温州蜜柑果实发育期间果糖激酶与糖积累的关系

研究了温州蜜柑果实发育进程中糖含量变化与果糖激酶活性变化的关系及增施氮肥对果实果糖激酶活性和基因表达的影响.结果表明,随着果实的发育,可食组织果糖激酶活性逐渐降低,糖含量不断增加,果皮中蔗糖和葡萄糖含量在成熟期略有下降,果糖激酶活性略有升高.果实膨大期后增施氮肥的果实在成熟期可食组织及果皮中蔗糖和果糖所占比例均有所下降,葡萄糖比例升高,以单位蛋白质表示的果糖激酶活性也明显高于对照果实.Northern分析表明,增施氮肥能促进发育后期果实可食组织中Cufrkl基因的表达,但对Cufrk2的表达无明显作用.

The Relationship of Fructokinase and Sugar Accumulation During Fruit Development in Satsuma Mandarin

Sugars accumulation and fructokinase ac- tivity during satsuma mandarin fruit development in relation to the effect of extra nitrogenous fertilizer on the activity and expression of fructokinase were studied. The results exhibited that fructokinase activ- ity in the tissues of edible and peel decreased during fruit development, which coincided with the accumu- lation of sugars (Figs.1 and 2), while the contents of sucrose and glucose decreased, and the activity of the enzyme increased in peel tissues of ripened fruit. Af- ter fertilizing with extra urea, the ratios of sucrose and fructose decreased in ripe fruit, while that of glucose increased compared to the control (Fig.3). The activ- ity of fructokinase presented on a protein basis in- creased in treated fruit (Fig.4). Northern analysis con- firmed that extra nitrogenous fertilizer enhanced the expression of Cufrk1 at the late stage of fruit development, but had no effect on Cufrk2 (Fig.5). The results suggest that the two different genes of citrus FRK may play distinct roles in sink metabolism and Cufrk1-encoded fructokinase protein could be induced by fertilization with extra nitrogen.