Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system

Guler, Neslihan Saruhan and Pehlivan, Necla (2016) Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system. Acta Biologica Hungarica, 67 (2). pp. 169-183. ISSN 0236-5383

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Abstract

Hydrogen peroxide (H₂O₂) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H₂O₂ 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 H₂O₂ 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 (H₂O₂) 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 H₂O₂ concentration. By contrast, exogenous low dose H₂O₂ improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H₂O₂ concentration was reduced by exogenous H₂O₂ as compared to drought treatment alone. H₂O₂ pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H₂O₂ pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H₂O₂ pre-treatment alleviated water loss and H₂O₂ content and increased drought stress tolerance by inducing the antioxidant system.

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