Lesquerella species

Ricinoleic acid (i -12-hydroxy-9-cw-octadecenoic acid) (Fig. 6) accounts for 80-90% of fatty acids in castor oil (from Ricinus communis). It is found in other plant species and in the sclerotia of the ergot fungus Claviceps purpurea). Lesquerolic acid (i -14-hydroxy-ll-cw-eicosenoic acid), which is a C20 homolog of ricinoleic acid, occurs in Lesquerella species (up to 70% of total fatty acids). Isoricinoleic acid (i -9-hydroxy-12-cw-octadecenoic acid, or 9-OH 18 2 12c) is a major acid in the Wrightia species. In plants, several C16 and C18 mono, di, and trihydroxy fatty acids are stmctural components of cutin (a polyester constituent of plant cuticle). 

Plants of the Lesquerella species are characterized by the presence of the C20 bis-homologue of ricinoleic acid—lesquerolic acid—sometimes accompanied by other acids of the same type at lower levels ... 

Figure 1. Proposed scheme for the biosynthesis of hydroxy fatty acids in Lesquerella species.

Ricinoleic acid (D-12-hydroxyoctadec-cis-9-enoic acid), is an hydroxylated fatty acid which constitutes 85-90% of the seed fatty acids in castor bean plants (Ricinus communis L). This unusual fatty acid is also one of a series of related Hydroxy Fatty Acids (HFAs) produced in the seeds of Lesquerella species. In these species, which, like A. thaliana and rapeseed belong to the Brassicacae family, ricinoleic acid is generally a minor constituent. Major HFAs include densipolic (12-OH, 18 2 (3,9)), lesquerolic (14-OH, 20 1 (9)) and auricolic (14-OH, 20 2 (3,9)) acids. 

Ricinoleic acid is only one of four HFAs produced in transgenic seeds, which also accumulate densipolic, lesquerolic and a small amount of auricolic acid. This suggests that Arabidopsis and related Lesquerella species metabolize ricinoleic acid in a similar way. 

Hydroxy fatty acids are used for thickening greases and for improving the pliability of plastic covering materials. Domestic needs have been met primarily by imported castor oil. Lesquerella species are being explored for this purpose, with 70 percent 14-OH-C20 reported for L. gracilis oil, and 50 percent 12-OH-C18 diene for L. densipila oil. ... 

Dierig, D.A., Tomasi, P.M., Salywon, A.M., Ray, D.T., 2004. Improvement in hydroxy fatty acid seed oil content and other traits from interspecific hybrids of three Lesquerella species Lesquerella fendleri, L pallida, and L. lindheimeri. Euphytica 139, 199-206. 

Lesquerella oil is a lesser known, naturally hydroxylated seed oil that is derived from the genus Lesquerella. Of many different wild species, Lesquerella fendleri is currently the only species being developed for commercial evaluation [69]. The plant is native to the southwestern USA, and is typical in mildly alkaline, arid soils. Some attempts to investigate the adaptation of L. fendleri [70-72] to a wider enviromnent have indicated that the plant is not widely adaptable. Low adaptability, combined with difficult oil recovery and moderate acreage yield of the oil may be limiting factors in the broad commercial development of lesquerella oil. 

New oilseed crops, currently studied as potential sources of specialty fatty acids, include Crambe abyssinica for erucic acid, Limnanthes alba for very long-chain fatty acids, Dimorphotheca pluvialis for dimor-phecolic acid, Lesquerella fendleri for les-querolic acid, Calendula officinalis for calendic acid, and Euphorbia lagascae and various Vernonia species for vernolic acid.194 The lowest cost sources (inedible fats and oils and palm oil fractions) are likely most likely to be exhausted first as world trade in industrial applications grows. Cornstarch is becoming a major feedstock for plastics production. This may compete with potential oil uses, but also will increase production of com oil. 

The plant kingdom is estimated to offer >300,000 species available to man (1) of which only a few hundred are in organized agriculture. In 1957, the USDA initiated a program to collect >8000 different plant species, many of which were analyzed for potential sources of starch, protein, oil, fiber, medicinal components, as well as any other unusual materials. As a result of this effort, >100 new oils were discovered. Of these new oilseed plants, three have progressed to the point of commercial production, crambe, jojoba, and meadowfoam. In addition, lesquerella is almost sufficiently developed to begin production. The unique chemical structures of these four seed oils and how they affect the chemistry of the oil will be the basis of this chapter. 

Plant species of the genus Lesquerella are being developed as an alternative erop for the southwestern region of the U.S. The seed oil of Lesquerella contains 55-60% of 14-hydroxy-cw-11 -eicosenoic acid (lesquerolic acid), a homologue of ricinoleic acid obtained from castor oil (19). Chemical modifications of lesquerolic acid, thus far, have nearly duplicated derivatizations of ricinoleic acid. 

Members of the genus Lesquerella produce seed oils containing a high proportion of hydroxy fatty acids. There are three types of Lesquerella which are distinguished by the most abundant seed oil fatty acid - lesquerolic acid (20 1 OH), densipolic acid (18 20H) or auricolic acid (20 2OH), as represented by L. fendleri, L. kathryn and L. auriculata, respectively. We have investigated the conversion of radiolabelled intermediates of hydroxy fatty acid biosynthesis in the above three species. 

Lesquerella oil differs from castor in having nine methylene units before the double bond, rather than seven. Similarly, the structure of the predominant vernonia oil triglyceride, trivernolin, is shown below in Equation 2, where the functionality is around 2.4, depending on the exact species of vernonia, corresponding to a purity of about 80% trivernolin. 

Hayes, D.G., Kleiman, R., Phillips, B.S., 1995a. The triglyceride composition, structure, and presence of estolides in the oils of Lesquerella and related species. 1. Am. Oil Chem. Soc. 72, 559-569. 

Cruz, V.M.V., KiUan, A., Dierig, D.A., 2013a. Development of DArT marker platforms and genetic diversity assessment of the US collection of the new oilseed crop Lesquerella and related species. Plos One 8. 

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