Osmolyte mediated tolerance to water stress in Lepidium sativum L Brassicaceae

Abstract

newline ix newlineABSTRACT newlineAs the sessile nature, plants experience a diverse array of abiotic stresses during growth and development. Water stress is one of the most important abiotic stress factor that adversely affect growth, metabolism and yield of crops and medicinal plants throughout the world. The osmolytes are the compatible solute that is highly soluble compounds having low molecular weight are nontoxic at high concentrations. Osmolytes played pivotal role in plants for improving water stress tolerance. The objective of present study was to determine the effects of different osmolytes such as proline, glycine betaine and mannitol in response to water stress tolerance in Lepidium sativum L. This plant have various medicinal properties and it has been used for disease treatment like diarrhea, dysentery, skin, liver and renal disease, asthma, cough, cold, leucorrhoea, scurvy and so many diseases. It mainly contains alkaloids, saponins, glycosides, carbohydrates, proteins, amino acids, flavonoid as chief phytochemical constituents. The impact of proline, glycine betaine and mannitol in response to water stress on morphological, physiological, biochemical, nutritional, enzymatic and non-enzymatic antioxidant, secondary metabolites and radical scavenging effects were investigated in Lepidium sativum. Exogenous application of proline, glycine betaine and mannitol (50and#956;g/l, 100and#956;g/l, and 250and#956;g/l) were applied to plants grown under varied water potential of -0.01and#936;WMPa, -0.02and#936;WMPa, and -0.03and#936;WMPa. Morphological parameters (shoot and root length, shoot and root fresh and dry weight), physiological parameters (carbohydrate, protein, proline, relative water content, electrical conductivity, membrane stability index), biochemical analysis (lipid peroxidation), nutritional analysis (sodium and potassium), enzymatic antioxidant (CAT, POX, SOD, APX, GPX, GST), non-enzymatic (phenol, ascorbic acid, tocopherol, flavonoid, total chlorophyll), secondary metabolites (alkaloid, saponin, glycosides) and radical scavenging assay (ABTS, DPPH) were determined after 35, 55, 75, 95 and 110 days of proline, glycine betaine and mannitol application to the plants. Proline, glycine betaine and mannitol enhanced morphological, physiological parameters, nutritional factors, enzymatic and non-enzymatic antioxidant, secondary metabolites and radical scavenging assay in stressed plants, demonstrating that these played pivotal role to water stressed plants. From this study, it was concluded that proline, glycine betaine and mannitol was effective to cope plants to thrive under water stress conditions. However, it was observed that proline was more effective followed by glycine betaine and mannitol in non-stressed and stressed growing plants. newlineKeywords: Abiotic stress, Antioxidant, ABTS, Carbohydrate, Catalase, DPPH, Glycine betaine, Mannitol, Osmolytes, Peroxidase, Protein, Proline, Water stress.