| Dehydrin (dehydrins, Dhns) belongs to the LEA-Ⅱprotein family. Its molecular weight ranges from 9 ~ 200kD. It is widespread in higher plants as the drought induced protein and plays a very important role at the growth development of seeds. When the plant tissue is under drought or salt stress, dehydrin will accumulate, as well as at the stage of seed maturation. Dehydrin is the protection responses to drought stress for plants. The structure of dehydrin maintains the stability and integrality of cell membranes and proteins.In this paper, we used wheat Zhengyin NO.1. as the materials. According to the gene sequence of dehydration we have found in our laboratory, we designed Fw1/Aw2 as the primers of wzy2 gene to clone the complete cDNA sequence of dehydrin wzy2. Wzy2 gene was subcloned into yeast Pichia pastoris for eukaryotic expression. The objective is to understand the relationship between wheat dehydrin gene and drought resistance. Our result would provide the basic information for the regulatory and transcriptional mechanism on the dehydrin gene under stress condition.We obtained the conclusions based on the above research:1. We got the whole cDNA sequence of dehydrin wzy2 gene from wheat Zhengyin NO.1. Its length was 819bp and it had an open reading frame (ORF) of 459bp, encoding 152 amino acids. It had a typical K fragment structure of dehydrin. It was YSK2 type dehydrin from a Y fragment, an S fragments and 2 K fragments.2. The dehydrin wzy2 was a neutral protein with the molecular weight of 15.5kDa. Its pI isoelectric point was 7.17; it lacked cysteine (Cys) and tryptophan (Trp). It was abundant in glycine (Gly), threonine (Thr), lysine (Lys), glutamine (Gln), histidine (His) and other hydrophilic polar amino acid; the secondary structure analysis indicated it had a transmembrane region fromα-helix by K fragment binding proteins and cell membranes. It could capture the free water in cells and maintain the structure of cells.3. We got the positive GS115 yeast Pichia pastoris containing the recombinant wzy2 DNA through the vector construction, electric conversion and selection (His+ and G418). We obtained the highly specific secretory expression of wzy2 gene with methanol induction. Wzy2 gene has been successful transformed into Pichia pastoris based on the SDS-PAGE and Western blotting identification. 4. With drought tolerance and cold tolerance treatment to recombinant Pichia pastoris, wzy2 gene can significantly improve the growth of the transgenic yeast under salt and drought stress when NaCl was higher than 0.8mol/L and sorbitol was higher than 1.6mol/L. While in the low temperature stress conditions, survival rate of the transferred wzy2 yeast cell was 37.83%±9.26% and that of pPIC9K yeast cell was 32.85%±6.33%. we found that the survival rate between two the different cells was not significant, which further demonstrate that YnSK2 type dehydrin could be induced by drought stress rather than low temperature.
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