Sugar Accumulation and Related Enzyme Activities in the Developing Mango Fruits cv.'Tainong 1'

The contents of starch,sucrose,glucose and fructose,the activities of amylase,sucrose metabolizing enzymes,including acid invertase(AI),neutral invertase(NI),sucrose synthase(SS) and sucrose phosphate synthase(SPS) during fruit development process were studied and the correlation between the sugar accumulation and the activities of enzymes were further analyzed in the fruit of mango cv.'Tainong 1'.The results showed that mango fruit growth was in a sigmoid curve.Starch,fructose and glucose accumulated sharply at the early stage of fruit development,while fructose and glucose slightly increased at the ripening stage.However,amylase activity dropped to minimize along with the starch decomposition and sucrose accumulated sharply at the ripening stage.The activities of acid invertase maintained higheer throughout the developmental stage,only dropped slightly at the ripening stage.The sucrose phosphate synthase dropped slightly at the early stage,then raised to the highest at the ripening stage.The activities of sucrose synthase and neutral invertase maintain minimize and changed very little throughout the development stages.The starch content had positive correlation with amylase,and significantly negative correlation with SPS.The contents of sucrose and glucose had significantly positive correlation with the activities of SPS and SS.The content of fructose had significantly positive correlation with SS.We deduced that a decomposition in starch,a reduction in acid invertase,an increment in SS and SPS activities were responsible for sucrose accumulation in developing fruits of mango cv.'Tainong 1'.