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

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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.