Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system
2016
Guler, Neslihan Saruhan | Pehlivan, Necla
Hydrogen peroxide (H ₂O ₂) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H ₂O ₂ in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H ₂O ₂ or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4 ᵗʰ and 7 ᵗʰ days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H ₂O ₂) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H ₂O ₂ concentration. By contrast, exogenous low dose H ₂O ₂ improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H ₂O ₂ concentration was reduced by exogenous H ₂O ₂ as compared to drought treatment alone. H ₂O ₂ pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H ₂O ₂ pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H ₂O ₂ pre-treatment alleviated water loss and H ₂O ₂ content and increased drought stress tolerance by inducing the antioxidant system.
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