Mutants of Arabidopsis with alterations in seed lipid fatty acid composition

Abstract

A diverse collection of mutants of Arabidopsis with altered seed lipid compositions was isolated by determining the fatty acid composition of samples of seed from 3,000 mutagenized lines. A series of mutations was identified that caused deficiencies in the elongation of 18∶1 to 20∶1, desaturation of 18∶1 to 18∶2, and desaturation of 18∶2 to 18∶3. In each of these cases the wild type exhibited incomplete dominance over the mutant allele. These results, along with results from earlier studies, point to a major influence of gene dosage in determining the fatty acid composition of seed lipids. A mutation was also isolated that resulted in increased accumulation of 18∶3. On the basis of the effects on fatty acid composition, the nature of the biochemical lesion in three of the mutants could be tentatively attributed to deficiencies in activities of specific enzymes. The other mutant classes had relatively less pronounced changes in fatty acid composition. These mutants may represent alterations in genes that regulate lipid metabolism or seed development. The availability of the mutants should provide new opportunities to investigate the mechanisms that control seed lipid fatty acid composition.

Alteration of Seed Fatty Acid Composition by an Ethyl Methanesulfonate-Induced Mutation in Arabidopsis thaliana Affecting Diacylglycerol Acyltransferase Activity

“…The ratio of 18:3/18:2 in AS11 seed was 1.39 2 0.02, whereas in WT seed, it was 0.65 2 0.01. In having an elevated 18:3/18:2 ratio, ASll is somewhat similar to a mutant J B l l (elal, enhanced linolenate accumulation; 18:3/18:2 ratio 1.04 -C 0.10) previously described by Lemieux et al (1990). However, in contrast to JBll, AS11 has a drastically reduced proportion of 20:l; in J B l l this fatty acid is unaffected.…”

On the role of a Lipid-Transfer Protein. Arabidopsis ltp3 mutant is compromised in germination and seedling growth.

“…In fact, eicosenoic acid has been used as a convenient marker to monitor TAG breakdown. 34,37 Figure 4B shows the TAG-fatty acid composition of the wild type and ltp3 mutant upon germination. It can be seen that after 5 d of germination the mutant exhibits a differential fatty acid profile compared to the wild type.…”

Selective gene dosage by CRISPR‐Cas9 genome editing in hexaploid Camelina sativa

“…A fad2 Camelina mutant was isolated from an EMS‐mutagenized Camelina population, but since only one FAD2 homeolog was inactivated, 18:1 levels reached only 27% of total seed fatty acids (Kang et al ., 2011). In Arabidopsis, several fad2 ‐deficient lines have been isolated either by chemical mutagenesis (James and Dooner, 1990, 1991; Lemieux et al ., 1990; Song et al ., 2010), T‐DNA insertions (Okuley et al ., 1994; Zhang et al ., 2012) or hpRNA (Stoutjesdijk et al ., 2002). Most of the lines showed oleic acid levels around 20%–26% in leaves and 50%–57% in seeds, and did not show strong phenotypes when grown under normal conditions (Lemieux et al ., 1990; Miquel et al ., 1993; Okuley et al ., 1994; Song et al ., 2010; Stoutjesdijk et al ., 2002; Zhang et al ., 2012).…”