PJB-2018-20
ALLEVIATION OF SALT-INDUCED OXIDATIVE STRESS IN ALFALFA BY GLYCINEBETAINE
Yanhong Lou
Abstract
The objective of this study was to investigate whether the exogenous application of glycinebetaine (GB) could ameliorate the detrimental effects of salt on alfalfa (Medicago sativa L.). A hydroponic culture experiment was employed, and thirty-day-old alfalfa seedlings were subjected to 0, 5, 10, and 20 mM GB and exposed to a 1% salt regime, with a nutrient solution as the control. Salinity resulted in a remarkable decrease in the vertical shoot growth rate (VSGR), vertical root growth rate (VRGR), plant biomass, and normalized relative transpiration (NRT), with significant increases in themalondialdehyde (MDA), soluble protein content, and superoxide dismutase (SOD), catalase(CAT), and peroxidase (POD) activity. The application of GB increased VSGR, VRGR, and SOD activity and decreased the MDA, soluble protein content, and Na+/K+ ratio relative to the non-GB treatment. Alfalfa treated with 5 mM GB exhibited higher VSGR, VRGR, plant biomass, SOD, POD activity, and NRT and lower CAT activity when compared to other levels of GB application. Meanwhile, lower MDA and soluble protein contents were also observed in the 5-mM application treatment relative to the non-GB treatment. These results suggested that the GB-enhanced salt resistance in alfalfa was attributed to the elevation in SOD and POD activity and the decrement in the MDA and soluble protein contents. It could be concluded that the 5 mM GB application is the proper concentration to alleviate the adverse effects of salt on alfalfa.
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