Molecular genetic analysis of sugar-inducible gene expression in plant.

植物养分的储存和分配规则，如碳和氮，与作物的生产力相关。这个系统中的许多基因都受供应给植物组织的糖浓度的调节。在本研究中，我们建立了一种新的拟南芥突变体筛选体系，以分析参与这一调控的因素。甘薯块根中主要存在的一种贮藏蛋白--孢子胺的基因表达受高浓度糖供应的诱导。我们利用转基因烟草对该基因的启动子区域进行了分析，发现两个顺式调控元件对该基因的调控是必需的。AG221-启动子是一个去除了原来的孢子胺启动子的不必要区域的启动子，与原来的启动子相比，它对糖水平的影响非常明显。我们构建了AG221启动子与LUC编码区融合的转录荧光素酶(Lug)融合基因，并将其导入拟南芥基因组中。该融合基因在高浓度蔗糖和果糖处理后24小时内被激活，且呈浓度依赖关系。将含有该融合基因的转基因品系导入EMS进行诱变，从后代中筛选出突变体。在0%和6%蔗糖处理下，获得了29个LUC活性较强的突变体，19个没有LUC活性的突变体，25个在高浓度蔗糖处理下活性很低的突变体。

Regulations of storage and partitioning of plant nutrients like as carbon and nitrogen are correlated with the productivity of crops. Many genes in this system are regulated with the concentration of sugars supplied to plant tissues. In this study, we established a new system for screening of mutant of Arabidopsis thaliana to analyze the factors involving this regulation.The expression revel of the gene for a storage protein, sporamin that exists predominantly in tuberous root of sweet potato is induced by the supply of high concentration of sugars. Our analysis of promoter region of this gene by using transgenic tobacco revealed that two cis-regulatory elements are necessary to this regulation.AG221-promoter is a promoter which removed unnecessary region of original sporamin promoter and whose responsibility to sugar-level is highly apparent, compared with original promoter. We constructed a transcriptional Luciferase (LUG) fusion gene in which AG221 promoter was fused with LUC coding region and introduced this fusion gene into the genome of Arabidopsis thaliana. This fusion gene was activated in 24h after treatment of high concentration of matabolitable sugar like as sucrose and fructose with a concentration dependent manner.A transgenic line containing the fusion gene was introduced mutations with EMS and mutants were screened from the descendants. We got 29 lines of mutants which have strong LUC activity with the treatment with 0% and 6% sucrose, 19 lines of mutants which have no LUC activity and 25 lines of mutants which have very low activity when tissue was treated with high concentration of sugars.