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United States Department of Agriculture

Agricultural Research Service

Research Project: Improvement and Utilization of Natural Rubber- and Castor Oil-producing Industrial Crops

Location: Crop Improvement & Utilization Research

Title: Metabolic Engineering oil biosyntesis pathways in Lesquerella Fendleri(Abstract)

Author
item Chen, Grace

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2012
Publication Date: N/A

Technical Abstract: Lesquerella fendleri (A. Gray) S. Wats. (Brassicaceae), being developed as a new industrial oilseed crop in the southwestern region of the United States, is valued for its unusual hydroxy fatty acid (HFA) in seed. The majority of HFA in L. fendleri is lesquerolic acid (14-hydroxy-eicos-cis-11-enoic acid: 20:1OH) comprising 55-60% of total seed fatty acids. The conventional source of HFA is from castor (Ricinus communis), 90% of castor oil is ricinoleic acid (12-hydroxy-octadec-cis-9-enoic acid: 18:1OH). Ricinoleic acid and its derivatives are used as raw materials for numerous industrial products, such as lubricants, plasticizers and surfactants. The production of castor oil, however, is hampered by the presence of the toxin ricin and hyper-allergic 2S albumins in its seed. L. fendleri, on the other hand, does not have such biological toxic compounds, thus its oil represents a safe source of HFA. Lesquerella oil contains 55-60% HFAs which is lower than that of 90% in castor oil. It is known that most of the HFAs in L. fendleri are located only at sn-1 and sn-3 positions of TAG. This suggests that it may be possible to enhance HFA accumulation in L. fendleri seeds by manipulating a lysophosphatidic acid acyltransferase (LPAT) that favors incorporation of hydroxy acyl groups at the sn-2 position. To facilitate a genetic approach, a seed specific napin promoter was fused to the LPAT2 gene from castor,and the resulting vector was used to transform L fendleri. Seeds of fifteen independent transgenic lines were analyzed for changes in fatty acid (FA) composition, HFA content and oil content. Compared with wild type, the common FA composition in seeds of transgenic lines remained unchanged. However, all transgenic lines showed increase in 18:1OH and densipolic acid (12-hydroxy-octadec-cis-9,15-enoic acid: 18:2OH) content. The percentage of 18:1OH and 18:2OH in combine kept at 1.2% in wild type, but varied from 1.5% to 4.8% among transgenic lines. With the increase of 18:1OH and 18:2OH, the third minor HFA, auricolic (14-hydroxy-eicos-cis-11,17-enoic acid: 20:2OH) acid, also increased slightly, from 2.7% in wild type to 3.5-3.7% in transgenic lines. It is noted that the major HFA 20:1OH content had 4-6% decrease in transgenic lines. The total HFA content and oil content in wild type parent was measured at 56% and 18%, respectively, while in transgenic lines the level ranged from 52-60% and 13-21% respectively. Although we did not observe a significant increase in total HFA content in transgenic lines carrying napin-LPAT2, the results will advance our understanding of the mechanisms underlying HFA synthesis and direct the exploration of other pathways involved in oil accumulation in L. fendleri.

Last Modified: 9/1/2014
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