Red LED irradiation maintains the postharvest quality of broccoli by elevating antioxidant enzyme activity and reducing the expression of senescence-related genes

The quality of broccoli stored at ambient temperatures deteriorates rapidly as tissues begin to senesce. The effect of red light-emitting-diode (LED) light irradiation (50 mu mol m(-2)s(-1)) on the quality of harvested broccoli stored at 20 degrees C for 5 d was investigated. Sensory quality and physiological function, including the activity of antioxidant enzymes and the expression of genes associated with chlorophyll degradation, were analyzed. Results indicated that red LED irradiation maintained the sensory appearance of broccoli, inhibited yellowing and the degradation of chlorophyll, and decreased weight loss and malondialdehyde (MDA) content. The activity of the antioxidant enzymes, peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were enhanced in LED-treated broccoli, while the expression of the chlorophyll degrading genes, chlorophyllase II (BoCLH2), chlorophyllase III (BoCLH3), and pheophorbide a oxygenase (BoPAO) was suppressed in the early stages of storage. In contrast, no effect on chlorophyllase I (BoCLH1) was observed. These results demonstrated that irradiation of broccoli with red LED induced a series of physiological and molecular responses that extended postharvest quality and could be used to prolong the shelf-life of commercially produced broccoli.