Sugar-Modulated Expression and Developmental Control of Genes for Sucrose Metabolism

9507681 Koch形态的适应可塑性是多细胞植物最显著的特征之一。 至少有一个贡献者，这种灵活性似乎是敏感的特定植物基因糖水平（即。光催化剂可用性）。 其中包括蔗糖代谢酶的基因。 蔗糖代谢的能力强烈影响着生长器官转运蔗糖的能力，而蔗糖代谢仅由植物中两种已知的途径（转化酶和可逆的蔗糖合成酶反应）催化。 在之前的美国国家科学基金会资助下，科赫博士已经证明，玉米中编码这两种酶的基因都是碳水化合物响应性的，这提供了一种潜在的机制，可以相对于其总体可用性粗调蔗糖使用能力。 此外，新克隆的转化酶同工酶基因表现出不同的碳水化合物的反应与蔗糖合成酶同工酶基因之间观察到的惊人的相似性。 在这个项目中，科赫博士将使用分子，遗传和生理学相结合的方法来解决这些发展的意义。 探针转化酶基因家族（pupestrile可溶性）提供了一个机会，以解决糖响应基因的表达和可溶性转化酶的广泛作用，在最初的增长新扩大的水槽组织之间的关系。

9507681 Koch Adaptive plasticity of form is one of the most remarkable features of multicelled plants. At least one contributor to this flexibility appears to be the sensitivity of specific plant genes to sugar levels (ie. photosynthate availability). Among these are the genes for sucrose metabolizing enzymes. Import of translocated sucrose by growing organs can be strongly affected by the capacity for sucrose metabolism, which is catalyzed by only two known pathways in plant (invertase and the reversible sucrose synthase reaction). Under previous NSF grant, Dr. Koch has demonstrated that genes encoding both these enzymes in maize are carbohydrate-responsive, providing a potential mechanism for coarse adjustment of capacity for sucrose use relative to its overall availability. In addition, the newly cloned isozyme genes for invertase exhibit a differential carbohydrate responsiveness with surprising similarity to that observed among isozyme genes of sucrose synthase. In this project, Dr. Koch will address the significance of these developments using a combined molecular, genetic and physiological approach. Probes for an invertase gene family (putatively soluble) provide an opportunity to address the relationship between sugar-responsive gene expression and the widespread role of soluble invertases in initial growth by newly expanding sink tissues.