Cloning of dehydrin coding sequences from Brassica juncea and Brassica napus and their low temperature-inducible expression in germinating seeds

A novel subclass of dehydrin genes, homologous to the Raphanus sativus late embryogenesis-abundant (LEA) protein (RsLEA2) and the Arabidopsis thaliana dehydrin, was isolated from Brassica juncea and Brassica napus, here designated BjDHN1 and BnDHN1, respectively. The cDNA of BjDHN1 and BnDHN1 genes share 100% nucleotide identity. The encoded protein is predicted to consist of 183 amino acid residues (molecular mass of 19.2 kDa and pI of 7.0). It shares 85.3% and 65.4% amino acid sequence identity with the RsLEA2 and Arabidopsis dehydrin, respectively. This Brassica dehydrin also features a “Y3SK2” plant dehydrin structure. Expression analysis indicated that the Brassica dehydrin gene is expressed at the late stages of developing siliques, suggesting that the gene expression may be inducible by water-deficit. Analysis of gene expression also indicated that in germinating seeds the gene expression was inducible by low temperature. Seed germination under low temperature was compared between B. juncea and B. napus. The results showed that B. juncea seeds germinated faster than B. napus seeds. Expression of Brassica dehydrin gene was also examined as a function of seed germination under low temperature.