1-Methylcyclopropene alleviates peel greasiness by regulating wax composition and microstructure of ‘Yuluxiang’ pears during storage

Abstract

The greasiness of ‘Yuluxiang’ pear rapidly increases following the transition from cold storage to ambient temperature storage, severely affecting the pear fruit’s appearance and commercial value. Therefore, it is important to develop new techniques to inhibit pear greasiness during storage. In this study, ‘Yuluxiang’ pears were subjected to a 24 h of fumigation with 1.0 μL L⁻¹ 1-methylcyclopropene (MCP). Subsequently, the pears were stored at 0 °C for 120 and 180 d, followed by a seven-day storage at 20 °C. Results showed that 1-MCP postponed the onset of peel greasiness. Moreover, it slowed the cracking of the pears’ cuticular wax layer and the exposure of crystal microstructure. At the same time, it inhibited the increase in the contents of (E)-β-famesene, α-farnesene, docosanol, stearic acid and hexadecanoic acid. 1-MCP suppressed the CO₂ and ethylene production rate (EPR) of the pears during the 120 d of cold storage and the subsequent seven-day storage at 20 °C. Correlation analysis found a positive correlation between EPR and the content of ester compounds in the peel wax. Thus, 1-MCP may inhibit the accumulation of wax compounds and EPR, thereby suppressing the occurrence of peel greasiness. Furthermore, molecular analysis showed that 1-MCP suppressed the upregulated expression of PyLACS9 and PyFAD2 throughout the storage period, and markedly inhibited the upregulated expression of the PyACO2 during the ambient temperature storage. Since PyLACS9 and PyFAD2 play crucial roles in regulating the extension and degradation pathways of fatty acids, it was suggested that 1-MCP may suppress the accumulation of wax components and the occurrence of greasy peel by inhibiting the up-regulated gene expression of PyACO2, PyLACS9 and PyFAD2.