Abdul Jabbar Al-Rajab

MAPK cascades and major abiotic stresses

Plants have evolved with complex signaling circuits that operate under multiple conditions and govern numerous cellular functions. Stress signaling in plant cells is a sophisticated network composed of interacting proteins organized into tiered cascades where the function of a molecule is dependent on the interaction and the activation of another. In a linear scheme, the receptors of cell surface sense the stimuli and convey stress signals through specific pathways and downstream phosphorylation events controlled by mitogen-activated protein (MAP) kinases and second messengers, leading to appropriate adaptive responses. The specificity of the pathway is guided by scaffolding proteins and docking domains inside the interacting partners with distinctive structures and functions. The flexibility and the fine-tuned organization of the signaling molecules drive the activated MAP kinases into the appropriate location and connection to control and integrate the information flow. Here, we overview recent findings of the involvement of MAP kinases in major abiotic stresses (drought, cold and temperature fluctuations) and we shed light on the complexity and the specificity of MAP kinase signaling modules.

Chemical composition, antibacterial and antifungal activities of Ruta graveolens L. volatile oils

Abstract The Ruta graveolens L. (Rutaceae) plant is used medicinally as a homeopathic remedy in various areas of the world. In this study, volatile oils were extracted from the areal parts of the plant which was collected from southern India, then investigated for its chemical constituents and antimicrobial activities. The volatile oils were extracted by hydrodistillation using a Clevenger apparatus and samples were simultaneously analyzed with GC and GC-MS. As a result, a total of 13 chemical constituents were characterized. Representing 100% of the total oil with 2-ketones are the major groups. The principal components were identified, undecanone-2 (43.66%), 2-nonanone (16.09%), 2-acetoxy tetradecanone (14.49%), and nonyl cyclopropanecarboxylate (9.22%), respectively. The extracted volatile oil showed antibacterial activity against gram-positive and gram-negative bacteria, resulting in a number of common human pathogenic bacteria including methicillin-resistant Staphylococcus aureus and the yeast Candida albicans. The zone of inhibition is from 12.57 ± 0.03 to 27.10 ± 0.02 mm. The minimum inhibitory concentration (MIC) values were within the antimicrobial activity range and varied between 0.70 ± 0.04 and 1.58 ± 0.05 μg/mL. The essential oil showed maximum antifungal activity (35.10 ± 0.02 mm) against Candida albicans. This study indicates that R. graveolens L. essential oils could be used as a natural medical application in antimicrobial and antifungal treatments.