脂氧合酶与猕猴桃果实后熟软化的关系

Lipoxygenase in Relation to the Ripening and Softening of ActinidiaFruit

２０ ℃下贮藏果实的脂氧合酶（ＬＯＸ） 活性随着后熟进程持续上升，其活性与果实硬度的变化呈极显著负相关，油酸、亚油酸和亚麻酸等不饱和脂肪酸的组分比例变化较大，而棕榈酸和硬脂酸等饱和脂肪酸的组分比例变化很小；０ ℃贮藏果实中的ＬＯＸ 活性被强烈抑制，果实后熟软化进程被明显延缓，５ 种脂肪酸组分比例变化均较平稳；外源乙烯处理显著促进了ＬＯＸ 活性的增加，加速了果实后熟软化进程。

Kiwifruit (Actinidia) was used to investigate the effects of different treatments on the changes of lipoxygenase(LOX) and fatty acids composition, and the relationship between LOX and ethylene production in ripening fruits so as to inquire into the role of LOX in the ripening and senescing of fruit. There was a negative relationship between the increase in LOX activity and decrease in fruit firmness in the fruits stored at 20℃; When fruit was stored at 0℃, LOX activity was markedly inhibited and its greatest activity was only 1/3.4 of that in the fruit stored at 20℃, the fruit ripening was delayed as well(Fig.1). The main fatty acids in ripening kiwifruit were palnitic(16∶0),stearic (18∶0) , oleic(18∶1), linoleic(18∶2) and linolenic (18∶3) acid. Significant changes in the unsaturated fatty acids did occur and no marked changes in the saturated fatty acids were observed in the fruits stored at 20℃, the proportions of linoleic acid(18∶2) and linolenic acid(18∶3) decreased in fruits stored for 5 d and then increased quickly while the proportion of oleic acid(18∶1) decreased; The fatty acid content did not change significantly in the fruits stored at 0℃(Fig.2). Exogenous ethylene treatment led to an increase in LOX activity and hastened fruit ripening when the fruits were stored at 20℃(Figs.3,4). The significance of these results is discussed, in terms of a role for LOX in the ripening of kiwifruit.