Abstract:

【Objective】 This study was designed to discover the LEA (low erucic acid) wild species, and to reveal the genetic mechanism of the LEA trait. 【Method】 Homologous sequence amplification strategy was used in gene isolation. Heterologous expression of the FAE1 genes was made using the yeast system, and the fatty acid composition was analyzed by gas chromatography. 【Result】 The multiple sequence alignment showed that FAE1 genes shared over 85% identities between the wild species and the rapeseed variety. The amino acid residues (Ser282, Cys223, His302, His387, His391, and His420), reportedly active sites for β-ketoacyl-CoA synthase, were conserved as those in high erucic acid rapeseed. Western blot analysis showed that the FAE1 genes from all of the wild crucifer species were expressed in yeast, whereas the yeast cells expressing FAE1 genes from Orychophragmus violaceus and Capsella buraspastroil showed no formation of very long chain fatty acid (VLCFA). Meanwhile, those expressing FAE1 genes from Sinapis arvensis, Sinapis alba, and Isatis indigotica produced small quantity of VLCFA which was absent in control yeast cells. 【Conclusion】 The experiment indicated that O. violaceus and C. buraspastroil are LEA wild species in which loss of activity of the protein encoded by the FAE1 gene might be responsible for the LEA trait.

Key words: crucifer species, fatty acid elongase 1, sequence alignment, yeast expression, low erucic acid wild species