荔枝果实的糖积累与相关酶活性

Sugar Accumulation and Related Enzyme Activities in the Litchi Fruit of'Nuomici'and'Feizixiao'

以‘糯米糍’和‘妃子笑’两个品种为试材 ,对比研究两者在果实发育和成熟过程中假种皮中糖积累和转化及其与糖代谢相关酶类———酸性转化酶 (AI)、中性转化酶 (NI)、蔗糖合成酶 (SS)和蔗糖磷酸合成酶 (SPS)活性的关系。结果表明 :1.糯米糍荔枝以积累蔗糖为主 ,蔗糖 /还原糖比值约为1.5 ;妃子笑荔枝以积累还原糖为主 ,蔗糖 /还原糖比值仅约为 0 .4 ;2 .荔枝糖积累与库活力密切相关 ,但不同品种库活力的主要构成酶类不同 ,糯米糍主要是SS ,而妃子笑则主要是NI +SS ;3.不同的糖代谢酶活性决定了糖组分的不同 ,积累蔗糖为主的糯米糍具有高的SS和SPS活性 ,而转化酶活性较低 ;以积累还原糖为主的妃子笑的SS和SPS活性较低 。

Two litchi cultivars,'Nuomici'and'Feizixiao',were used to study sugar accumulation and transformatiom in aril,and the activities of enzymes involved in sucrose metabolism during their fruit maturation.In the aril of'Nuomici',more sucrose rather than reducing sugars was accumulated.The ratio of sucrose to reducing sugars was 1.5.In contrast,in'Feizixiao',more reducing sugars were accumulated and the ratio of sucrose to reducing sugars was 0.4.Sugar accumulation was closely related to sink activity,yet different cultivars showed different dominant enzymes.The dominant enzyme in the aril of'Nuomici'was sucrose synthase(SS),whereas in'Feizixiao',invertase and SS were found dominant.Different dominant enzymes in sucrose metabolism led to different sugar components in the aril sap.Absence of invertase but elevated activities of SS and sucrose phosphate synthase(SPS)led to predominantly accumulated sucrose in'Nuomici'.High activity of acid invertase and relatively low activities of SS and SPS led to the predominantly accumulated reducing sugars in'Feizixiao'.