Klann E M, Hall B, Bennett A B
Mann Laboratory, Department of Vegetable Crops, University of California, Davis 95616, USA.
Plant Physiol. 1996 Nov;112(3):1321-30. doi: 10.1104/pp.112.3.1321.
Invertase (beta-fructosidase, EC 3.2.1.26) hydrolyzes sucrose to hexose sugars and thus plays a fundamental role in the energy requirements for plant growth and maintenance. Transgenic plants with altered extracellular acid invertase have highly disturbed growth habits. We investigated the role of intracellular soluble acid invertase in plant and fruit development. Transgenic tomato (Lycopersicon esculentum Mill.) plants expressing a constitutive antisense invertase transgene grew identically to wild-type plants. Several lines of transgenic fruit expressing a constitutive antisense invertase gene had increased sucrose and decreased hexose sugar concentrations. Each transgenic line with fruit that had increased sucrose concentrations also had greatly reduced levels of acid invertase in ripe fruit. Sucrose-accumulating fruit were approximately 30% smaller than control fruit, and this differential growth correlated with high rates of sugar accumulation during the last stage of development. These data suggest that soluble acid invertase controls sugar composition in tomato fruit and that this change in composition contributes to alterations in fruit size. In addition, sucrose-accumulating fruit have elevated rates of ethylene evolution relative to control fruit, perhaps as a result of the smaller fruit size of the sucrose-accumulating transgenic lines.
转化酶（β-果糖苷酶，EC 3.2.1.26）将蔗糖水解为己糖，因此在植物生长和维持所需能量方面发挥着重要作用。细胞外酸性转化酶发生改变的转基因植物生长习性受到严重干扰。我们研究了细胞内可溶性酸性转化酶在植物和果实发育中的作用。表达组成型反义转化酶转基因的转基因番茄（Lycopersicon esculentum Mill.）植株与野生型植株生长情况相同。几个表达组成型反义转化酶基因的转基因果实品系，其蔗糖含量增加，己糖含量降低。每个果实蔗糖浓度增加的转基因品系，成熟果实中的酸性转化酶水平也大幅降低。积累蔗糖的果实比对照果实小约30%，这种生长差异与发育后期较高的糖分积累速率相关。这些数据表明，可溶性酸性转化酶控制着番茄果实中的糖分组成，而这种组成变化导致了果实大小的改变。此外，积累蔗糖的果实相对于对照果实，乙烯释放速率升高，这可能是由于积累蔗糖的转基因品系果实较小所致。
