Isolation and characterization of OsGSTL1 promoter from rice

OsGSTL1 gene was isolated from the rice genomic library. Semi-quantitative RT-PCR analysis demonstrated that the expression of the OsGSTL1 in rice was not induced by chlorsulfuron, ethylene, abscisic acid, salicylic acid, and methyl jasmonate. In order to investigate the cis-elements of OsGSTL1 promoter, the promoter regions with different lengths were fused to the beta-glucuronidase (GUS) reporter gene. All constructs were transformed into onion epidermal cells or A. thaliana plants to detect the expression patterns. In onion epidermal cells, the 160 bp fragment and longer ones were functional for directing GUS expression. In transgenic A. thaliana, the 2,155 bp upstream region of OsGSTL1 gene directed the GUS expression only in cotyledon after germination, but not in the root of young seedlings. In the later seedling, the 2,155 bp upstream region of OsGSTL1 gene directed GUS expression in roots, stems, and leaves. However, the GUS gene directed by a 1,224 bp upstream fragment is expressed in all the checked tissues. These results suggest that the spatiotemporal expression response elements of OsGSTL1 existed in the 5'-upstream region between -2,155 and -1,224 bp.