Effect of activity of the cell wall and vacuole invertase on the sugar accumulation in the strawberry fruit

为了阐明草莓果实糖分积累的机理，研究了草莓果实糖分含量与蔗糖酶活性的关系，并对转化酶基因进行了分离和分析。并对叶片培养再生不定芽的情况进行了研究。虽然‘灵光’的葡萄糖和果糖含量不随果实成熟而增加，但蔗糖含量在果实成熟后期有所增加。在‘丰冈’中，葡萄糖和果糖的含量从早期就增加了，这些糖在以后继续增加。葡萄糖和果糖积累的‘丰冈’品种与蔗糖积累的‘灵子’品种的细胞壁转化酶活性没有差异。而蔗糖积累‘灵子’的活性变化不大，而葡萄糖和果糖积累的‘丰冈’活性增加，趋势与还原糖的变化趋势相似。在进行转化酶基因克隆时，分离到两种基因片段(inv1和inv2)。从均相参考的结果来看，inv1是液泡型转化酶基因的一部分(520bp)，inv2是转化酶基因的细胞壁型的一部分(471bp)。以Inv1为基础制备的抗体进行Western blotting，结果表明，积累了葡萄糖和果糖的‘丰冈’品种的液泡转化酶主要出现在果实成熟期的早期。1作为控制草莓糖积累的因素，液泡型转化酶的活性似乎受到了极大的关注。在1/2MS附加2.4D、CPPU或TDZ的1/2MS培养基上，在黑暗和25℃的条件下，‘Nyohou’和‘Reiko’的出芽率达到60%以上，而‘丰冈’的出苗率只有5%。

In order to clarify the accumulation mechanism of the sugar in strawberry fruits, the relation between the sugar content in the fruit and inyertase activity was investigated, and isolation and analysis of the invertase gene were carried out. Also the regeneration of shoot from the leaf culture was examined.1. Though glucose and fructose content of 'Reiko' did not increase with the maturation of the fruit, the sucrose content increased at the later stage in the fruit maturation. In 'Toyonoka', glucose and fructose content increased from the early stage, and these sugars continue to increase afterwards.2. The cell wall invertase activity did not differ between the glucose and fructose accumulated 'Toyonoka' variety **d the sucrose accumulated 'Reiko' variety. Whereas the change in the activity of the sucrose accumulated 'Reiko' variety was small, though the activity of the glucose and' fructose accumulated 'Toyonoka' variety, increased, and the tendency was similar to the change of the reducing sugar.3. When the cloning of an invertase gene was performed, two kinds of gene fragments (inv 1 and inv 2) were isolated. From the result of the homogeneous reference, inv 1 was a part of vacuole type invertase mRNA (520bp), and inv 2 was a part of cell wall type in Invertase mRNA (471bp). From the result of western blotting using the antibody made on the basis of inv 1, it was shown that vacuole invertase of the glucose and fructose accumulated 'Toyonoka' variety had mainly appeared at early stage in the fruit maturation.1 As controlling factor the sugar accumulation of the strawberry, the activity of the vacuole type invertase seemed to be greatly concerned.4. When the piece of a leaf was put on 1/2MS medium, which added 2.4D, CPPU, or TDZ and was kept under the dark and 25℃ condition, the rate of the shot formation in 'Nyohou' and 'Reiko' became 60% or more, but the rate of that in ' Toyonoka' was only 5% on this condition.