Lesquerella, a Potential New Oilseed Crop for Producing Industrial Bio-Products.

Lesquerella (Physaria fendleri) is valued for its unusual hydroxy fatty acid (HFA) in seed and is a new industrial oilseed crop in the southwestern US. HFA and its derivatives are used as raw materials for numerous industrial products, such as lubricants, plasticizers and surfactants. The majority of HFA in lesquerella is lesquerolic acid (20:1OH) comprising 55-60% of seed oil. Castor (Ricinus communis) is the conventional source of HFA, and 90% of castor oil is ricinoleic acid (18:1OH). The production of castor oil, however, is hampered by the presence of the toxin ricin and hyper-allergic 2S albumins. Lesquerella, on the other hand, does not have such biologically toxic compounds, thus its oil represents a safe source of HFA. Biotechnology methods are effective for improving lesquerella through Agrobacteria-mediated genetic transformation. Lesquerella seed developmental studies show changes of morphology and physiology, as well as temporal details of fatty acid composition and gene expression patterns. Synthesis of 20:1OH is through elongation of 18:1OH, and the step is regulated largely by gene transcription of an elongase, PfKCS3. By silencing PfKCS3, transgenic lesquerella increased 18:1OH content from ~3% to ~27%. It is known that most of the HFAs in lesquerella are located only at sn-1 and sn-3 positions of triacylglycerols (TAG). To improve HFA levels in lesquerella seeds, a castor lysophosphatidic acid acyltransferase 2 gene (RcLPAT2) capable of acylating HFA to the sn-2 position of TAGs was introduced into lesquerella. The resulted transgenic lesquerella seeds increased 18:1OH content at the sn-2 position of TAG from 2% to 17%, and consequently, oil accumulated more TAGs with all three sn positions occupied by HFA. The results enhanced our understanding of plant lipid metabolism and provided invaluable guidance for future research, not only for enhancing HFA content in lesquerella, but also for HFA production in other oilseed crop.