Caffeic acid regulated respiration, ethylene and reactive oxygen species metabolism to suppress senescence of Malus domestica

The current study assessed the variations of reactive oxygen species (ROS), respiration and ethylene metabolism in ‘Qiujin’ apples after caffeic acid dipping. Results demonstrated that caffeic acid remarkably inhibited respiratory rate, ethylene release rate and hydrogen peroxide accumulation, but increased reduced glutathione and ascorbic acid contents in apples. Caffeic acid also improved catalase, peroxidase, superoxide dismutase, nicotinamide adenine dinucleotide phosphate oxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase and ascorbate peroxidase activities and gene expressions in apples. In addition, caffeic acid up-regulated MdG6PDH6 and MdAOX expressions, down-regulated MdACS1, MdACO2, MdPK, MdHK3, MdPFK, MdSDH and MdCCO expressions in the fruit. Taken together, caffeic acid could regulate the key enzymes activities and gene expressions in respiration, ethylene and ROS metabolism to suppress senescence of apples after harvest.