Modification of Brassica Oil Using Conventional and Transgenic Approaches

Abstract

Modifying the fatty acid composition of Brassica seed oil to increase its value as a nutritional or as an industrial oil has been a major objective in Brassica breeding programs worldwide. The conventional approach to fatty acid modification has explored natural or induced mutations occurring in the same plant species or close relatives within the Brassica genus. These mutations have been shown to be associated with a few enzymes in the biosynthetic pathway of the fatty acids. Several types of Brassica oil with significantly altered levels of the long chain fatty acid erucic acid (C22:1) and medium chain fatty acids such as oleic acid (C18:1) and linolenic acid (C18:3) have been developed for different end uses through conventional breeding. When the necessary genetic variation is not available within Brassica species, gene transfer by genetic transformation has been applied, as this approach is not restricted by the sexual incompatibility barrier across species. The fatty acids targeted by the transgenic approach included fatty acids with various carbon chain lengths ranging from C8 to C22, with different numbers of double bonds, and with various functional groups such as epoxy and hydroxy fatty acids. A commercial specialty oil with high level of a novel fatty acid, lauric acid (C12:0), was produced as a result of the transfer of a FatB thioesterase gene from a distantly related plant species that produces seed oil with high level of this unusual fatty acid. Considerable progress has been achieved in altering the relative levels of the fatty acids found in Brassica oils for increased health and economic benefits and in developing Brassica oils which contain other unusual fatty acids, mainly through genetic transformation. Although the use of natural or induced mutations in the fatty acid biosynthesis within Brassica remains a valid option for oil modification, the transgenic approach will play an increasingly important role in the development of Brassica oils with altered novel fatty acid composition.

Abscisic acid metabolism and lipid accumulation of a cell suspension culture of Lesquerella fendleri

“…Wats., commonly referred to as desert mustard, produces seed oil high in hydroxy fatty acids (Carlson et al, 1990;Skarjinskaia 2003 ). Oils high in hydroxy fatty acids can replace castor oil, which is used extensively in industrial applications including cosmetics, plastics and coatings (Redd et al, 1997;Dykinga 1999) The quality of plant oils and their industrial value are determined by fatty acid content and composition (Scarth and Tang 2006). Both traditional plant breeding and genetic engineering have been employed to modify and improve oil content in oilseed crops (Holbrook et al, 1992;Perry and Harwood 1993;Scarth and Tang 2006;Jiang et al 2009;Taylor et al, 2009).…”

“…Oils high in hydroxy fatty acids can replace castor oil, which is used extensively in industrial applications including cosmetics, plastics and coatings (Redd et al, 1997;Dykinga 1999) The quality of plant oils and their industrial value are determined by fatty acid content and composition (Scarth and Tang 2006). Both traditional plant breeding and genetic engineering have been employed to modify and improve oil content in oilseed crops (Holbrook et al, 1992;Perry and Harwood 1993;Scarth and Tang 2006;Jiang et al 2009;Taylor et al, 2009). The successful development of such modulating strategies relies not only on selecting the appropriate plant line, but also on understanding the mechanisms regulating lipid biosynthesis and oil deposition as they relate to agricultural conditions and stresses.…”

Inheritance and variation of erucic acid content in a transgenic rapeseed (Brassica napus L.) doubled haploid population

“…Erucic acid (22:1) obtained from the seed oil of high erucic acid rapeseed (HEAR) is a sought-after raw material used by the oleochemical industry (Scarth and Tang 2006). It is used in the production of plastic films, nylon, lubricants and emollients.…”

Chinese cabbage (Brassica rapa ssp. pekinensis) – a valuable source of resistance to clubroot (Plasmodiophora brassicae)

“…In order to broaden the genetic base of crop species, different approaches could be employed. Species of Brassicaceae are especially amenable to genetic manipulation to improve oil type or to transfer other desired characters (Scarth and Tang 2006). Characterization is the first step was using available germplasm resources (McFerson 1998).…”