Potential of ethylene in alleviating cold-induced volatile esters loss of ‘Nanguo’ pears by regulating the lipoxygenase pathway

Abstract

The storage period of ‘Nanguo’ pears (Pyrus ussuriensis Maxim.) can be effectively prolonged under low-temperature conditions. However, long-term refrigeration leads to the deterioration of fruit flavor and aroma through the loss of compounds such as volatile esters, resulting in lower commodity value of the stored fruit. In this study, the loss of ester was noted in fruit under long-term storage, evidenced by the reduced variety of esters, lowered contents of critical esters, and reduced total ester contents. Ethylene production was significantly lower in cold-stored samples than in samples without storage or with short-term storage. Linear regression analysis indicated that the loss of volatile esters induced by cold storage was related to low ethylene production. Exogenous ethylene treatment relieved the loss of esters, increased the types and content of esters, and improved the activities of enzymes involved in ester biosynthesis. Further analysis showed that ethylene production was promoted and that expression levels of key genes involved in ethylene signal transduction, including PuERS1, PuEIN4, PuEIN2, PuEIN3, and PuERF1, were upregulated in ET-treated fruit. Hence, it was concluded that the aroma quality of cold-stored ‘Nanguo’ pears can be improved by ethylene treatment due to the induced enhancement of ethylene biosynthesis and signal transduction.