The effects of increasing salinity levels on Sulla carnosa photosynthesis are mainly of stomatal nature

Sulla carnosa Desf. plants were subjected to 0, 100, 200, and 300 mM NaCl for 40 days. Leaf and stem growth as well as root and leaf water contents were not affected even at 300 mM NaCl, confirming the halophytic nature of this species. An accumulation of Na+ in roots and at a higher magnitude in leaves together with a decline in K+ concentrations suggest that Na+ involvement in osmotic adjustment as a cheap osmoticum. This typical halophytic response together with the reduced transpiration rate by stomata closure may explain the ability of S. carnosa to maintain its water status. Interestingly, the stomatal limitations of photosynthetic activity did not affect Fv/Fm, F0, and PSII energy distribution to photochemical process [Y(II)], regulated non-photochemical quenching [Y(NPQ)], and non- regulated non-photochemical quenching [Y(NO)], which suggests a high ability of this halophyte to cope with the energy expected to exceed the demand for its photosynthesis

Cynanchum Acutum L: Phytochemical Screening, Allelopathic and Cyto/Genotoxicity Effects in the Plant Model Arachis Hypogaea

Abstract The plant Cynanchum acutum L. growing in the Algerian desert is a weed a climber, but it has been used in popular medicine. This plant is rich in biologically active compounds, so it can be valued and exploited to produce specific biopesticides. In this regard, the work aims to assess the allelopathic effect of the aqueous extract of the air part of Cynanchum ActumL through phytochemical screening, where the results showed that the plant contained (coumarins, ,saponins polyphenols, flavonoids, alcaloids, terpenes,tannins, quinones, aldehydes, and cardioglycoside ). Four levels of concentration were tested (control,15mg/ml, 30mg/ml and 45mg/ml) where the extract affected negatively on all indicators of germination and initial development of Arachis hypogaea L. And their value decreased linearly until it disappeared at a concentration of 45 mg/ml, and the percentage of inhibition linearly increased until it reached 100% at concentration 45 mg/ml with statistically significant differences recorded. This confirms the existence of an inhibition process that was confirmed by the microscopic study to detect the cytotoxicity of the seeds of Arachis hypogaea L. Treatment with an aqueous extract with a concentration that inhibits root growth 50%, which was extracted from the root growth equation, which showed a decrease in the mitotic index with the observation of chromosomal abnormalities such as (the beginning of the formation of 2 micronucleus at interphase, micronucleus at interphase, binucleated cells at interphase, disturbed at metaphase, stickiness at metaphase, oblique at metaphase, fragments at metaphase, bridge at anaphase, and binucleated cells diagonal)

Alfalfa crops amended with MSW compost can compensate the effect of salty water irrigation depending on the soil texture.

The availability of water resources of marginal quality such as drainage water or high-saltcontaining groundwater is turning into an important issue in Tunisia and other countrieswith scarce water resources. A pot experiment was carried out to evaluate plant produc-tion, nutrient content and heavy metal bioaccumulation in agricultural soils amended withMSW compost and irrigated with salty water, by using two different soil textures (clay andsandy). Salt water supply decreased plant dry yield in both soils. Salt stress had signifi-cantly reduction in plant biomass in sandy soil compared to those in clay soil (biomass ofdry weight is significantly higher in clay soil than those in sandy soil in presence of salt:percentage of growth compared to control was 55% for clay soil and 45% for sandy soil).The application of Municipal Solid Wastes (MSW) Compost increased significantly alfalfaproductivity in both soils (Dry weight is significantly higher in presence of compost: 140%for clay soil and 125% for sandy soil). In non-amended soil, the growth was reduced signifi-cantly by salt stress (50% in clay soil, 26% in sandy compared to the soils without salty waterapplication). Plants irrigated with salty water accumulated much more sodium on sandysoil (1.74 mmol g−1) than on clay one (0.87 mmol g−1DW). Compost did not reduce sodiumaccumulation in aerial parts on sandy soil, whereas it slightly reduced it in those grownon clay soil. Zinc (Zn), Copper (Cu), Lead (Pb) and Cadmium (Cd) concentrations showedthe same trend for both soil types. They increased statistically significant by salinity to124-189%, the highest rise was found in Cu concentration on clay soil. The order of metaluptake was: Zn > Cu > Pb > Cd. A higher significant shoot accumulation of heavy metals (upto 305% of the control) was noticed in the presence of compost with no difference betweensalt-treated and non-treated. MSW compost amendment caused an increase of the studiedheavy metals in alfalfa shoots grown that was higher on sandy soils than clay soils. Heavymetals in plants remained lower than phytotoxic level and these level of accumulation did not restrain the enhancement of alfalfa yield. MSW compost at 40 t ha−1was convinent todo not attend phytotoxic level. These results suggest that MSW compost compensates, atleast partially, the negative effect of salinity on plant growth and nutrient uptake and thatit is important to know soil texture to apply compost to remediate salty degraded soils.© 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Presence of proline in salinized nutrient solution re-enforces the role of this amino acid in osmoregulation and protects lipid membrane peroxidation in Arabidopsis thaliana

