Exogenous melatonin application improves resistance to high manganese stress through regulating reactive oxygen species scavenging and ion homeostasis in tobacco

Melatonin (MT) can effectively improve the resistance of plants to various abiotic stresses. However, the effects of exogenous melatonin on the growth of tobacco plants under high manganese (Mn) stress condition are still largely unknown. In this study, growth inhibition, antioxidant activity, ion accumulation, as well as photoinhibition, in tobacco plants treated with high concentration of Mn and different concentrations of melatonin were investigated. Exogenous MT application significantly increased the resistance of tobacco plants to high Mn stress. Tobacco plants treated with various concentrations of MT showed less growth inhibition by high Mn stress, and accumulated less malondialdehyde (MDA) and hydrogen peroxide (H2O2), accompanied with a higher antioxidant enzyme activity and antioxidative gene expression. An altered ion accumulation, an increased metal related gene expression and a higher net photosynthetic rate (Pn) were also detected in tobacco plants treated with exogenous MT. Our observations indicate that exogenous MT application improved Mn tolerance in tobacco plants through the scavenging of reactive oxygen species (ROS) and the regulation of ion homeostasis.

Automated summary

Exogenous application of melatonin improves tobacco plant tolerance to high manganese stress by scavenging reactive oxygen species and regulating ion homeostasis.