Abstract

p -CA markedly promotes anthocyanin accumulation and enhances juice color in fruit. • p -CA treatment enhances total flavonoids and its main components in blood orange. • p -CA increases TSS/TA contents, reduces fruit weight loss and MDA level. • p -CA activates PAL/C4H/4CL and SOD/CAT/APX activities to maintain ROS homeostasis. • C2H2-ZF and AP2/ERF are key regulators involved in anthocyanin accumulation. Anthocyanin content determines the nutritional and colour quality of blood orange. This study examined effects of p -coumaric acid ( p -CA) on anthocyanin accumulation and storage traits of blood orange. Compared with control, p -CA significantly accelerated anthocyanin accumulation, and increased juice colour index and anthocyanin content. Total flavonoids and its components (flavanol, flavonol, flavanone, flavone) were also elevated. p -CA-treated fruit had higher titratable acid (TA) and total soluble solids (TSS), and lower weight loss. The treatment enhanced superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) activities, 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) scavenging ability, hydrogen peroxide (H 2 O 2 ) and superoxide anion (O 2 − ·) contents, while reducing malondialdehyde (MDA) content. It also increased phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H) and 4-coumarate: CoA ligase (4CL) activities. Transcriptomic analysis showed ethylene-responsive transcription factor (AP2/ERF) and C2H2-type zinc finger (C2H2-ZF) were significantly correlated with anthocyanin content. This study provides a safe and effective technique to improve postharvest quality of blood orange.