Intermittent warming of peaches reduces chilling injury by enhancing ethylene production and enzymes mediated by ethylene

Peaches (Prunus persica 'Hermoza') were ripened at 20 degreesC after harves t and either stored at 0 degreesC for four weeks (control) to induce chilli ng injury or given intermittent warming (IW) on the twelfth day of storage (20 degreesC for 24 h) to alleviate chilling injury (CI). Continuously stor ed fruit from control developed woolliness, a Cl disorder, during ripening at 20 degreesC after cold storage while only a small percentage of IW fruit developed woolliness. CI fruit produced less ethylene during ripening afte r storage, and this inhibited ethylene production was closely tied with woo lliness development. The IW treatment caused enhanced ethylene production i n the fruit when returned to 0 degreesC and the ethylene remained higher th an control fruit until the end of the storage period. IW also induced the m essages for 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and 1-amino cyclopropane-1-carboxylic acid synthase (ACS) in the ethylene synthesis pat hway. IW also elevated the mRNA of the cell wall degrading enzymes polygala cturonase (PG) and endo-1,4-gluconase (EGase). The mRNAs of the cell wall e nzymes and the enzymes in the ethylene synthesis pathway remained higher ev en after 5 d at 0 degreesC following the IW treatment. It is suggested that IW maintained the fruit tissue capacity to ripen normally by preventing in hibition of the ethylene synthesis pathway which occurred in the control fr uit after extended storage.