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Title: Current progress towards the metabolic engineering of plant oil for hydroxy fatty acids production

item LEE, KYEONG-RYEOL - Rural Development Administration - Korea
item Chen, Grace
item KIM, HUYN UK - Korean Rural Development Administration

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2014
Publication Date: 12/30/2014
Citation: Lee, K., Chen, G.Q., Kim, H. 2014. Current progress towards the metabolic engineering of plant oil for hydroxy fatty acids production. Plant Cell Reports. 34:603-615. DOI 10.1007/s00299-015-1736-6.

Interpretive Summary: Industrial uses of vegetable oils can be classified into two groups, biofuels and industrial chemical feedstocks. Biofuels, obtained by the methylation of the fatty acids (FA) in vegetable oils, are used for vehicle transportation and biojet aviation. The chemical feedstock FAs are used as additives or raw materials for numerous industrial products, including lubricants, inks, plastics, soaps, cosmetics, paints, coatings, and adhesives. Most of the FAs in vegetable oils are composed of palmitic acid (16:0), stearic acid (18:0), oleic acid (or 18:1), linoleic acid (18:2), and linolenic acid (18:3), the so-called “common” FAs. Some plants produce uncommon FAs with unique physical and chemical properties suitable for a specific industrial application, they are often called “unusual FAs”. Hydroxy FAs (HFAs) are among the most important industrially useful unusual FAs and can be widely used in industry as chemical feedstock. Research efforts have been focused on production of HFAs in transgenic plants using biotechnology. In this article, we discuss mostly the current metabolic engineering of plant oils for the production of HFAs and future perspectives.

Technical Abstract: Vegetable oil is not only edible but also can be used for industrial purposes. The industrial demand for vegetable oil will increase with the future depletion of fossil fuels and environmental problems such as climate change, caused by increased carbon dioxide in the air. Some plants accumulate high levels of unusual fatty acids in their seeds, and these fatty acids (FAs) have properties that make them suitable for industrial applications. Hydroxy fatty acids (HFAs) are some of the most important of these industrial FAs. Castor oil is the conventional source of HFA. However, due to the ricin toxin in its seeds, castor is not cultivated in a large scale. Lesquerella is another HFA accumulator and currently being developed as a crop for a safe source of HFAs. Mechanisms of HFA synthesis and accumulation have been extensively studied using castor genes and model Arabidopsis. HFAs accumulated to 17% in the seed oil of Arabidopsis expressing a FA hydroxylase gene from castor (RcFAH12), but its seed oil content and plant growth decreased. When RcFAH12 gene was coexpressed with additional castor gene(s) in Arabidopsis, higher levels of HFAs were accumulated and the seed oil content and plant growth was almost restored to the wild-type level. Therefore, more genes involved in HFA synthesis need to be tested in transgenic plants. Lesquerella and Physaria lindheimeri which also accumulates HFA, provide excellent genetic sources for discovering more target genes. Camelina, which is an existing industrial oilseed crop, has potential to host HFA production.