The alleviating effect and mechanism of cold shock pretreatment (-2 ℃ cold air for 3 h) on flesh browning in fresh-cut pitaya fruit was explored by evaluating its effect on the phenylpropanoid pathway and antioxidant system during storage. Results revealed that cold shock pretreatment efficiently inhibited the increase in electrical conductivity and malondialdehyde (MDA) content compared with the control. Cold shock pretreatment promoted the gene expression and activities of key enzymes (phenylalanine ammonia lyase, cinnamic acid 4-hydroxylase, and 4-coumarate-CoA ligase) related to phenylpropane biosynthesis, and improved the accumulation of total phenolics and flavonoids, as well as most individual phenolic compounds, which led to enhanced antioxidant capacity. The activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were increased by cold shock pretreatment. In addition, cold shock pretreatment accelerated the production of superoxide anion and H₂O₂ at the early stage of storage, but had no effect on their peaks and led to lower levels of superoxide anion and H₂O₂ afterwards, alleviating flesh browning in fresh-cut pitaya fruit. These results indicated that cold shock pretreatment can effectively alleviate wound-induced oxidative stress by modulating the phenylpropanoid pathway and reactive oxygen species (ROS) metabolism, thus inhibiting flesh browning in fresh-cut pitaya fruit.

The APETALA2/ethylene-responsive factor (AP2/ERF) transcription factor family is one of the largest transcription factor families in plants. Its subfamily members activate or repress the expression of related genes by specifically binding to cis-acting elements such as the GCC box and DRE/CRT in the promoter regions of downstream interacting genes, and participate in the regulation of biological processes such as growth and development, maturation and senescence, and stress response in fruits and vegetables. In recent years, an increasing number of studies have shown that AP2/ERF can also regulate the quality and resistance of fruits and vegetables by regulating target genes and inducing various phytohormone responses such as ethylene, jasmonic acid and salicylic acid, or by acting as a response factor in response to phytohormone signals. This article provides an overview of the structural characteristics of AP2/ERF transcription factors and their classification and distribution in fruits and vegetables and reviews the latest research progress in the regulatory effect of AP2/ERF on stress resistance in fruits and vegetables through interaction with the major hormone signals. It is our hope that this review will provide a theoretical basis for enhancing stress resistance in fruits and vegetables from the perspective of hormonal regulation of AP2/ERF transcription factors.