Specialized lysophosphatidic acid acyltransferases contribute to unusual fatty acid accumulation in exotic Euphorbiaceae seed oils

Authors: Shockey, Jay; LAGER, IDA - Swedish University Of Agricultural Sciences; STYMNE, STEN - Swedish University Of Agricultural Sciences; KOTAPATI, HARI KIRAN - University Of Southern Mississippi; SHEFFIELD, JENNIFER - University Of Southern Mississippi; Mason, Catherine; BATES, PHILIP - University Of Southern Mississippi

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2018
Publication Date: 1/4/2019
Citation: Shockey, J., Lager, I., Stymne, S., Kotapati, H.K., Sheffield, J., Mason, C., Bates, P.D. 2019. Specialized lysophosphatidic acid acyltransferases contribute to unusual fatty acid accumulation in exotic Euphorbiaceae seed oils. Planta. 1-15. https://doi.org/10.1007/s00425-018-03086-y.
DOI: https://doi.org/10.1007/s00425-018-03086-y

Interpretive Summary: One of the long-standing goals of the biotechnology community has been to develop the skills and technology needed to produce novel, bio-based environmentally kind alternatives to petrochemicals, either in microbes or plants. One of the major hurdles faced is a lack of knowledge of which genes have to be manipulated in the new hosts to achieve successful production of the novel compounds. Here we present the analysis of a type of vegetable oil synthesis gene found in a family of related plants. This category of gene is shown to play a large role in increasing total seed oil production levels in the new hosts, as well as increasing the amount of novel components in the oil.

Technical Abstract: Many exotic Euphorbiaceae species, including tung tree (Vernicia fordii), castor bean (Ricinus communis), Bernardia pulchella, and Euphorbia lagascae, accumulate unusual fatty acids in their seed oils, many of which have valuable properties for the chemical industry. However, various adverse plant characteristics including low seed yields, production of toxic compounds, limited growth range, and poor resistance to abiotic stresses have limited full agronomic exploitation of these plants. Biotechnological production of these unusual fatty acids (UFA)in high yielding non-food oil crops would provide new robust sources for these valuable bio-chemicals. Previous research has shown that expression of the primary UFA biosynthetic gene alone is not enough for high-level accumulation in transgenic seed oils; other genes must be included to drive selective UFA incorporation into oils. Here we use a series of in planta molecular genetic, and in vitro biochemical experiments to demonstrate that lysophosphatidic acid acyltransferases from two Euphorbiaceae species have high selectivity for incorporation of their respective unusual fatty acids into the phosphatidic acid intermediate of oil biosynthesis. These results demonstrate that unusual fatty acid production arose in part via co-evolution of multiple oil biosynthesis and assembly enzymes that cooperate to enhance selective fatty acid incorporation into seed oils over that of the common fatty acids found in membrane lipids.