The contents of sucrose, glucose, fructose and sorbitol, the activities of sucrose-metabolizing enzymes,including acid invertase (AI),neutral invertase (NI),sucrose synthase (SS) and sucrose phosphate synthase (SPS) during fruit development process were investigated and the correlation between the sugar accumulation and the activities of enzymes were further analyzed in the fruit of pear ‘Cuiguan’, ‘Cuiguan’bagging, ‘Whangkeumbae’ and ‘Whangkeumbae’ bagging. The results showed that the sugar content and enzyme activities under bagged conditions had almost the same changes as those of unbagged conditions of two cultivars during development. The sugar content in the bagged fruits was lower than those in the control fruits. At an early stage of fruit development,sugars accumulated slowly due to higher enzyme activity for sucrose cleavage than that for sucrose synthesis. At a fruit ripening stage, the sugar content increased rapidly because the enzyme activity for sucrose synthesis was higher than that for sucrose cleavage. The activity of AI had positive correlation with glucose content and SS had positive correlation with sucrose content,the activity of SPS had positive correlation with sucrose content in the control fruits of ‘ Cuiguan’.The activities of invertase at the early stage,sucrose phosphate synthase and sucrose synthase at the late stage influenced by bagging may be responsible for the decrease of sugar content in the bagging fruits.%以翠冠和黄金梨为试材,测定套袋和未套袋(对照)梨果实发育时期果实中蔗糖、葡萄糖、果糖和山梨醇含量以及蔗糖代谢相关酶酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖组分积累与酶活性的关系进行了分析.结果表明:(1)两梨品种套袋果实在发育过程中蔗糖、葡萄糖、果糖、山梨醇和糖代谢相关酶活性变化趋势与对照基本一致,套袋果实糖含量均低于对照但差异不显著,而各相关酶活性在两类果实间差异表现各异.(2)在梨果实发育早期,果实中以分解酶类为主,糖分积累低;发育后期以合成酶类为主,糖分积累多.(3)两品种套袋和对照果实AI活性与葡萄糖含量均呈显著或极显著正相关,SS合成方向活性与蔗糖含量均为极显著正相关,且翠冠对照果SPS活性与蔗糖含量呈极显著正相关.可见,套袋通过提高果实发育早期转化酶(Inv)活性,降低果实后期蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)的活性来影响糖分积累,从而影响梨果品质.
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