Strabala T J, Crowell D N, Amasino R M
Department of Biochemistry, University of Wisconsin-Madison 53706.
Plant Mol Biol. 1993 Mar;21(6):1011-21. doi: 10.1007/BF00023599.
The location of gene expression of the Agrobacterium tumefaciens ipt gene promoter in transgenic tobacco plants was examined using the beta-glucuronidase (GUS) reporter gene. Expression of GUS was detected in every organ and most cell types examined. The highest levels of GUS activity were found in roots. To further examine the transcriptional basis of this broad expression pattern, deletions in the 5' non-coding region of the gene were translationally fused to two promoterless reporter genes, encoding the enzymes chloramphenicol acetyl transferase (CAT) and beta-glucuronidase (GUS). Reporter enzyme assays revealed the existence of an upstream segment required for maximal promoter function, the 5' end of which is between -442 and -408 of the Pipt ATG codon. This upstream segment is required for maximal levels of GUS expression in roots, but not in other organs, and a tobacco suspension-cultured cell line. The implications of broad ipt expression on the process of crown gall tumorigenesis are discussed.
利用β-葡萄糖醛酸酶（GUS）报告基因检测了根癌农杆菌ipt基因启动子在转基因烟草植株中的基因表达位置。在所检测的每个器官和大多数细胞类型中均检测到了GUS的表达。GUS活性最高的部位是根。为了进一步研究这种广泛表达模式的转录基础，将该基因5′非编码区的缺失片段与两个无启动子报告基因进行翻译融合，这两个报告基因分别编码氯霉素乙酰转移酶（CAT）和β-葡萄糖醛酸酶（GUS）。报告酶分析揭示了最大启动子功能所需的上游片段的存在，其5′端位于Pipt ATG密码子的-442至-408之间。该上游片段是根中GUS最大表达水平所必需的，但在其他器官和烟草悬浮培养细胞系中并非如此。文中讨论了ipt广泛表达对冠瘿瘤发生过程的影响。
