Molecular Cloning and Expression Analysis of an Oleate Desaturase Gene DsFAD6 from Descurainia sophia

DsFAD6 encoding a plastidial oleate desaturase, a key enzyme for catalyzing oleic into linoleic acid, was isolated from Descurainia sophia using RACE-PCR approach. The full-length cDNA of DsFAD6 with a complete open reading frame of 1344bp, encoded a peptide of 447 amino acid residues with a predicted molecular mass of 51.16kD and a PT of 9.27. Sequence analysis showed the three histidine boxes characteristic of all membrane-bound desaturases and a N-terminal plastidial signal peptide. Sequence alignment and phylogenetic tree analysis showed that DsFAD6 was more like FAD6s from cruciferous species. Expression analysis by RT-PCR showed that DsFAD6 gene was expressed in all tissues detected, but higher in stems, leaves and young siliques. In addition, the expression of DsFAD6 gene was induced by wounding, but inhibited by cold stress in leaves.