| Drought is one of major abiotic stress which can greatly reduce the production ofmaize. The protein disulfide isomerase(PDI)is an abundant oxidoreductase enzyme in theendoplasmic reticulum(ER). This enzyme catalyzes disulfide formation and isomerization,and behaves as a chaperone inhabiting the aggregation ofmisfolded proteins. It may haveeffect on drought tolerance. We hope to find the key gene about drought tolerance throughthis experiment, and then can supply gene in support of maize breeding and gene transfertechnology.The PDI gene was isolated from suppression subtractive hybridizationlibrary(constructed by Maize Research Department, Institute of Crop Science, ChineseAcademy of Agricultural Sciences)of maize in flower time, which was induced by waterstress. We cloned it by RT-PCR from silks of maize. The GenBank accession is EF532321.The analysis of Bioinformatics indicated that the opening reading-frame(ORF)of this geneis 1542 bp and encoding 513 amino acid. The molecular formula of the protein isC2577H3980N6480771S11, the molecular weight is 56.7 KDa and the isoelectricpoint(PI)is 5.01. Phylogenic analysis displayed that PDI of species in maize had a closerelationship with those of rice. Through northern blot, we can see the PDI gene wasinduced by water stress, salt stress, ABA stress and cold stress. Through subcelluarlocalization, we can see the PDI gene was expressed in nucleus, cytoplasm, membrane,and most of it expressed in cytoplasm. However, it need to be proved by more accuratelocation analysis whether this gene expressed in ER.To identify the function of PDI, weconstructed the over-expression vector of this gene, and then transferred it into Arabidopsisthaliana via floral dipping. We find that germination of transgenic Arabidopsis seeds isbetter than wild-type Arabidopsis seeds in salt stress and mannitol stress. In conclusion, PDI is induced by abiotic stress, and its over-expression contributed toabiotic stress tolerance in transgenic Arabidopsis thaliana.
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