Physiological and structural modifications in snail medic (Medicago scutellata L.) plants exposed to salinity.

Seeds of snail medic (Medicago scutellata L.) were assessed for their response to salt at the germination and seedling stages. NaCl at concentrations 86 and 170 mM decreased the final germination percentage. Embryonic axis length, water content and dry weight of embryonic axis and cotyledons were also reduced by salt treatment. Furthermore, 28-d-old plants were grown hydroponically with different NaCl concentrations (0, 86 and 170 mM). After 7 days of treatment, growth, water content and development of the different organs of M. scutellata plant were affected especially at the highest NaCl concentration (170 mM). However, NaCl did not affect root length and the number of stem shoots but reduced stem length and total leaf area. Salt treatment increased markedly the concentration of Na+ in leaf and root tissues while reduced that of K+ only in root and stem tissues. Lipid peroxidation revealed the damage of the membranes of roots and leaves. Moreover, showed a more intense suberization and lignification at the cambial zone of roots of M. scutellata, were observed under the effect of NaCl.

Comparison of the responses to NaCl stress of three tomato introgression lines.

We aimed to examine the response of three tomato introgression lines (IL925.3, IL925.5 and IL925.6) to NaCl stress. These lines originated from a cross between M82 (Solanum lycopersicum) and the wild salttolerant tomato Solanum pennellii, each line containing a different fragment of the S.pennellii genome. Salt-sensitive phenotypes related to plant growth and physiology, and the response of antioxidants, pigments and antioxidant enzymes were measured. In general, salt stress decreased the fresh weight of leaves, leaf area and leaf number and an increase of Na+ accumulation in aerial parts was observed, which caused a reduction in the absorption of K+ and Ca2+. Salt stress also induced a decrease in chlorophyll, carotenoids and lipid peroxidation (MDA) and an increase in anthocyanins and reduced ascorbate, although some differences were seen between the lines, for example for carotenoid levels. Guaiacol peroxidase, catalase and glutathione reductase activity enhanced in aerial parts of the lines, but again some differences were seen between the three lines. It is concluded that IL925.5 might be the most sensitive line to salt stress as its dry weight loss was the greatest in response to salt and this line showed the highest Na+ ion accumulation in leaves.

Comparison of antioxidant and antimicrobial activities of two cultivated Cistus species from Tunisia / Comparação das atividades antioxidante e antimicrobiana de duas espécies cultivada de Cistus da Tunísia

The secondary metabolite composition, antioxidant activities, and microbial inhibition properties of leaves of two Cistus species; C. monspeliensis and C. salvifolius were investigated using three solvent extracts (ethanol, hexane and distilled water). Ethanol extracts were most efficient at extracting phenolics, flavonoids and condensed tannins compared to hexane and distilled water for both Cistus species. A total antioxidant test (TAA) and two radical scavenging tests (DPPH and ABTS) indicated that the 70% ethanolic extract from C. salvifolius leaves had stronger antioxidant activity compared to the C. monspeliensis 70% ethanol extract, while the aqueous extract of C. monspeliensis was much stronger than the aqueous extract or the 70% ethanol extract of C. salvifolius. Overall, the polar extracts were more active in both species than the non-polar extracts. Thus aqueous ethanol extracts of the leaves of each Cistus species were tested for their ability to inhibit seven pathogenic microbial strains, including Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, and Candida albicans. Leaf ethanol extracts from both species were active against each microbial species, but the C. monspeliensis leaf ethanolic extract was much more active against several microbial species than that of C. salvifolius. For example, the C. salvifolius 70% ethanol extract showed its highest antimicrobial activity against P. aeruginosa and A. niger (MIC 3.1 mg/ml and MBC 6.3 mg/ml for both), while the C. monspeliensis extract showed much higher overall activity against E. coli, P. aeruginosa and C. albicana. (MIC 6.25 mg/ml and MBC 12.5 mg/ml for all three). In conclusion, maceration with 70% ethanol was the most efficient method for extracting total polyphenols, flavonoids, and condensed tannins from the two Cistus species, and the aqueous-ethanol extracts displayed the highest antioxidant and antimicrobial activities. Hence, the aqueousethanolic extracts of both species may be considered as potential sources of natural antioxidants and antimicrobial agents.

A composição de metabólitos secundários, atividade antioxidante e propriedades de inibição microbiana de extratos das folhas de duas espécies de Cistus; C. monspeliensis e C. salvifolius foram investigados utilizando-se três solventes de extração (etanol, hexano e água destilada). A extração com etanol foi a mais eficiente na extração de compostos fenólicos, flavonóides e taninos condensados em comparação com hexano e água destilada para ambas as espécies de Cistus. Um teste antioxidante total (TAA) e dois testes de eliminação de radicais (DPPH e ABTS) indicaram que o extrato em etanol 70% das folhas de C. salvifolius teve maior atividade antioxidante em comparação com o extrato etanólico de C. monspeliensis, enquanto o extrato aquoso de C. monspeliensis teve maior atividade antioxidante que o respectivo extrato aquoso ou o extrato etanólico de C. salvifolius. Em geral, os extratos polares foram mais ativos em ambas as espécies do que os extratos não-polares. Assim, extratos etanólico e aquoso das folhas de cada uma das espécies de Cistus foram testados quanto à sua capacidade de inibir sete cepas microbianas patogênicas, incluindo Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, e Candida albicans. Extratos etanólicos da folha de ambas as