Characterization of Arabidopsis mutants that are associated with altered C18 unsaturated fatty acid metabolism

Abstract

Polyunsaturated fatty acids are a major component of glycerolipids in plant cellular membranes. We have isolated four novel fatty acid mutants of Arabidopsis thaliana named regulator of fatty acid composition ( rfc) 1 through 4. The rfc1, rfc2 and rfc3 mutants had an increased oleic acid (18:1) level at the expense of α-linolenic acid (18:3) level among total fatty acids especially in root tissues. In these mutants, the transcripts of FAD2 and FAD3 gene for ER Δ12 and ω-3 fatty acid desaturases that are involved in the desaturation of 18:1 and linoleic acid (18:2), respectively, were accumulated to the wild-type levels. In the rfc4 mutant, over-accumulated 18:3 with a corresponding increase in the FAD3 mRNA over wild-type levels was observed. These results suggest that C18 unsaturated fatty acid metabolism in extra-plastid membranes is controlled by multiple loci in addition to the structural genes for fatty acid desaturases.