Several cis-elements including a palindrome involved in pollen-specific activity of SBgLR promoter.
SBgLR (Solanum tuberosum genomic lysine-rich) is a pollen-specific gene cloned from potato (Solanum tuberosum L.). The region from -269 to -9 (The A of translation start site "ATG" as +1) of the SBgLR promoter was identified as critical for gene specific expression in pollen grains. Sequence analysis indicates a palindromic sequence "TTTCTATTATAATAGAAA" in the -227 to -209 region, in which two pollen-specific motifs TTTCT and AGAAA surround a unique putative TATA box. Moreover, nine putative pollen-specific motifs are located in the region between the TATA box and ATG. We placed the -227 to -9 region (reserving the palindrome) and the -222 to -9 region (breaking the palindrome) downstream of the CaMV35S enhancer, respectively, to construct two fusion promoters. Histochemical assays in transgenic plants demonstrated that the region from -222 to -9 is necessary and sufficient for pollen-specific expression of the uidA gene. However, the region of -227 to -9 is incapable of driving GUS expression in pollen grains and parts of vegetative tissues. A series of 5' deletions from -269 to -9 of SBgLR promoter were constructed. A transient expression assay indicated that the region from the -227 to -9 suppressed gfp gene expression in pollen, and a positive regulatory element was present in the region of -253 to -227. The function of the palindromic sequence as a repressor inhibiting gene expression in pollen was further confirmed by the mutated promoter, breaking the palindrome by substituting its 3'-flanking five base pairs, which resumes the reporter gene expression in mature pollen.
Zhou
Peng
P
State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China.
Yang
Fang
F
Yu
Jingjuan
J
Ao
Guangming
G
Zhao
Qian
Q
D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D055029:Inverted Repeat Sequences; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000235:genetics; D011058:Pollen / Q000235:genetics*; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D011198:Solanum tuberosum / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics; D014170:Transformation, Genetic