Physiological Role of Sugar-Modulated Gene Expression in Higher Plants

糖调节基因表达在高等植物中的生理作用

• 批准号: 8816776
• 负责人: Karen Koch
• 金额: $ 22.36万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-06-01 至 1993-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8816776&HistoricalAwards=false
• 关键词: Physiological; Role; Sugar; Modulated; Gene

Central to plant biology are the processes which govern allocation of photosynthetic products among growing tissues. Recent findings indicate that distribution and metabolism of these resources may be regulated in part by short-term alterations of gene expression in response to carbohydrate availability. Sucrose synthase is the primary enzyme responsible for sucrose hydrolysis in many developing plant tissues which depend on imported sucrose. This laboratory has shown that expression of a gene encoding this enzyme in maize root tips is modulated by the level of sugars present. This research goals are to: 1) characterize the role of carbohydrate status in regulation of sucrose synthase (Sh1) gene expression, 2) define the physiological consequences of rapid changes in Sh1 expression, and 3) identify other carbohydrate regulated genes. The approach will combine metabolic studies with quantification of gene expression using gene specific DNA probes and antibodies. The conditions under which this response occurs in vivo will be established. In addition, maize sucrose synthase and invertase mutants will be used to assess the metabolic effects of short- term changes in sucrose synthase gene expression. Finally, the possiblity that this response includes other metabolically important genes in addition to sucrose synthase will be addressed. This research will contribute not only to the clarification of the interplay between gene expression and metabolism, but also to elucidation of mechanisms controlling sucrose allocation in higher plants. Perhaps the first example of sugar-modulated expression of an identified plant gene has been described by this laboratory. Specifically, the Sh1 form of sucrose synthase is rapidly and selectively induced in maize root tips depleted of sucrose. Sucrose is the predominant form in which sugars are redistributed in most species, therefore its synthesis and breakdown are crucial to the plant. Sucrose synthase catalyzes a reversible cleavage of sucrose, and is thus vital in tissues which import and metabolize sucrose. In many instances, sucrose synthase activity is positively correlated with the extent of sucrose movement into a given tissue. Therefore, the interaction of sugar levels with sucrose synthase gene expression is a potential mechanism for regulation of sucrose import and utilization. This research explores sugar regulation of sucrose synthase expression and its metabolic consequences, in detail, at the molecular, cellular, and whole plant levels.

植物生物学的核心是控制生长组织间光合产物分配的过程。最近的研究结果表明，这些资源的分布和代谢可能在一定程度上受短期基因表达变化的调节，以响应碳水化合物的可用性。蔗糖合酶是许多依赖进口蔗糖的发育中的植物组织中负责蔗糖水解的主要酶。这个实验室已经证明，编码这种酶的基因在玉米根尖上的表达是由存在的糖水平调节的。本研究的目标是：1)表征糖的状态对蔗糖合酶（Sh1）基因表达的调控作用，2)确定Sh1表达快速变化的生理后果，3)鉴定其他糖的调控基因。该方法将代谢研究与基因特异性DNA探针和抗体的基因表达定量结合起来。将建立这种反应在体内发生的条件。此外，玉米蔗糖合酶和转化酶突变体将被用来评估短期内蔗糖合酶基因表达变化对代谢的影响。最后，除了蔗糖合酶外，这种反应还包括其他代谢重要基因的可能性将得到解决。本研究不仅有助于阐明基因表达与代谢之间的相互作用，而且有助于阐明高等植物蔗糖分配的调控机制。也许这个实验室已经描述了糖调节植物基因表达的第一个例子。具体来说，蔗糖合酶的Sh1形式在蔗糖匮乏的玉米根尖上被快速和选择性地诱导。蔗糖是大多数物种中糖重新分配的主要形式，因此它的合成和分解对植物至关重要。蔗糖合酶催化蔗糖的可逆裂解，因此在组织中进口和代谢蔗糖是至关重要的。在许多情况下，蔗糖合酶活性与蔗糖进入特定组织的程度呈正相关。因此，糖水平与蔗糖合酶基因表达的相互作用是调控蔗糖进口和利用的潜在机制。本研究在分子、细胞和整个植物水平上详细探讨了糖对蔗糖合酶表达的调节及其代谢后果。