Roles of Related Enzymes in Accumulation of Sugars in Nanguoli Pear Fruit

Using Nanguoli pear as experiment materials,the content of fructose,glucose,sucrose and the activities of related enzymes,including acid invertase(AI),neutral invertase(NI),sucrose synthase(SS),sucrose phosphate synthase(SPS) and amylase during fruit process were measured,and the correlation between the sugar accumulation and the enzymes activities was analyzed in the fruit of Nanguoli pear.The results showed that the Nanguoli pear fruit growth was in a sigmoid curve.Fructose and glucose were accumulated sharply at first and middle of second stages,and sucrose was not accumulated,which were related to high invertase activities.The activities of acid invertase and neutral invertase were higher at the early stage than that at the late stage;the activitives of sucrose synthase and sucrose phosphate synthase had similar patterns and showed 'V' trend.Before the ripening stage,sucrose was accumulated sharply.Roles of many enzymes resulted in accumulation of sugars,acid invertase and neutral invertase was restriction enzyme in accumulation of sugars.Sugars began to be accumulated when the acid invertase,neutral invertase activities disappeared and sucrose synthase,sucrose phosphate synthase activities increased;Amylase activities increased with rapid growth of fruit,and decreased before the ripening.