糖代谢相关酶和GA_3、ABA在嫁接伽师瓜果实糖分积累中的作用

在不同发育时期测定了嫁接伽师瓜果实中蔗糖、葡萄糖和果糖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,并对果实中糖积累与酶活性和激素含量的关系进行了分析。结果表明:蔗糖代谢相关酶和激素的综合作用是影响果实糖积累的重要因子之一;嫁接伽师瓜间果实发育过程中蔗糖、葡萄糖、果糖和糖代谢酶活性变化趋势基本一致。在果实发育早期,果实中以分解酶为主,糖分积累少;发育后期以合成酶为主,糖分积累多。嫁接伽师瓜果实糖分含量与同期自根伽师瓜相比明显减少;但嫁接伽师瓜植株生育期比自根伽师瓜延迟20-28d,果实生育期延迟15-18d,此时嫁接伽师瓜果实糖分含量明显高于自根伽师瓜。嫁接伽师瓜果实中ABA和GA3含量的变化明显滞后于自根伽师瓜,砧木可能通过影响果实糖代谢相关酶活性和激素含量来影响果实中糖分积累。

Roles of sugar-metabolizing enzymes and GA3, ABA in sugars accumulation in grafted muskmelon fruit

The content of sucrose, glucose, fructose and the activities of sucrose-metabolizing enzymes (acid invertase, neutral invertase, sucrose synthase and sucrose phosphate synthase) were studied during fruit developing of 'Jiashi' muskmelon (Cucumis melo var. saccharinus Naud) grafted on armour, black seed pumpkin and gourd. The results indicated that the composite action of sucrose-metabolizing enzymes was one of the important factors affecting sugar accumulation in fruit. The transition of sugar accumulation and activity of sucrose-metabolizing enzymes during fruit development of grafted and non-grafted muskmelon were similar. At an early stage of fruit development, sugar accumulated slowly due to higher enzyme activity for sucrose cleavage than that for sucrose synthesis. At a late stage of fruit development, the sugar content increased rapidly because the enzyme activity of sucrose synthesis was higher than that of sucrose cleavage. However, the sugar content in the fruit of all grafted muskmelon were lower than that in the fruit of non-grafted muskmelon during the same stage. However, the development duration of the grafted muskmelon was (20-28 d) longer than that of non-grafted. The fruit maturity date of the grafted muskmelon was delayed for 15-18 d than that of non-grafted. The sugar content in the ripe fruit of grafted muskmelon was higher than that in the fruit of non-grafted muskmelon. The changes of abscisic acid (ABA) and GA3 in the fruit of all grafted muskmelon were retarded and their contents were more than those in non-grafted muskmelon. The activities of invertase at early stage, sucrose phosphate synthase, sucrose synthase and abscisic acid at the late stage influenced by grafting may be responsible for the difference in the accumulation of sugar content in the grafted muskmelon fruit.