Taxifolin delays the degradation of chlorophyll in pakchoi (Brassica rapa L subsp. chinensis) by regulating the ascorbate-glutathione cycle

Abstract

The effects of taxifolin (TF) treatment on chlorophyll (Chl) degradation and the ascorbate-glutathione (AsA-GSH) cycle were evaluated in pakchoi. Compared with a control and other treatment concentrations, 1000 mg L−1 TF treatment had the greatest green retention effect on pakchoi. This treatment delayed the degradation of Chl and its derivatives and inhibited the activities of chlorophyllase, Mg-dechelatase, pheophytinase, and pheophorbide a oxygenase. The expression of Chl degradation (BrNYC1, BrNOL, BrCLH, BrSGR1, BrSGR2, BrPPH, BrPAO, and BrRCCR) and senescence (BrSAG12) related-genes was also suppressed, leading to better quality pakchoi. In addition, TF treatment alleviated decreases in total ascorbic acid, reduced ascorbic acid, dehydroascorbic acid, total glutathione, reduced glutathione, and oxidized glutathione, while enhancing the activities of ascorbic acid peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase. This contributed to maintained high free radical scavenging ability and lower membrane lipid peroxidation. These results demonstrate that TF can regulate the AsA-GSH cycle and maintain the activity to scavenge reactive oxygen species, thus reducing membrane lipid oxidation and ultimately reducing nutrient loss and Chl degradation in pakchoi.