The role of ethylene in the prevention of chilling injury in nectarines

Woolliness is a chilling injury phenomenon occurring in nectarines held at low temperatures for extended periods. It is a disorder marked by altered c ell wall metabolism during ripening leading to a dry, woolly texture in the fruit. Two treatments were found to alleviate this disorder. One was holdi ng the fruits for 2 days at 20 degreesC before 0 degreesC storage (delayed storage) and the second was having ethylene present during cold storage (et hylene). Immediately stored fruit (control) had 88% woolliness while 7% of delayed storage and 15% of ethylene fruit showed woolliness. The severity o f the injury in individual fruits was closely related to inhibition of ethy lene evolution. Woolly fruit had higher levels of 1-aminocyclopropane-1-car boxylic acid (ACC) and less 1-aminocyclopropane-1-carboxylic acid oxidase ( ACO, EC 1.4.3) activity than healthy fruit. It is suggested that ethylene i s essential for promoting the proper sequence of cell wall hydrolysis neces sary for normal fruit softening. This is in contrast to chilling injury in other fruits, whereby ethylene is often a sign of incipient damage. Respira tion was also found to be associated with chilling injury, in that fruit wi th woolliness had a depressed respiration.