砧木对小型早熟西瓜果实糖代谢及相关酶活性的影响

 以小型西瓜品种‘小兰’自根植株为对照, 研究‘杭州长瓠’、‘超丰F₁’、‘勇士’、‘黑籽南瓜’4 种砧木对其果实糖代谢特性及相关酶活性的影响。结果表明: 4 种嫁接西瓜果实发育过程中蔗糖、葡萄糖、果糖含量和糖代谢酶活性变化趋势与自根西瓜一致。在果实发育早期, 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。西瓜嫁接后果实糖分含量明显降低, 降低程度依砧木而异, 超丰F₁/ 小兰、杭州长瓠/ 小兰西瓜的糖含量明显高于黑籽南瓜/ 小兰、勇士/ 小兰。砧木可能主要通过影响果实发育早期转化酶( Inv) 、发育后期蔗糖磷酸合酶(SPS) 、蔗糖合酶(SS) 活性来影响糖分积累。各处理糖代谢酶的净活性与糖分积累存在较好相关性, 说明糖代谢酶在西瓜果实糖分积累中的作用是综合的, 造成自根及嫁接西瓜果实糖分积累的差异是Inv、SPS、SS 几种酶共同作用的结果。

The Effects of Different Rootstocks on the Sugar Metabolism and Related Enzyme Activities in Small and Early-maturing Watermelon during Fruit Development

The sugar metabolism and their related enzyme activities during fruit development of own-rooted and grafted on Hangzhou-long gourd,Chaofeng F 1, Yongshi and Figleaf gourd watermelon were studied.The results showed that the changes of sugar content and sucrose metabolism enzyme activity during the fruit development of different grafted and own-rooted watermelon were similar.At an early stage of fruit development,sugars accumulated slowly due to higher enzyme activity for sucrose cleavage than for sucrose synthesis.At a fruit ripening stage,the sugar content increased rapidly because the enzyme activity for sucrose synthesis was higher than for sucrose cleavage.However,the sugar content in the fruits of all grafted watermelons were lower than that in the fruit of own-rooted watermelon.Among the grafted watermelon fruits,the sugar content of the watermelon grafted on Chaofeng F 1 and Hangzhou-long gourd was higher than that of watermelon grafted on Figleaf gourd and Yongshi.The activities of invertase at the early stage,sucrose phosphate synthase and sucrose synthase at the late stage influenced by grafting may be responsible for the decrease of sugar content in the grafted watermelon fruit.The good relationship between sugar accumulation and net enzyme activity of sucrose metabolism indicated that sucrose metabolism enzymes including invertase,sucrose phosphate synthase and sucrose synthase may function together,which resulted in the difference of sugar content in own-rooted and grafted watermelon fruits.