Effects of Glycine Betaine and Drought Stress on Some Biochemical Traits of Mexican Lime Seedlings

Drought stress is one of the most important limiting factors for plant growth and productivity. Synthesis of glycine betaine in some plants has improved the tolerance to environmental stress. In this study, the effects of glycine betaine (0, 2.5, 5, 7.5, 10 mM) and four levels watering (100% FC, 75% FC, 50% FC, and 25% FC) were investigated on two-year old Mexican lime seedlings during two months. Following treatments, lipid peroxidation, electrolyte leakage, total protein, antioxidant capacity, peroxidase and superoxide dismutase activity were evaluated. Results showed that 7.5 and 10 mM treatments of glycine betaine prevented reduction of peroxidase activity during drought stress. In addition, 10 mM treatment of glycine betaine prevented significant loss of total protein. However, glycine betaine had no effects on some traits such as lipid peroxidation, electrolyte leakage, antioxidant capacity and superoxide dismutase activity. However, 50% FC level, increased antioxidant capacity. Content of malondialdehyde was added by low watering. This study shows that, glycine betaine at different concentrations could not enhance antioxidant capacity in seedlings while has protected proteins and may antioxidant enzymes such as peroxidase. This compatible solute has probably affected drought resistance through protection of some enzymes, substitution for water release and osmoregulation.