Internal browning of pineapple (Ananas comosus L.) fruit and endogenous concentrations of abscisic acid and gibberellins during low temperature storage

The relationship between internal browning (IB) and changes in endogenous abscisic acid (ABA), endogenous gibberellin (GA) [gibberellin A 1 (GA 1 ), gibberellin A 3 (GA 3 ) and gibberellin A 4 (GA 4 )] concentrations were investigated using pineapples ( Ananas comosus L. Merr; cv. Trad-see-thong and cv. Pattavia). The fruits were subjected to three different storage temperature conditions for 21 d: at 10 °C, 25 °C, or 10 °C with 1 d at 25 °C on either the 7th, 14th, or 21st day. In the fourth experiment, both cultivars were stored at 25 °C, but were treated with GA 3 or water (a control treatment) immediately before storage. In both cultivars, the polyphenol oxidase (PPO) activity was correlated with the degree of IB and was highest in fruit transferred from 10 °C to 25 °C. Endogenous ABA concentrations were significantly increased during storage at 10 °C and decreased after the fruit was transferred from 10 °C to 25 °C in both cultivars. In contrast, endogenous total GA (GA 1  + GA 3  + GA 4 ) concentrations were significantly increased after the fruit was transferred from 10 °C to 25 °C. Trad-see-thong pineapple, which had higher endogenous ABA during storage at 10 °C and higher GA concentrations after being transferred from 10 °C to 25 °C, showed a high IB incidence. In both cultivars, fruit treated with 433 μM GA 3 showed higher IB and PPO activity than untreated controls during storage at 25 °C. In addition, GA 3 application significantly increased the endogenous ABA concentration in the Trad-see-thong pineapple at 25 °C. The results suggest that endogenous ABA may be associated with the resistance response to IB in pineapples and GA concentrations may be factors that influence IB in pineapples.