Abstract: Two cDNA fragments of fad2 gene were cloned using degenerate primers from Caragana intermedia which is an important bio-erergy plant.The DNA sequence analysis indicated that the fragments contain 452 and 480 bp, and share 88 % of homology with Glycine max Gm fad2-2a in Genbank.Both of the gene fragments were registered in Genbank (AY957393, AY957394).The fragment AY957394(452 bp) was digested with the enzyme BamHI and SacI, and ligated to the corresponding sites of the pBI121 in the antisense orientation.The pBI121 fad2 vector was introduced into Agrobacterium tumefaciens strain LB4404 by electroporation and transformed to leaf of tobacco via A.tumefaciens system.Plantlets were regenerated in vitro by resistance selection on medium containing Ampicillin and Knamycin.PCR amplification results with primer designed according to the fad2 gene fragment and NPT II gene in pBI121 demonstrated that antisense fad2 was integrated into tobacco genomes.The preliminary analysis showed that compared with the untransgenic tobacco plants, the fatty acid content of transgenic tobacco seeds was at the same level, but the lenoleic acid content was 10.3 % less.More research is still doing on the transgenic tobacco plants T1 to know more about fad2 function.The results generated in this experiment will be used to study how to improve the fatty acid composition in oil plants with gene technique according to the biodiesel production.

Key words: Caragana intermedia, fad2 gene, antisense expression vector