Abstract: The lotus（Nelumbo nucifera Gaertn）seed defensin gene was identified from the lotus cDNA library of middle development stage seed embryo. The 561 bp full length cDNA have a 234 bp open reading frame which encoding a 77 amino acid peptide and was designated as NnDefensin. The amino acid sequence of NnDefensin showed relatively high match with other plant defensin genes and phylogeny analysis showed that NnDefensin have close relationship with defensin from Oryza sativa japonica group，defensin precursor from Triticum aestivum and defensin from Plantago major. NnDefensin have a strictly conserved γ- thionin domain of eight cysteine which is characteristic in plant defencin. Specific primers containing restriction enzyme site of SmaⅠ and SacⅠ was used to amplify the sequence of NnDefensin by polymerase chain reaction（PCR）. The binary expression vector pBI121 and vector pAhOleo17.8︰GUS which containing a seed specific promoter were digested by the corresponding restricted enzymes respectively，and linked with the NnDefinsin fragment directionally. The resulting construction was obtained and named pBI121-NnDef in which NnDefensin was driven by 35S promoter，and pAhOleo-NnDef in which NnDefensin was driven by seed specific promoter AhOleo17.8 from peanut（Arachis hypogaea L.）. The vectors could be transformed into plants mediated by Agrobacterium tumefaciens for the following up research such as gene functional identification and gene transformation for pathogen resistant improvement in transgenic plants and seeds.

Key words: Nelumbo nucifera Gaertn, defensin, vector construction, seed specific