Cultivars of B. napus

Microspore-derived embryos from a low erucic acid B. napus cultivar (Topas) were also screened for the ability to biosynthesize triacylglycerols in vitro. In the presence of G-3-P, homogenates prepared from mid-cotyledonary stage MD Topas embryos incorporated erucoyl- and oleoyl moieties into triacylglycerols at equal rates (Fig. 13). Thus, the breeding effort which produced low erucic acid cultivars of B. napus did not adversely affect the capacity of such embryos to incorporate very long-chain fatty acids into triacylglycerols. Rather, such cultivars are impaired in the ability to biosynthesize eicosenoic and erucic acids. 

Fig. 13. Incorporation of C-oleoyl-CoA and C-erucoyl-CoA, 40 pM each, into triacyl-glycerols by homogenates of microspore-derived embryos of B. napus cv Topas (tow erucic acid cultivar) incubated in the presence and absence of200 pM G-3-P. The data are presented as pmoles labeled acyl moieties incorporated per min and mg protein. D. C. Taylor (unpublished data)...

Newkirk et al. (1997) found that broilers fed on B. juncea meals grew as quickly and converted feed to gain as efficiently to 21 days of age as those fed on B. napus and B. campestris meals. Feeding meal from B. campestris reduced growth rate and gain/feed ratio. They concluded that the nutritional value of meals from low-glucosinolate mustard is equal or superior to that of rapeseed meal samples derived from B. napus and B. campestris cultivars. 

The name canola was registered by the Western Canadian Oilseed Cmshers in 1978 and subsequently transferred to the Canola Council of Canada in 1980. It included those cultivars containing less than 5% emcic acid in the oil and 3 mg/g aliphatic glucosinolates in the meal. In 1986, the definition of canola was amended to B. napus and B. rapa lines with less than 2% emcic acid in the oil and less than 30 pmol/g glucosinolates in the air-dried, oil-free meal. The oil was added to the Generally Recognized as Safe (GRAS) list of food products in the United States. 

Long-term yield of camelina cultivars in North America has been averaging from 1100 to 1200 kg/ha with a maximum of about 2000 kg/ha. It should be noted that the yield of many commodity oilseeds, especially B. napus, has been improved through plant breeding, whereas camelina has not been modified yet (63). 

Oro was Canada s first B. napus low-erucic acid rapeseed cultivar, developed by Agriculture and Agri-Food Canada, Saskatoon, and released in 1968 (Stefansson and Downey 1995). Oro was developed by pedigree selection in the progeny from the cross of Nugget x Liho. It had an erucic acid concentration of less than 5% and a high glucosinolate concentration of over 150 pmol/g air-dried, oil-free meal. 

Hundreds of additional B. napus and B. rapa double-low rapeseed (canola) cultivars have been developed and released in Canada since the 1970s. These new double-low rapeseed (canola) cultivars have incremental improvements in agronomic performance or seed quality. 

Rapeseed and double-low rapeseed (canola) cultivars in Canada have traditionally been open-pollinated population cultivars in both B. nap us and B. rapa. More recently, hybrid 5. napus double-low rapeseed (canola) cultivars have been developed and released in Canada. Most of these hybrids are also herbicide tolerant. Nearly 50% of double-low rapeseed (canola) production in Canada in 2005 was of hybrid B. napus types (Brandt and Clayton 2005). This proportion increases annually. 

Beversdorf, W.D., J. Weiss-Lerman, L.R. Erickson, and V. Souza Machado. 1980. Transfer of cytopl asmical ly-inherited triazine resistance from bird s rape to cultivared oilseed rape (Brassica campestris L. and B. napus L.). Can. J. Genet. Cytol. 22 167. 

Based on our initial assessment of the relatively broad acyl specificity of yeast LPAT, and our interest in modifying the very long-chain fatty acid (VLCFA) content of Brassicaceae seed oils (4), we expressed the SLCl-1 gene in the model oilseed Arabidopsis thaliana, and in a high erucic acid B. napus cultivar. It will be shown that the yeast SLCl-1 gene can be used to change the content and composition of plant seed oils, via increased seed LPAT activity. 

Breeding for improved seed yield is the main breeding objective for HEAR cultivar development programs. Eor B. napus HEAR cultivars, this has involved, successively, selection within OPP landraces, crosses of OPPs and pedigree selection of derived families and hybrids (McVetty et al., 2009). 

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