Role of sucrose metabolism related enzymes in accumulation of sugar in‘Shixia'of Dimocarpus longan Lour.

【Objective】To ascertain the relationship between accumulation of sugar and sucrose-metabo-lism related enzymes.【Methods】The contents of sucrose,glucose and fructose in longan aril were mea-sured by HPLC,and the activities of related enzymes were measured by spectrophotography.【Results】The results showed that the trend of fruit weight,aril weight and total sugar were from slow to fast. Glu-cose and fructose accumulation were mainly mediated by AI and SS(the decomposition direction)in theslow growth period of aril. The sucrose accumulation was mainly mediated by decreasing activities of AIand SS(the decomposition direction)and rising activities of SS(the composition direction)and SPS. How-ever,the activity of NI was relatively lower.【Conclusion】'Shixia'belonged to the sucrose accumulationtype. There were two obvious turning points of the sucrose accumulation(70 d after flowering)and the netactivity change of related enzymes(65-75 d after flowering) in the process of the aril growth. With the su-crose accumulation,the activities of AI and SS(the decomposition direction)were descendant and SS(thecomposition direction)and SPS were rising. So the accumulation of sugar was controlled by a variety of en-zymes together.