Crop Plant Hormones and Environmental Stress

Abstract

Plant hormones play vital roles in the ability of plants to acclimatize to varying environments by mediating growth, development and nutrient allocation. Hormones move through specific pathways to regulatory sites where they respond to stress at awfully low concentration. All biological activities are directly or indirectly affected by both phytohormones. Here we review the role of hormones against abiotic tolerance in crop plants. The main findings are: (1) abscisic acid act as a mediator in plant responses to many stresses, including salt stress. (2) Stress modifies the level of indole acetic acid (IAA) thus reducing growth. (3) Functional analysis of cytokinin receptor mutants show that cytokinin receptors of Arabidopsis act as negative regulators in abscisic acid (ABA) signaling and in osmotic stress response. (4) The mechanisms by which gibberellic acid (GA) priming could induce salt tolerance in plants are not yet clear. Salinity perturbs the hormonal balance in plants. Under salt stress hormonal homeostasis might be the possible mechanism of GA3-induced plant salt tolerance. (5) A low level of salicylic acid and jasmonate is effective against abiotic stress by enhancing physiological processes and improving tolerance. (6) Role of brassinosteroids and triazole during environmental stress is emerging. (7) Ethylene is considered as a stress hormone; however, the role of ethylene in salt stress is equivocal. The present review focus on abscisic acid, indole acetic acid, cytokinins, gibberellic acid, salicylic acid, brassinosteroids, jasmonates, ethylene and triazole.