Abstract: 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’.

Key words: Litchi chinensis Sonn., Fruit, Aril, Sugar accumulation, Invertase, Sucrose synthase, Sucrose phosphate synthase