采后GA_3诱导菠萝多酚氧化酶活性升高的机理

MECHANISM OF THE INCREASE OF POLYPHENOL OXIDASE ACTIVITY IN PINEAPPLE FRUIT INDUCED BY GA3

在多酚氧化酶（ＰＰＯ）提取过程中，直接加入ＧＡ３溶液，不能使ＰＰＯ活性增加。采后ＧＡ３诱导菠萝（Ａｎａｎａｓｃｏｍｏｓｕｓ（Ｌ．）Ｍｅｒ．）ＰＰＯ活性升高的同时，显著提高了酸性磷酸酯酶的活性，这是果实组织的Ｐｉ浓度明显升高的主要原因。随着果实的后熟，磷脂酶Ｄ活性不断下降，ＧＡ３处理显著延缓了该酶的下降速度。虽然采后ＡＢＡ处理使果实ＰＰＯ活性有小幅度增加，但ＡＢＡ处理能使ＧＡ３对ＰＰＯ活性的诱导明显加强。

No increase in polyphenol oxidase (PPO) activity was found by addition of GA3 solution in the enzyme extraction. But acid phosphatase activity was found to be increased in pineapple fruit (Ananas comosus (L.) Merr.) treated with GA3, which was mainly caused by the significant increase in inorganic phosphate (Pi) content. Phospholipase D activities decreased gradually during the period of fruit ripening but GA3 treatment slowed down these processes. On the other hand, the increase of PPO activities in fruit treated with GA3 was enhanced by the addition of ABA treatment.