The clone of wheat dehydrin-like gene wzy2 and its functional analysis in Pichia pastoris

Abstract

Dehydrin is one of the responsive proteins under water-deficit stress. The aim of this study was to explore function of dehydrins in cells and the relationship with drought tolerance under water-deficit stress. We used winter wheat (Triticum aestivum) Zhengyin No.1 as the material, the complete cDNA sequence of dehydrin wzy2 was cloned and the code sequence of wzy2 was transformed into yeast (Pichia pastoris) for eukaryotic expression. We also analyzed the relationship between wheat dehydrin wzy2 gene and drought resistance. Our results indicate that the whole cDNA sequence of dehydrin wzy2 gene was 819-bp long, containing an open reading frame of 459 bp. The deduced wzy2 protein had 152 amino acid residues, which formed a 15.5 ku polypeptide with a predicted isoelectric point (pI) of 7.17. It was Y_nSK₂ type of dehydrin superfamily. Methanol was used to induce the expression of wzy2 gene in transformed P. pastoris GS115. Sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting further confirmed that the wzy2 was successfully transformed into P. pastoris and expressed specifically and effectively in yeast. With drought tolerance and cold tolerance treatment to recombinant P. pastoris, wzy2 gene can significantly improve the growth of the transgenic yeast under salt and drought stress compared with the control of pPIC9K yeast cell. However, in low temperature stress conditions, survival rate of the transferred wzy2 yeast cell had no significant improvement compared with the control of pPIC9K yeast cell. These results further indicate that Y_nSK₂ type dehydrin could be induced by salt and osmotic stress rather than low temperature.

Key words: Triticum aestivum L., eukaryotic expression, dehydrin-like, Pichia pastoris, drought tolerance.