Influence of long-term cold storage on phenylpropanoid and soluble sugar metabolisms accompanied with peel browning of ‘Nanguo’ pears during subsequent shelf life

Abstract Cold storage can effectively postpone the senescence of postharvest ‘Nanguo’ pear fruit. However, peel browning (PB) usually develops after the fruit are transferred to shelf life at room temperature. In this study, influence of cold storage on phenylpropanoid and soluble sugar metabolisms accompanied PB in pears was investigated. Increased PB and decreased phenolics compounds were observed with the extension of cold storage. The activities and genes expression levels of enzymes involved in phenylpropanoid metabolism were restrained by long-term cold storage. Meanwhile, lower content of sucrose and sorbitol, and higher content of fructose and glucose were detected as the prolonging of storage time, accompanied by decreased activities and genes expression levels of sucrose synthase (SS) and sucrose phosphate synthase (SPS), and increased activities and genes expression levels of invertase. The results showed that the occurrence of PB in pears after long-term cold storage was closely related to phenylpropanoid and soluble sugar metabolisms, and the possible mechanisms are discussed.