ISHS Acta Horticulturae 425: II International Pineapple Symposium
MECHANISM OF BLACKHEART DEVELOPMENT INDUCED BY LOW TEMPERATURE AND GIBBERELLIC ACID IN PINEAPPLE FRUIT |
| Authors: | Z. Yu-Chan, T. Xing-Jie |
| Abstract:
Blackheart (BH, also known as endogenous brown spot or internal browning) is a physiological disorder in pineapple fruit induced by chilling temperatures or gibberellic acid (GA3). Factors causing the browning reaction, including polyphenol oxidase activity (PPO, EC 1.10.3.1), phenylalanine ammonia lyase activity (PAL, EC 4.3.1.5), phenolic compounds, and ethylene production, were tested in order to identify the involved biochemical pathways. The occurrence of BH in pineapple fruit was mainly due to the catalyzed oxidation of phenolic compounds by PPO to form a brown product. Low temperature or GA3 markedly increased PPO activity and the content of its substrates as catechol, chlorogalic acid and caffeic acid to accelerate the development of BH. The enhancement of PAL activity and dramatic increase in ethylene production induced by low temperatures or GA3 were also involved in the BH development. Higher levels of PPO, PAL activity and the phenolic compounds in the lower part than in the upper part of the fruit explained the initial BH symptom appearing at lower fruitlet bases near the core. | |
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