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3 Acta Physiologiae Plantarum

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The effect of calcium on the antioxidant systems in the halophyte Cakile maritima under salt stress

100%

Amor N. B. , Megdiche W. , Jimenez A. , Sevilla F. , Abdelly C.

nr 3

The purpose of the current investigation was to study the effect of Ca²⁺ (0, 3.5 and 20 mM concentrations) on the antioxidant systems in the halophyte Cakile maritima under NaCl stress (0, 100, 200 and 400 mM NaCl). Plants treated with both moderate calcium (3.5 mM) and salt levels (100 mM) showed the maximum growth, and the addition of 20 mM calcium to the nutrient media did not significantly reduce the growth under the moderate salt treatment. The absence of calcium associated with high salt concentration induced a strong reduction of biomass production. The tolerance of C. maritima at moderate salinity and calcium was related with the lowest values of the parameters indicative of oxidative stress (malondialdehyde, electrolyte leakage and hydrogen peroxide concentration). This was accompanied with a higher peroxidase, superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase activities. In contrast, in the absence of calcium, those enzymes showed the lowest activities under all salt treatments. As a whole, it can be noticed that salt tolerance was improved by moderate calcium concentration; however, the absence of calcium has a drastic effect on C. maritima.

Variability of phenolic composition and biological activities of two Tunisian halophyte species from contrasted regions

86%

Trabelsi N. , Waffo-Teguo P. , Snoussi M. , Ksouri R. , Merillon J. M. , Smaoui A. , Abdelly C.

Acta Physiologiae Plantarum

2013

tom 35

nr 03

The present study consists in evaluating the inter- and intraspecific variability of phenolic contents and biological capacities of Limoniastrum monopetalum L. and L. guyonianum Boiss. extracts. Ultimately, they were subjected to HPLC for phenolic identification. Results showed a great variation of phenolic content as function of species and localities. In fact, L. guyonianum extracts (El Akarit) contained the highest polyphenol (57 mg GAE g-1 DW), flavonoid (9.47 mg CE g-1 DW) and condensed tannin contents (106.58 mg CE g-1 DW). These amounts were accompanied by the greatest total antioxidant activity (128.53 mg GAE g-1 DW), antiradical capacity (IC50 = 4.68 lg/ml) and reducing power (EC50 = 120 lg/ml). In addition, L. monopetalum and L. guyonianum extracts exhibited an important and variable antibacterial activity with a diameter of inhibition zone ranging from 6.00 to 14.83 mm. Furthermore, these extracts displayed considerable antifungal activity. L. monopetalum extracts (Enfidha) showed the strongest activity against Candida glabrata and C. krusei with a diameter exceeding 12 mm. The phytochemical investigation of these extracts confirmed the variability of phenolic composition, since the major phenolic compound varied as a function of species and locality. These findings suggest that these two halophytes may be a new source of natural antioxidants that are increasingly important for human consumption, as well as for agro-food, cosmetic and pharmaceutical industries.

Interactive effects of excessive potassium and Mg deficiency on safflower

72%

Farhat N. , Rabhi M. , Falleh H. , Lengliz K. , Smaoui A. , Abdelly C. , Lachaal C. , Karray-Bouraoui N.

Acta Physiologiae Plantarum

2013

tom 35

nr 09

In the present work, separate and combined effects of excessive potassium and magnesium deficiency on safflower (Carthamus tinctorius) were studied. Four treatments were considered: C (control treatment: complete medium containing 1.5 mM Mg), ?KCl (excessive potassium treatment: complete medium added with 60 mMKCl), -Mg (Mg-deficient treatment: containing 0.1 mM Mg), and DS (double stress treatment: Mg-deficient medium (0.1 mM Mg) added with 60 mM KCl. Excessive potassium effect on plant growth was more pronounced than that of Mg deficiency. The two stresses impaired differently plant organs; KCl application affected more roots than shoots, whereas Mg deficiency reduced only leaf biomass. Gas exchange and pigment concentrations and patterns were severely impaired by KCl and mainly by interactive effects of the two stresses. This led to obvious lipid peroxidation and electrolyte leakage. Mg deficiency did not induce lipid peroxidation and electrolyte leakage, but as applied with excessive potassium, it doubled the effect of the latter. Mineral analyses showed that major cation nutrition was disturbed by KCl and combined stresses and at a lower level by magnesium deficiency. Plants did not show an enhanced selectivity of Mg and Ca over K but they improved their use efficiencies.