气调贮藏对苹果果实糖代谢的调控机制研究

田世平　朱竹

摘 要：糖是决定果实风味的关键物质。气调贮藏（CA）可以保持果实采后的品质。为研究气调贮藏对果实糖代谢的调控机制，该研究克隆了参与苹果果实糖代谢的多个基因，并研究了这些基因在不同貯藏条件下果实中的表达，及相关酶的活性变化。结果表明贮藏在CA条件下的苹果果实可以维持较高的糖含量，包括蔗糖、果糖和葡萄糖。一些关键基因例如蔗糖合酶（SS），蔗糖磷酸合酶（SPS），果糖激酶（FK）和己糖激酶（HK）的表达水平与酶活变化一致。在气调条件下中性转化酶（NI），液泡转化酶（VI），果糖激酶和己糖激酶的活性受到抑制，而蔗糖磷酸合酶的活性增强，表明CA可以增强蔗糖的合成，减少蔗糖和己糖的分解。上述结果为解释气调贮藏保持果实糖含量提供了分子水平的证据。

关键词：苹果 采后 糖代谢 气调

Abstract：Sugars are essential contributors to fruit flavour. Controlled atmosphere （CA） storage has been proved to be beneficial for maintaining harvested fruit quality. To explore regulatory mechanism of sugar metabolism in fruit stored in CA condition， we cloned several genes， encoding key enzymes， involved in sugar metabolism in apple fruit， and analyzed sugar contents， along with gene expression and enzyme activities in fruits stored in air and CA. The results indicated that CA could maintain higher contents of sugars， including sucrose， fructose and glucose. Expression levels of key genes， such as sucrose synthase （SS）， sucrose phosphate synthase （SPS）， fructokinase （FK） and hexokinase （HK）， were shown to be correlated with the corresponding enzyme activities. We found that activities of neutral invertase （NI）， vacuolar invertase （VI）， FK and HK were inhibited， but SPS activity was promoted in apple fruit stored in CA， suggesting that CA storage could enhance sucrose synthesis and delay hydrolysis of sucrose and hexose. These findings provided molecular evidence to explain why higher sugar levels in harvested fruit are maintained under CA storage.

Key Words：Apple； Postharvest； Sugar metabolism； Controlled atmosphere

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