Two cis-acting regulatory elements are involved in the sucrose-inducible expression of the sporamin gene promoter from sweet potato in transgenic tobacco.
In this study, we generated transgenic tobacco plants that express the beta-glucuronidase (GUS) gene under the control of the 305-bp 5'-upstream region of a gene coding for sporamin A of sweet potato. Expression of GUS in excised tobacco leaves was induced by sucrose, mimicking the sugar-inducible expression of the endogenous sporamin genes in sweet potato. Deletion of the sequences extending from position -305 (relative to the transcription start site) to -283 and from -146 to -87 resulted in an approximately 40-fold enhancement in GUS reporter expression. Furthermore, the sequence from -282 to -165 conferred sucrose-inducibility on the -89 core promoter of the Cauliflower Mosaic Virus 35S RNA gene. Analysis of internal deletions, linker scanning and the introduction of base substitutions in the sequence between positions -282 and -165 indicated that sucrose-responsiveness conferred by this region was dependent on the presence of two cis-acting elements, termed CMSREs (carbohydrate metabolite signal responsive elements) 1 and 2, which are separated by a spacer. A sequence similar or identical to the core of CMSRE-1 (TGGACGG) is also present in the promoters of several other sugar-inducible genes, and sequences encopassing the TGGACGG-related motifs from two of these could functionally replace the CMSRE-1 in the truncated sporamin A promoter. These results suggest that the TGGACGG element plays an important role in the sucrose-inducible expression of a group of plant genes.
Morikami
Atsushi
A
Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan. morikami@ccmfs.meijo-u.ac.jp
Matsunaga
Rie
R
Tanaka
Yoshimi
Y
Suzuki
Satomi
S
Mano
Shoji
S
Nakamura
Kenzo
K
D001483:Base Sequence; D017796:Caulimovirus / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D017384:Sequence Deletion; D013395:Sucrose / Q000494:pharmacology*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism
D010940:Plant Proteins; C053374:sporamin A protein, Ipomoea batatas; D013395:Sucrose; D005966:Glucuronidase