Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 6/1/2008
Citation: Dyer, J.M., Mullen, R.T. (2008) Engineering plant oils as high-value industrial feedstocks for biorefining: the need for underpinning cell biology research. Physiologia Plantarum, (132):11-22. Interpretive Summary: Crude oil underpins all aspects of modern society by providing fuels for energy and raw materials for industry. In light of increasing costs of petroluem, decreasing world-wide production, increased environmental concerns with fuel usage, and the need to develop a domestically secure supply of energy and chemical feedstocks, it is essential that we develop alternatives to crude oil to maintain and enhance our way of life. Plants are well positioned to help meet this need since they are renewable and can provide both fuels (e.g., ethanol or biodiesel) as well as chemical feedstocks (starch, oils and protein). Plant oils, such as vegetable oils, will play a critical role in the emerging bioeconomy because they are chemically similar to the hydrocarbons in crude oil and therefore can be used directly in many fuel and industrial applications. In addition to the regular vegetable oils produced by domesticated oilseed crops, many wild plant species produce oils containing high amounts of “unusual” fatty acids in their seed oils that may have direct use in industry (e.g., plastics, coatings, resins, motor oil lubricants), and these oils represent high value products that can benefit both agricultural producers as well as industrial end users. Tapping into the robust biosynthetic machinery of plants to produce these valuable oils, however, requires significant research to understand the underlying mechanisms associated with their production. This manuscript provides an overview of the current impact of crude oil on society, describes an emerging model of biorefining where a variety of valuable products (e.g., fuels and chemicals) are derived from plants, and takes and in-depth look at the underlying molecular properties of enzymes that are involved in the production of high value industrial oils in plant seeds. The review will be helpful to those interested in biorefining, in general, as well as those scientists who are particularly interested in the production of value-added industrial oils in plant seeds.
Technical Abstract: Plant oils represent renewable sources of long-chain hydrocarbons that can be used as both fuel and chemical feedstocks, and genetic engineering offers an opportunity to create further high-value specialty oils for specific industrial uses. While many genes have been identified for the production of industrially important fatty acids, expression of these genes in transgenic plants has routinely resulted in a low accumulation of the desired fatty acids, indicating that significantly more knowledge of seed oil production is required before any future rational engineering designs are attempted. Here we provide an overview of the cellular features of fatty acid desaturases, the so-called diverged desaturases, and diacylglycerol acyltransferases, three sets of enzymes that play a central role in determining the types and amounts of fatty acids that are present in seed oil, and as such, the final application and value of the oil. Recent studies of the intracellular trafficking, assembly and regulation of these enzymes have provided new insights to the mechanisms of storage oil production, and suggest that the compartmentalization of enzyme activities within specific regions or subdomains of the endoplasmic reticulum may be essential for both the synthesis of novel fatty acid structures and the channelling of these important fatty acids into seed storage oils.