in the cultivated Beta vulgaris and in two Tunisian provenances (Soliman and Enfidha) of its wild relative B. macrocarpa. Seedlings were cultivated for 4 weeks under optimal or limiting water supply (respectively, 100% and 25% of field capacity, FC). After 2 weeks of treatment, a lot of stressed plants were rehydrated to 100% FC. In the Control, B. vulgaris was more productive than B. macrocarpa, whereas Enfidha provenance showed the highest biomass production (1.6- and 3-fold compared with B. vulgaris and Soliman, respectively), under water deficit stress. A partial re-establishment of growth occurred in both species upon recovery at 100% FC. The sensitivity of B. vulgaris and Soliman provenance to drought was associated with the disturbance of leaf water status and the sharp decrease in net CO2 assimilation (–66% and –82% as compared with the Contr...

Planta, 2016

Main conclusion NaCl alleviates Cd toxicity in Sesvium portulacastrum by maintaining plant water ... more Main conclusion NaCl alleviates Cd toxicity in Sesvium portulacastrum by maintaining plant water status and redox balance, protecting chloroplasts structure and inducing some potential Cd 21 chelators as GSH and proline.

The Journal of Horticultural Science and Biotechnology, 2013

Ecotoxicology and environmental safety, Jan 30, 2015

Citrate, malate and histidine have been involved in many processes including metal tolerance and ... more Citrate, malate and histidine have been involved in many processes including metal tolerance and accumulation in plants. These molecules have been frequently reported to be the potential nickel chelators, which most likely facilitate metal transport through xylem. In this context, we assess here, the relationship between organics acids and histidine content and nickel accumulation in Mesembryanthemum crystallinum and Brassica juncea grown in hydroponic media added with 25, 50 and 100µM NiCl2. Results showed that M. crystallinum is relatively more tolerant to Ni toxicity than B. juncea. For both species, xylem transport rate of Ni increased with increasing Ni supply. A positive correlation was established between nickel and citrate concentrations in the xylem sap. In the shoot of B. juncea, citric and malic acids concentrations were significantly higher than in the shoot of M. crystallinum. Also, the shoots and roots of B. juncea accumulated much more histidine. In contrast, a higher...

Identification of an IRT-like gene implicated in cadmium accumulation in lettuce (Lactuca sativa)... more Identification of an IRT-like gene implicated in cadmium accumulation in lettuce (Lactuca sativa). Tunisian-Japanese Symposium on Society, Science and Technology

Biosaline Agriculture and Salinity Tolerance in Plants

... Chedly Abdelly1, Zouhaier Barhoumi1, Tahar Ghnaya1, Ahmed Debez1, Karim Ben Hamed1, Riadh Kso... more ... Chedly Abdelly1, Zouhaier Barhoumi1, Tahar Ghnaya1, Ahmed Debez1, Karim Ben Hamed1, Riadh Ksouri1, Ons Talbi1, Fethia Zribi1, Zeineb Ouerghi1, Abderrazzak Smaoui2, Bernhard Huchzermeyer3 and Claude ... According to Glenn and O&amp;amp;amp;amp;#x27;Leary [14] and Bayoumi et al. ...