低温与GA_3诱导菠萝黑心病的生理机制

菠萝黑心病是PPO催化氧化酚类物质形成褐色产物所致。低温或GA_3处理提高了PPO活性及其底物——儿茶酚、绿原酸和咖啡酸的含量,也导致了PAL活性增加;低温还使乙烯释放率增大。这些变化均有利于黑心病的发生和发展。

Mechanism of Blackheart Development Induced by Low Temperature and Gibberellic Acid in Pineapple Fruit

Blackheart, also known as endogenous brown spot or internal browning, is a physiological disorder induced by chilling or gibberellic acid (GA_3). It is enzymatic in nature. Factors causing browning, including polyphenol oxidase (PPO, EC 1.10.3.1) activity, phenylalanine ammonia-lyase (PAL, EC 4.3. 1.5) activity, phenolic compounds, and ethylene production, were assayed in order to identify the biochemical pathways related to the development of blackheart symptoms.The occurrence of blackheart in pineapple fruit is mainly due to the oxidation of phenolic compounds catalyzed by PPO to form brown products. Low temperature or GA_3 markedly increases PPO activity and the content of its substrates such as catechol, chlorogenic acid and caffeic acid and thus accelerates the development of blackheart.The enhancement of PAL activity and the dramatic increase in ethylene production induced by low temperature or GA_3 were also involved in blackheart development.