Identification and Characterization of a Plastidial ω3-fatty Acid Desaturase Gene from Jatropha curcas

Based on the sequence information of the ω3-fatty acid desaturase genes from Arabidopsis thaliana, Nicotiana tabacum, Betula pendula and Ricinus communis, a cDNA putatively encoding a plastidial ω3-fatty acid desaturase (JcFAD7) was isolated from Jatroha curcas with reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that this cDNA sequence had an open reading frame (ORF) of 1 368 bp encoding 455 amino acids of 52.1×10^3 (M(subscript r)) Homology analysis showed that the deduced amino acid sequence of this cDNA exhibited high identity to the plastidial ω3-fatty acid desaturase. RT-PCR analysis indicated that this plastidial ω3 desaturase had a constitutive expression in the leaf of J curcas. In this study, the function of this putative desaturase was identified by heterologous expression in Saccharomyces cerevisiae strain INVScl. The analysis of the fatty acids of yeast transformants showed thatα-linolenic acid was accumulated in the yeast. These results suggest that this cDNA encodes a plastidial ω3-fatty acid desaturase in J curcas.