Molecular cloning and expression of glyceraldehyde-3-phosphate dehydrogenase gene under environmental stresses in sweetpotato

Abstract

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a main enzyme in the glycolytic pathway, is involved in cellular energy production and regarded as a housekeeping gene. Previously, cytosolic GAPDH was selected as the most significantly abundant gene in EST library of sweetpotato suspension cells. In this study, a full-length of cDNA clone (IbGAPDH) encoding GAPDH was isolated from suspension-cultured cells of sweetpotato (Ipomoea babatas), and its expression was investigated with a view to understanding the physiological function of GAPDH in relation to environmental stresses. IbGAPDH encoded a 36.9 kDa polypeptide consisting of 337 amino acids. When the deduced amino acid of IbGAPDH was compared with other higher plants, IbGAPDH showed high homology with cytosolic GAPDH. The mRNA level of IbGAPDH significantly increased under environmental stresses, such as <TEX>$H_2O_2$</TEX>, MV and cold treatments. Among them, the transcript level of IbGAPDH gene was the highest under cold stress. Further investigation of the transcription level under <TEX>$10^{\circ}C$</TEX> or <TEX>$15^{\circ}C$</TEX> was performed with different tissues of sweetpotato. The transcription of IbGAPDH was increased by cold stress with tissue-specificity, moreover, showed different patterns according to temperature.