ROLE OF SUGARS, AMINO ACIDS AND ORGANIC ACIDS IN IMPROVING PLANT ABIOTIC STRESS TOLERANCE

Plant growth and development are affected by many environmental factors. Among them, abiotic factors such as drought and salinity are more destructive; and responsible for worldwide crop losses. These stresses are also responsible for several biochemical and physiological changes in the plants. During metabolomic profiling, it was confirmed that sugars, amino acids and amines are accumulated in different plant species under abiotic stress condition. In most plant species, sugars are considered as the major contributing factor in osmotic adjustment. Soluble sugars are very important in various metabolic events, work as a signal to regulate different gene expression that are involved in photosynthesis, osmolyte synthesis and sucrose metabolism. It was suggested that the accretion of amino acids helps in stress tolerance of plants; through contributing in detoxification of reactive oxygen species, regulation of pH and osmotic adjustments. Among all organic acids, especially succinic, malic and galacturonic acids increase the plant response to long-term drought stress. Amphoteric quaternary amines such as glycine betaine regulate water balance between a plant cell and the environment by stabilizing macromolecular structure and activity. Metabolomic analysis of sugars, amino acids and organic acids is an important tool to correlate the metabolic changes with plant responses. This review aims to explore how sugars, amino acids and organic acids assist plants under severe environmental conditions and alleviate the adverse effects of abiotic stresses.