In Vitro Responses of Alfalfa Root (Medicago Sativa L.) to Salt stress and Melatonin

Alfalfa ( Medicago sativa L.) is the most cultivated forage legume. The growth and development of alfalfa roots are limited by salt stress. Growth regulator is an essential role of melatonin in plants, especially in root involved in stress tolerance. In this study, alfalfa roots under in vitro salt stress (150 and 200 mM NaCl) were pretreated with different concentrations of melatonin (0.1, 10 and 15 μM). principal component analysis to find out the best targets for melatonin and salinity. Exogenous utilization of melatonin in alfalfa roots significantly elevated the compatible solutes particularly glycin betaein (GB), soluble carbohydrate and K + content. Principal component analysis revealed that, Indol acetic acid (IAA) content, GB, flavonoids, carbohydrate and Na + were the best melatonin targets. Furthermore, salinity affected ROS, H 2 O 2 , O 2- , malondialdehyde ( MDA), phenylalanine ammonia-lyase (PAL), K + /Na + ratio and tyrosine ammonia-lyase (TAL) enzymes were augmented, and electrolyte leakage, Na + accumulation decreased in the saline medium.