superficial scald is a postharvest physiological disorder that occurs in pear during and
after cold storage. in this study, the superficial scald index; α-farnesene and its oxidation products,
conjugated trienols (ctols); phenolic content; and the expression of its related genes were investigated
in two different pear cultivars, ‘wujiuxiang’ (pyrus communis l.) and ‘yali’ (pyrus bretschneideri r.),
following 115 days of cold storage at 0 ◦c followed by 7 days of shelf life at 20 ◦c. the results
indicated that the superficial scald occurred after 115 days of cold storage and became more severe
during the shelf life of the ‘wujiuxiang’ pear, whereas no scald was observed in ‘yali’. the α-farnesene
levels increased rapidly at first and then decreased, while the ctols contents increased significantly
in ‘wujiuxiang’ as compared to ‘yali’, and the expression levels of the genes involved in α-farnesene
and ctols metabolism (hmgr1, hmgr2, gstu7, gpx5, and gpx6), as well as the phenolic synthesis (pal1, pal2, c4h1, 4cl2, c3h, and anr) of the peel, were significantly up-regulated at the
onset of the superficial scald. in addition, the relative conductivity and contents of catechin and
epicatechin were higher, and the expression level of the laccase gene (lac7) significantly increased
with the development of superficial scald, while lower contents of chlorogenic acid, arbutin, and
isorhamnetin-3-3-glucoside, as well as the lower expression levels of a phenolic-synthesis-related
gene (c4h3) and polyphenol oxidase genes (ppo1 and ppo5), were noticed in ‘wujiuxiang’ as
compared to ‘yali’. the results indicated that the onset and progression of superficial scald were associated with the accumulation of ctols, cell membrane breakdown, and higher catechin, epicatechin,
and rutin contents, as well as the expression of associated genes of the peels of pear fruit.