Identification of a novel pathway to produce valuable industrial oil in Lesquerella
Primary author: Sajina Bhandari
Faculty sponsor: Philip Bates
Primary college/unit: Agricultural, Human and Natural Resource Sciences
Plant oils containing hydroxy fatty acids (HFAs) are valuable alternative to petroleum for making cosmetics, lubricants, polymers and biofuels. The major source of HFAs is Castor but U.S. cultivation is banned due to seed toxins. Lesquerella is native to southwest U.S., non-toxic and produces HFA, but it needs to be further bred or engineered to be a high yielding alternative crop. The main goal of this project is to determine the pathway for oil/triacylglycerol (TAG) assembly in Lesquerella to aid in breeding/engineering approaches of crop development. Castor uses a linear pathway to make HFA-TAG directly, whereas other oilseed crops produce non-HFA-TAG from the membrane lipid phosphatidycholine (PC). But, most plants keep unusual fatty acids like HFA away from membrane lipids, making it unlikely that PC is a precursor to HFA-TAG. However, transcriptomics in Lesquerella indicated lipid gene expression was similar to plants utilizing the PC pathway, making the oil biosynthetic pathway unclear. Therefore, a biochemical isotopic labeling approach and protein-protein interaction studies were used to identify the oil biosynthetic pathway. Metabolic tracing of Lesquerella oil biosynthesis indicated a PC pathway producing TAG with 0-1-HFA but the HFA did not traverse the membrane. Over time 0-1HFA-TAG was converted to 2HFA-TAG. Thus, Lesquerella uses a novel TAG remodeling pathway that changes the oil composition after initial synthesis. Our protein-protein interaction studies have identified gene candidates that may be key to engineering unusual fatty acid accumulation in crop plants as an alternative to petroleum.