关键词: 虎皮病, 活性氧, 6-甲基-5庚烯-二-酮, 梨

Abstract: Superficial scald is a physiological disease of pear that occurs during fruit storage. The peri-carp of the diseased pears is irregularly brownish, thus reducing the commercial value. In recent years, some studies have suggested that 6-methyl-5-hepten-2-one (MHO), a downstream product of the α-farnesene metabolic pathway, is likely to be a pathogenic factor of superficial scald. However, the mechanisms of MHO inducing superficial scald are unknown. In the present study, ‘Dangshansuli’ pear fruits were treated by MHO during cold storage. α-Farnesene, conjugated trienes, MHO, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide anion (O2·ˉ), and total phenols contents, and the enzyme activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and polyphenol oxidase (PPO) in the pericarp were measured. In addition, the development of superficial scald was observed and recorded. The results indicate that exogenous MHO can induce symptoms similar to superficial scald in ‘Dangshansuli’ pears. The exogenous MHO treatment had no significant effects on α-farnesene and conjugated trienes contents. Moreover, it significantly increased the MHO, H2O2 and O2·ˉ contents, and decreased the activities of antioxidant enzymes such as CAT, POD and SOD. MHO was more closely correlated with superficial scald than H2O2. In addition, the MHO content of diseased fruit was strongly correlated with H2O2 and O2·ˉ contents, respectively. These results reveal that MHO induces superficial scald by reactive oxygen species accumulation.

Key words: superficial scald, reactive oxygen species, 6-methyl-5-hepten-2-one, pear