Abstract Very little is known about the effect of proline addition on the accumulation of inorganic solutes (Na ) and soluble sugars in the model plant Arabidopsis thaliana. Therefore, the aim of the present study was to assess the effect of 10 mM proline (P) supply in the culture medium on water status and solute accumulation of Arabidopsis thaliana seedlings exposed to 50 mM NaCl (S). The decrease of leaf osmotic potential was more pronounced in P+S as compared to S plants, indicating that former plants were able to accumulate more compounds involved in the osmotic adjustment process. Leaf potassium concentration was reduced by 15, 21 and 25% in P, S and P+S plants respectively, as compared to the control. When compared to S or P treatments, leaf proline and soluble sugar were more accumulated under P+S treatment. Under saline conditions, exogenous proline increased leaf Na + , Ca 2+ and Mg 2+ concentrations by 27, 281 and 252%, respectively, as compared to the control. Interestingly, proline addition mitigated significantly the deleterious effects of salt on lipid membrane peroxidation. Regarding the contribution of soluble sugars to osmotic adjustment (OA), it amounted to 6% in S or P+S, plants. For proline, its contribution to OA did not exceed 3.4% under salinity (S), whereas in (P+S) treatment, it increased to 14.7%. As a whole, the positive effect of proline exogenous application under saline conditions could be partly explained by the enhanced role of this organic compound in osmoregulation and its likely protective effect against membrane lipid peroxidation

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

Brackish Water Phytodesalination by the Euhalophyte <i>Sesuvium portulacastrum</i>

In the Middle East and North Africa as well as in numerous countries in South America and Southeast Asia, water scarcity is a real concern. Therefore, water desalination has become a key solution and an important source of freshwater production. Solar stills are used for water desalination but they require low depth of sea or brackish water and sufficient solar radiation to evaporate water. In this investigation, a phytodesalinator is presented for the first time. The halophyte used in this work is Sesuvium portulacastrum L., a heat-tolerant euhalophyte. The presented phytodesalinator can replace basic solar stills during cold seasons if there is sufficient sunlight to ensure the transpiration process in the plant. The euhalophyte S. portulacastrum was tested for its ability to desalinate reject brine as grown for two subsequent phytodesalination cycles. Several factors were found to affect the productivity of the phytodesalinator, in particular, solar radiation, phytodesalination duration, and plant density. Nevertheless, it exhibited an average productivity of 2.44 kg/m2/d and showed several advantages in comparison with basic solar stills

The halophyte Cakile maritima reduces phenanthrene phytotoxicity

International audienceIn a previous study, we showed that the halophyte plant model Thellungiella salsuginea was more tolerant to phenanthrene (Polycyclic Aromatic Hydrocarbon: PAH) than its relative glycophyte Arabidopsis thaliana. In the present work, we investigated the potential of another halophyte with higher biomass production, Cakile maritma, to reduce phenanthrene phytotoxicity. Sand was used instead of arable soil with the aim to avoid pollutant degradation by microorganisms or their interaction with the plant. After 6 weeks of treatment by 500 ppm phenanthrene (Phe), stressed plants showed a severe reduction (-73%) in their whole biomass, roots being more affected than leaves and stems. In parallel, Guaiacol peroxidase (GPX) activity was increased by 185 and 62% in leaves and roots, respectively. Non-enzymatic antioxidant capacity (assayed by ABTS test) was maintained unchanged in all plant organs. The model halophytic plant Thellungiella salsuginea was used as a biomarker of phenanthrene stress severity and was grown at 0 (control), 125, 250, and 375 ppm. T. salsuginea plants grown on the sand previously contaminated by 500 ppm Phe then treated by C. maritma culture (phytoremediation culture) showed similar biomass production as plants subjected to 125 ppm Phe. This suggests that the phytotoxic effects of phenanthrene were reduced by 75% by the 6-week treatment by C. maritima. Our findings indicate that C. maritima can constitute a potentially good candidate for PAH phytoremediation

The halophytic model plant Thellungiella salsuginea exhibited increased tolerance to phenanthrene-induced stress in comparison with the glycophitic one Arabidopsis thaliana: Application for phytoremediation

International audiencePolycyclic aromatic hydrocarbons constitute a large family of organic environmental pollutants. Hence, a particular attention has been attributed to all approaches involved in the reduction of their contamination in water and natural ecosystems. Plant tolerance, absorption, accumulation, and likely biodegradation of these pollutants, known as phytoremediation, have emerged as an efficient technique to remediate environments contaminated with polycyclic aromatic hydrocarbons. The present work was aimed to compare the tolerance to phenanthrene (a polycyclic aromatic hydrocarbon) in the two model plants: Arabidopsis thaliana (glycophyte) and Thellungiella salsuginea (halophyte). Our study showed that the development of these two species was reduced under phenanthrene stress, the effect being more pronounced in A. thaliana than in T. salsuginea. In parallel, results from the intrinsic quantum yield of photosystem II and chlorophyll concentrations were concomitant with those of growth and phenotypic changes, and confirmed the higher tolerance of T. salsuginea compared to that of A. thaliana. The intrinsic quantum yield of photosystem II was drastically decreased in the glycophyte, which indicates a marked disturbance in photosystem II performance. This induced a severe oxidative stress as shown by the utilization of specific reactive oxygen species probes. In parallel, the activities of glutathione reductase, gaiacol peroxidase, and superoxide dismutase were increased by 95, 73, and 36%, respectively, which indicates a marked phenanthrene-induced oxidative stress. In T. salsuginea, photosystem II performance was not significantly affected. This species showed less accumulated reactive oxygen species than A. thaliana. Its enzymatic antioxidant system showed few changes as superoxide dismutase was the only enzyme whose activity was enhanced (+34%). A much higher capacity of recovery was also noticed in this halophyte as compared to the glycophyte. Indeed, it seems that T. salsuginea accumulated phenanthrene in stomata, which suggests its possible volatilization. All these data, taken together, add new insight to the mechanisms involved in halophytic plant tolerance to abiotic stresses and their potential use inphytoremediation