Abstract:

Based on a constructed EST library of Camellia oleifera,a fulllength cDNA encoding a dehydrin was cloned from its seed by the electronic PCR technique. The cDNA, tentatively designated as CoDHN1, was 1 406 bp long containing an open reading frame of 600 bp. The deduced CoDHN1 protein had 200 amino acid residues, which formed a 21 ku polypeptide with a predicted isoelectric point (pI) of 7 The CoDHN1 protein had two Y segments, an Ssegment and two Ksegments. Homology analysis indicated that the Ysegment, Ssegment and Ksegment of CoDHN1 shared identity with those of other reported dehydrins, indicating that CoDHN belonged to dehydrin superfamily. There was a wide range of variation for Thrregion existed among dehydrins from various species, and the CoDHN1 Thr region was Camellia oleifera specific, protecting some macromolecules by forming hydrated layer outside of them. A very conserved motif of EDDGQGGRRKK was found in CoDHN1, and it might contribute to dehydrin's phosphorylation and subcellular localization. By comparison with dehydrins from citrus and Arabidopsis respectively, it was proposed that CoDHN1 might serve as a buffer for transiently increased Ca 2+ when the matured seeds was under the condition of desiccation stress to some extent, and that CoDHN1 might bind heavy metal ions such as Cu 2,Ni 2＋,Zn 2＋,Co2＋,Fe3＋and hence scavenge reactive oxygen species to alleviate toxin caused by them.

Key words: Camellia oleifera, dehydrin, cDNA library, RACE, physiological role, bioinformatics