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Sl-ERF.B.3 (Solanum lycopersicum ethylene response factor B.3) gene encodes for a tomato transcription factor of the ERF (ethylene responsive factor) family. Our results of real-time RT-PCR showed that Sl-ERF.B.3 is an abiotic stress responsive gene, which is induced by cold, heat, and flooding, but downregulated by salinity and drought. To get more insight into the role of Sl-ERF.B.3 in plant response to separate salinity and cold, a comparative study between wild type and two Sl-ERF.B.3 antisense transgenic tomato lines was achieved. Compared with wild type, Sl-ERF.B.3 antisense transgenic plants exhibited a salt stress dependent growth inhibition. This inhibition was significantly enhanced in shoots but reduced in roots, leading to an increased root to shoot ratio. Furthermore, the cold stress essay clearly revealed that introducing antisense Sl-ERF.B.3 in transgenic tomato plants reduces their cell injury and enhances their tolerance against 14 d of cold stress. All these results suggest that Sl-ERF.B.3 gene is involved in plant response to abiotic stresses and may play a role in the layout of stress symptoms under cold stress and in growth regulation under salinity.

This study was conceived to evaluate the essential fatty acids, secondary metabolites, antiradical and antimicrobial activities of unexploited Tunisian Ziziphus lotus L. The obtained results indicated that the major components of fatty acids were oleic acid (88.12%) and elaidic acid (7.88%). Leaves contained higher amount of total phenols, flavonoids and tannins than fruits, although both methanolic extracts had significant antioxidant activities. Significant correlations were observed between the total phenol or flavonoid contents in methanolic extracts and antioxidant activity estimated by using both 2,2'-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic radical-scavenging methods. In addition, both methanolic extracts exhibited strong antibacterial and antifungal activities. The inhibition zone diameters and the minimal inhibition concentration values were in the range of 10-17 mm and 3.1-50 mg/mL, respectively.

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