冷藏和乙烯处理对采后苹果果实糖代谢及关键基因表达的调控

以富士和金冠苹果果实为试材，研究了冷藏和乙烯处理对其果实软化过程糖代谢及关键基因表达变化的影响。结果表明，随果实软化淀粉含量及淀粉酶（AM）活性的变化在品种间的差异显著，2 mL/L乙烯利和0.5 μL/L 1-MCP处理分别显著促进和抑制了MdAM基因的表达，在富士上表现在贮藏后期，而对金冠的影响则表现在贮藏前期，0 ℃冷藏均显著抑制了两品种果实MdAM的基因表达，表明淀粉降解参与了苹果果实的软化进程，显著受到低温和乙烯的调节。可溶性糖中，蔗糖含量显著增加，并显著受乙烯和低温的影响，其中SPS在采后果实糖代谢中的作用强于SS和AI，SPS活性和MdSPS基因表达亦显著受到乙烯利的促进和1-MCP的抑制，且对金冠的影响强于富士，低温下果实糖含量及酶活性变化较小，MdSPS基因表达显著受到抑制，表明蔗糖积累和SPS与采后苹果糖代谢和果实软化的关系较为密切。
‘Fuji’ and ‘Golden Delicious’ apple fruits were taken as material to study the sugar metabolism and the key enzyme gene expression during fruit softening and how they were affected by cold storage or ethylene treatment. The results indicated that the starch content and amylase (AM) activity showed the most significant changes between ‘Fuji’ and ‘Golden Delicious’ and were dramatically regulated by low temperature and ethylene. Accordingly, the expression of MdAM was significantly promoted by the treatment of 2 mL/L ethephon while inhibited by 0.5 μL/L 1-MCP treatment at the late stage of storage in ‘Fuji’ fruit or at the early stage of storage in ‘Golden Delicious’ fruit. Meanwhile the expression of MdAM was significantly inhibited under 0 ℃ storage in both cultivars. This suggest that post-harvest starch degradation involved in apple fruit softening and are significantly affected by cold storage and ethylene treatment. Among the soluble sugars, the sucrose content increased clearly and was significantly subjected to the regulation by ethylene and low temperature, and the SPS had much stronger effect on sugar metabolism in post-harvest apple fruit than those of SS and AI. The SPS activity and the expression of MdSPS were significantly promoted by ethephon treatment and inhibited by 1-MCP treatment in ‘Golden Delicious’ fruit. This phenomenon was stronger than that in ‘Fuji’ fruit during storage. Less variation was observed on the fruit sugars content and the enzyme activity under cold storage, and the expression of MdSPS was significantly inhibited. These indicated that sucrose accumulation and SPS may have more close correlation with fruit softening among the regulation of sugar metabolism.