Antioxidant Responses of Radiation-induced Dwarf Mutants of Bermudagrass to Drought Stress
2008
Lu, S. | Wang, Z. | Niu, Y. | Guo, Z. | Huang, B.
Improving the drought tolerance of widely used bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon] is important for water conservation and producing quality turf with limited irrigation. Mutants of bermudagrass were generated using gamma-ray irradiation with an aim toward developing dwarf and drought-resistant bermudagrass. The objectives of this study were to compare morphological characteristics between radiation-induced mutants and the wild-type of bermudagrass and to determine antioxidant responses associated with changes in drought resistance in the bermudagrass mutants. Three mutant lines (7-9, 10-5, and 10-12) that exhibit slow growth and good turf quality were chosen for this study. Plants were exposed to drought stress by withholding irrigation in a greenhouse. Mutant lines had lower canopy height, shorter internodes, and shorter leaves than the wild type under well-watered conditions. Under drought stress, all three dwarf mutant lines maintained higher relative water content and lower ion leakage and malondialdehyde content than the wild type. Antioxidant enzyme activities decreased in response to the drought stress in the mutant lines and the wild type, whereas nonenzymatic antioxidants increased under drought stress. Compared with the wild type, higher enzyme activities and antioxidant contents were maintained in mutant lines under drought stress. Our results indicated that bermudagrass mutants induced by gamma radiation exhibited dwarf characteristics and improved drought resistance, which was associated with maintenance of higher levels of antioxidant enzyme activities and nonenzymatic antioxidant contents.
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