ABSTRACT
Stress in plants refers to external situations that adversely affect the growth, progress or productivity of plants. It is of two types, biotic stresses which are caused by living organisms such as insects, weeds, and abiotic stresses such as drought, temperature extremes, salinity and nutrient imbalances which are caused by environmental impacts. Both types of stresses and diseases cause considerable reductions in crop productivity. The Moringa (Moringa oleifera L.) tree is drought tolerant, but salinity stress causes over-production of reactive oxygen species (ROS) in plant tissues. A balance between the generation and degradation of ROS is essential to avoid oxidative damage and to continue metabolic roles under stress conditions. The application of salicylic acid (SA) has been shown to improve plant stress tolerance, while ethanol extracts of Moringa and also the presence of some crystalline alkaloids, fatty acids, proteins, peptides, glycosides and niazirins in Moringa leaves have shown strong antifungal activities in vitro against many pathogenic fungal strains. Also, a number of motifs associated with abiotic stress response in plants in the promoter regions of MolHSF genes and transcriptional factors of micro-RNAs have a role in the plant’s response to abiotic and biotic stresses.
