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 (1B) 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 degrees C, 25 degrees C, or 10 degrees C with 1 d at 25 degrees C on either the 7th, 14th, or 21st day. In the fourth experiment, both cultivars were stored at 25 degrees 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 degrees C to 25 degrees C. Endogenous ABA concentrations were significantly increased during storage at 10 degrees C and decreased after the fruit was transferred from 10 degrees C to 25 degrees 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 degrees C to 25 degrees C. Trad-see-thong pineapple, which had higher endogenous ABA during storage at 10 degrees C and higher GA concentrations after being transferred from 10 degrees C to 25 degrees C, showed a high IB incidence. In both cultivars, fruit treated with 433 mu M GA(3) showed higher IB and PPO activity than untreated controls during storage at 25 degrees C. In addition, GA(3) application significantly increased the endogenous ABA concentration in the Trad-see-thong pineapple at 25 degrees 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. (C) 2012 Elsevier B.V. All rights reserved.