Specificities and selectivities of enzymes involved in seed oil biosynthesis and how these properties relate to oil content and composition.

The fatty acid composition of the seed oil is important for its nutritional value as well as for its non-food application and can vary drastically between plant species.

The relative activities and specificities of the enzymes involved in oil accumulation have co-evolved to give an oilseed its particular oil composition.

Changing oil composition by changing individual enzyme activities often lead to an imbalance in fatty acid synthesis contra utilization in oil accumulation, with a decreased oil content of the seed as a consequence. Diacylglycerol acyltransferase enzymes (DGATs) catalyze the last step in oil biosynthesis.

Substrate specificities of DGATs have to match the fatty acid profile produced by the seed cell to avoid the lower oil content of the seed.

I will investigate the DGAT properties from three Brassicaceae species relevant to Swedish agriculture; rapeseed, turnip rape and field cress (a wild species under domestication).

I will study two varieties of each species that have radically different seed oil compositions, one with high erucic acid and one lacking this fatty acid. I will also study DGAT enzymes in Arabidopsis, a model plant for seed oil biosynthesis.

The results will show if and how DGAT isoforms adjust to the novel oil composition and identification of DGAT isoforms that can improve oil content in our oil crops by various breeding methods. The results will also increase our general understanding of seed oil biosynthesis.