Associate Professor Washington State University Pullman, WA, United States
Abstract: Hydroxylated fatty acids (HFA) have many uses within the chemical industry to produce a variety of lubricants, polymers, cosmetics, etc. The major source of HFA is castor beans which also accumulate the highly toxic protein ricin and has led to the desire for alternative sources of HFA. The bioengineering of HFA production in Brassicaceae seed oils has produced only relatively low levels of HFA in seeds. Additionally, HFA bioengineering commonly leads to reduced total oil accumulation due to bottlenecks in HFA flux through the overlapping metabolic network of membrane lipid and triacylglycerol assembly. Physaria fendleri is a non-toxic burgeoning oilseed crop native to the southwestern US that accumulates HFA to near 60% of seed oil. Our metabolic analysis indicated Physaria fendleri utilizes a novel triacylglycerol (TAG) remodeling pathway that naturally gets around the bottlenecks of HFA flux through membrane lipid intermediates that are present when engineering oilseeds to accumulate HFA in TAG. Characterization of P. fendleri acyltransferases and lipases demonstrated that the TAG remodeling enzymes are selective for substrate fatty acid composition and regiochemical structure, and that the in planta engineering of the acyl selective lipases can be utilized to increase both HFA and total oil accumulation in Physaria fendleri and other engineered oilseeds.
