Effects of Methyl Jasmonate on Physiological Characteristics and Drought Resistance of Alfalfa (Medicago sativa) and Ryegrass (Lolium perenne L.)

Methyl jasmonate (MeJA) plays a vital role in plant tolerance against various abiotic and biotic stresses. In this study, the function and mechanism of MeJA in drought resistance of alfalfa (Medicago sativa) and ryegrass (Lolium perenne L.) were investigated. The results revealed that MeJA significantly enhanced plant growth, the shoot dry mass of alfalfa and ryegrass increased by 17.01% and 16.10%, respectively, and the root dry mass increased by 24.50% and 60.41%, respectively. DAB and NTB staining revealed the drought-induced oxidative stress was significantly alleviated by MeJA. The root vitality was increased and the electrolyte leakage decreased, meanwhile, the stress alleviation was accompanied by the increased relative water content, increased stomatal aperture, and higher accumulation of the photosynthetic pigments. The content of the soluble protein and proline was decreased in MeJA + D treated plants as compared to drought-treated plants, and the activity of the antioxidant enzymes (POD, CAT, and APX) was modulated. Besides, MeJA increased the level of endogenous IAA and MeJA in both plant species under drought stress, which contributed to the higher biomass and better drought resistance. The leaf anatomical structure of both alfalfa and ryegrass was modulated by MeJA under drought stress. Overall, this study suggested that MeJA could be employed to improve the drought tolerance of alfalfa and ryegrass in arid and semi-arid areas. [GRAPHICS] .