Purpose To explore the effects of exogenous abscisic acid (ABA) on the antioxidant properties and cadmium (Cd) accumulation of tobacco under Cd stress.
Methods Using tobacco variety K326 as material, the ABA solution of four different mass concentrations (0, 50, 100, 150 mg/L) were sprayed on the tobacco leaf surface under Cd-stress (60 mg/kg). Subsequently, the activities of antioxidant enzymes and ascorbic acid (AsA)-glutathione (GSH) cycle key enzymes, and the Cd content of tobacco plants were measured.
Results Under Cd stress, the contents of malondialdehyde (MDA), AsA and GSH, and the activities of superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR) and ascorbate peroxidase (APX) in tobacco leaves were increased; the Cd content in the aboveground and underground of tobacco plants increased by 54.5 times and 31.5 times, respectively; the Cd transfer factor significantly increased by 69.23%. After spraying the ABA, compared with single Cd stress treatment, the MDA content, SOD activity, and POD activity were significantly decreased; the GSH content, APX activity, and GR activity first increased and then decreased with the increase of ABA mass concentration. Within 24 hours after ABA treatment, the AsA content increased sharply in 6-12 hours, the GSH increased sharply in 1-6 hours, and the contents of them decreased gradually or stabilized after 12 hours; the Cd content of tobacco plants decreased gradually with the increase of ABA mass concentration; the Cd bio-concentration factor and transfer factor were significantly lower than single Cd stress treatment.
Conclusion Spraying exogenous ABA can relieve oxidative damage of tobacco under Cd stress to a certain extent, and reduce the accumulation of Cd in the tobacco plants and its transport to aboveground. In this study, the treatment with 150 mg/L ABA is found to be the most effective in reducing Cd accumulation in tobacco plants.
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