Wax plays an important role in maintaining good appearance, quality and nutrients of fruits, delaying fruit senescence and prolonging fruit shelf life. As an important plant hormone, ethylene participates in stress signaling responses and regulates the process of fruit growth, development, ripening and senescence. At present, the pathway of fruit wax synthesis and transport has been gradually clarified, and the wax synthase and transporter genes involved in this pathway have been gradually identified and verified. The expression of these genes may be regulated by ethylene and the ethylene signaling system. Therefore, this review focuses on summarizing recent progress in research on the synthesis and regulation of fruit wax, ethylene regulation of horticultural crop fruit wax synthesis, and the regulatory effect of APETALA2/ethylene-responsive factors (AP2/ERFs) on fruit wax synthesis in model plants, agricultural crops and horticultural crops, in order to provide useful information for understanding the structural genes and AP2/ERFs transcription factors involved in regulating wax synthesis.

This study investigated the effects of 1-methylcyclopene (1-MCP) on the quality and volatile organic components (VOCs) of ‘Xiangshui’ pears during storage, and the expression of genes related to ethylene synthesis and the signal transduction pathway as well as aroma synthesis were determined by real-time polymerase chain reaction (PCR). Results showed that 1-MCP treatment significantly inhibited the decrease in fruit hardness and the increase in soluble solids content (SSC) (P < 0.05), suppressed the respiration rate and ethylene production rate, and reduced the number and amount of VOCs in the peel and pulp compared with the control group. Moreover, the expression of the ethylene synthesis genes ACS1 and ACO2, the ethylene receptor genes ETR2 and ERS1/2, the ethylene signal transduction gene EIN3, and the VOCs synthesis genes LOX1/6/8 and AAT1 were down-regulated in both the peel and pulp. Thus, 1-MCP can restrain the synthesis of VOCs and quality changes by down-regulating the expression of the ethylene synthesis and signal transduction genes and the expression of the LOX1/8 and AAT1 genes.

In order to prolong the storage period of ‘Huangguan’ pear and reduce the deterioration of fruit quality during long-term storage and subsequent shelf life, this study conducted preharvest treatment with different concentrations of aminoethoxyvinylglycine (AVG) to ‘Huangguan’ pear. Before and after refrigeration for 180 days and after subsequent shelf life for 7 days, quality indicators were tested. The results showed that compared with the control group, preharvest AVG treatment delayed the decline of fruit firmness, maintained higher contents of soluble solids and titratable acids, and effectively inhibited fruit surface browning and core browning, the most pronounced effect being observed at 200 mg/L AVG. During long-term cold storage, the contents of arbutin, chlorogenic acid and total phenols increased with the occurrence of core browning, and the activity of polyphenol oxidase (PPO) increased. The expression levels of PbPAL1, PbPAL2, PbPPO1, PbPPO5, PbLOX1 and PbLOX5 were up-regulated during cold storage, but down-regulated during shelf life. Preharvest treatment with 200 mg/L AVG significantly reduced the consumption of arbutin, chlorogenic acid and total phenols, inhibited the increase of PPO activity along with the expression of PbPAL1, PbPAL2, PbPPO1, PbPPO5 and PbLOX5, and thus effectively reduced core browning in ‘Huangguan’ pear .

Pear, one of the oldest fruit crops cultivated by humans, is widely consumed worldwide due to its sweet taste, juicy texture, and potential health benefit. Pears are commonly classified into European, Japanese and Korean, and Chinese pear varieties. Beyond being consumed fresh fruit, pear can be processed into dehydrated slice, canned product, wine, juice, paste, etc. In Traditional Chinese Medicine (TCM), pear fruit and its products have been used to treat fever, suppress cough, and quench thirst. Recent studies have found that pear is a rich source of bioactive compounds. This review compiles a table of the bioactive compounds in pear fruit, which contains 43 phenolic acids, 64 flavonoids, 24 triterpenoids, and 18 additional compounds. These bioactive compounds contribute to various health benefits, including anti-inflammatory, antioxidant, lung protection, hepatoprotective, anti-obesity, anti-diabetic, cardiovascular protective, anticancer, antimicrobial, skin lightening activities. The levels of bioactive compounds in pear fruit and its products vary with cultivar, fruit tissue, orchard management, postharvest storage, and processing factor. This review provides a comprehensive understanding of the health function of pear fruit and its products, and aims to increase the added value and promote further development of the pear industry.