Abstract：Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in glycolysis, but the role of GAPC (cytosolic glyceraldehyde-3-phosphate dehydrogenase), which is a cytosolic GAPDH isoform and catalyzes the conversion of 3-phosphoglyceraldehyde to 1,3-diphosphoglyceric acid, against abiotic stresses is largely unknown. In this study, the TaGAPC1 gene encoding 337 amino acids and the TaGAPC1 promoter named P973 were both cloned. We fused the TaGAPC1 to green fluorescent protein gene (GFP) and transformed it into onion (Allium cepa) epidermal cells, the result showed that TaGAPC1 protein localized on the cytomembrane. Quantitative real-time PCR was used to detect TaGAPC1 expression in leaf, root and stem or under PEG8000, NaCl, ABA, and 4 ℃ stresses, the results indicated that the expression levels of TaGAPC1 gene in leaf, root, and stem gradually declined, and TaGAPC1 expression was induced by PEG8000, NaCl, and ABA treatments, but it did not response to 4 ℃ treatment. The PLACE (http://www.dna.affrc.go.jp/PLACE/) and PlantCARE (http://bioinformatics.psb.ugent.be/webtools/plantcare/html/) database indicated that some cis-acting elements responsive to abiotic stress were present in P973 promoter, such as Drought-responsive element (DRE), ABA-responsive element (ABRE), MYB-binding site (MBS) and WUN-motif. Based on the position of cis-acting elements in TaGAPC1 promoter, 5 deletions named P844, P738, P605, P475, and P256 were respectively amplified. After the 6 promoters were fused to β-glucuronidase gene (GUS) and transformation into tabacco (Nicotiana batacum) was performed, GUS activity driven by the 6 promoters under PEG8000, NaCl, ABA, and 4 ℃ stresses were determined. The result suggested that TaGAPC1 promoter region from -973 to -605 was essential for the response to PEG8000 and NaCl, the region from -973 to -475 was essential for the response to ABA. The study illustrated the relationship of TaGAPC1 gene with abiotic stress response at molecular level, and lay foundation for further exploring TaGAPC1's molecular mechanism under stress.
