The impact of reducing fatty acid desaturation on the composition and thermal stability of rapeseed oil

Abstract

Summary Oilseed rape (Brassica napus) is the third largest source of vegetable oil globally. In addition to food uses, there are industrial applications that exploit the ability of the species to accumulate the very‐long‐chain fatty acid (VLCFA) erucic acid in its seed oil, controlled by orthologues of FATTY ACID ELONGASE 1 (Bna.FAE1.A8 and Bna.FAE1.C3). The proportion of polyunsaturated fatty acids (PUFAs) in rapeseed oil is predicted to affect its thermal stability and is controlled by orthologues of FATTY ACID DESATURASE 2, particularly Bna.FAD2.C5. Our aim was to develop rapeseed lines combining high erucic and low PUFA characters and to assess the impact on thermal stability of the oil they produce. The new type of rapeseed oil (high erucic low polyunsaturate; HELP) contained a substantially greater proportion of erucic acid (54%) compared with high erucic rapeseed oil (46%). Although the total VLCFA content was greater in oil from HELP lines (64%) than from high erucic rapeseed (57%), analysis of triacylglycerol composition showed negligible incorporation of VLCFAs into the sn‐2 position. Rancimat analysis showed that the thermal stability of rapeseed oil was improved greatly as a consequence of reduction of PUFA content, from 3.8 and 4.2 h in conventional low erucic and high erucic rapeseed oils, respectively, to 11.3 and 16.4 h in high oleic low PUFA (HOLP) and HELP oils, respectively. Our results demonstrate that engineering of the lipid biosynthetic pathway of rapeseed, using traditional approaches, enables the production of renewable industrial oils with novel composition and properties.

Heterogeneous Distribution of Erucic Acid in Brassica napus Seeds

“…Based on these results, it seems that both pathways could be contributing to the assembly of erucic acid-containing TAGs in WH3401, since the expression pattern of almost all the genes of both the TAG biosynthesis pathways suggests a more enrichment in the cotyledonary tissues, relative to the EA, which is consistent with the observed cotyledonary localization of erucic acid-containing TAGs in this accession. However, the affinity of native lysophosphatidic acid acyltransferase (LPAAT) is poor for fatty acyl chains with more than 18 carbons, implying C22:1 is difficult to incorporate into the sn-2 position of lipids by the Kennedy pathway (Lassner et al, 1996;Furmanek et al, 2014;Kaur et al, 2019) (Figure 5). This may suggest that LPCAT and PDAT help to compensate for this deficiency of LPAAT by introducing erucic acid into the sn-2 position of TAGs.…”

“…Brassica napus (AACC, 2n = 38) is an allotetraploid oilseed plant species formed by the hybridization of two diploid species of Brassica rapa (AA,2n = 20) and Brassica oleracea (CC, 2n = 18) about 7,500 years ago (Chalhoub et al, 2014;An et al, 2019). It is the third largest oil crop in the world and accounts for approximately 15% of the vegetable oil used for human consumption (Wells et al, 2014;Liu et al, 2016;Carruthers et al, 2017;Kaur et al, 2019). Like most oilseeds, triacylglycerols (TAGs) comprise 95% of B. napus seed oil which are composed of a glycerol backbone esterified with three fatty acyl chains (Ai et al, 2014;Guan et al, 2016).…”

“…In B. napus, there are six paralogs encoding FAE1 proteins (Qiu et al, 2006;Wu et al, 2008;Cao et al, 2010). BnaA8.FAE1 and BnaC3.FAE1 are the two major genes responsible for erucic acid synthesis in B. napus seeds and they elongate 18:1-CoA to 20:1-CoA, and then 20:1-CoA to 22:1-CoA (Furmanek et al, 2014;Kaur et al, 2019). These two genes are highly expressed in the seeds of high-erucic acid varieties and are minimally expressed in low-erucic acid varieties (Qiu et al, 2006;Cao et al, 2010).…”

Physiological and comparative transcriptome analyses reveal the mechanisms underlying waterlogging tolerance in a rapeseed anthocyanin-more mutant

“…Rapeseed ( Brassica napus ) is a main oil crop worldwide and has the largest cultivated area in China. Rapeseed oil contains high oleic acid, low saturated fatty acid, moderate linoleic acid, linolenic acid and many vitamins and sterols, which are important nutrient resources in edible vegetable oil [ 1 , 2 ]. In addition, the applications of rapeseed oil in chemical, pharmaceutical and bioenergy fields are increasing [ 3 , 4 ].…”

Association Mapping of Seed Quality Traits Under Varying Conditions of Nitrogen Application in Brassica juncea L. Czern & Coss

“…Palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), eicosenoic (C20:1), and erucic (C22:1) are the key fatty acids in this crop (Abbadi and Leckband, 2011). Breeding programs emphasize on providing varieties with both high (for industrial applications) and low (suitable for human consumption) erucic acid content (Beare-Rogers et al, 1971;Kaur et al, 2019). High oleic acid, low linoleic acid, or a combination of these have been developed in rapeseed-mustard crops (Appelqvist, 1971).…”