Molecular cloning and characterization of a novel microsomal oleate desaturase gene DiFAD2 from Davidia involucrata Baill

In the conversion of oleic acid to linoleic acid, delta(12)-fatty acid desaturase (delta(12)-FAD) is involved. Based on the conserved oligo amino acid residues of the FAD2 genes from other plants, a new full-length cDNA (DiFAD2) encoding a delta(12)-FAD was cloned from Davidia involucrata Baill. Sequence analysis indicated that the DiFAD2 gene had an open reading frame (ORF) of 1 149 bp, coding for 382 amino acids residues of 44.3 kDa, pI of the deduced protein was 8.8. The deduced amino acid sequence of the cloned DiFAD2 showed high identities to those genes of other plant delta(12)-FAD. RT-PCR showed that DiFAD2 was expressed in all tissues and expression was abundant in young stems. Expression of DiFAD2 is not enhanced by low temperature and the altered polyunsaturated fatty acid content in leaves treated with low temperature may be due to the post-transcriptional regulation of the DiFAD2 gene or the other FAD2 gene family regulation