C Kameswara Rao
Foundation for Biotechnology Awareness and Education
Bangalore, India
pbtkrao@gmail.com
1. Rapeseed (Brassica rapa) oil: Rapeseed oil, an industrial lubricant and a source of biodiesel in the temperate countries, was not suitable for human consumption, on account of its sharp taste due to glucosinolates (500μmol/g). Besides, it contains over 60% erucic acid linked to several ailments including cancer. In 1974, the Canadian plant breeders developed the Canola crop (Canadian Oil Low Acid) from the oil seed rape, genetically modified by conventional breeding techniques, to make it fit for human consumption. Canola, a great scientific and commercial success, has less than 2% of erucic acid and less than 30μmol/g of glucosinolates. It is projected as a healthier edible oil as it contains about 70% of mono-unsaturated fatty acids (MUFAs) such as oleic acid, more than most other edible oils. Canola seed cake is now used as cattle and poultry feed.
Development of Canola is a great achievement in altering the chemistry of an edible oil with enhanced health benefits. During the past two decades, genetically engineered (GE) varieties of Canola for resistance against a) pests, b) diseases, c) drought and d) herbicides, were developed to promote its wider cultivation and today 98% of all commercially cultivated Canola is GE for herbicide tolerance.
Several other developments make Canola an important and improved edible oil. The more significant among them are:
a) a GE Canola variety with lauric acid totally replacing oleic acid (Del Vichhio, 1996), makes the oil more resistant to rancidification, and reduces the need for hydrogenation which leads to the formation of the unhealthy trans-fatty acids;
b) producing Omega-3fatty acids in Canola using a gene from the fungus
Mortierella alpina (Ursin et al., 2000, 2003);
c) a transgenic Canola with 23% stearidonic acid, a more efficient precursor for the synthesis of the other Omega-3 fatty acids (James et al., 2003);
d) maximizing the accumulation of Omega-3 long chain-poly-unsaturated fatty acids (LC-PUFAs) (Kinney et al., 2004);
e) successful modification of fatty acid composition through a reconstitution of the biosynthetic pathways (Damude and Kinney, 2008) to develop a GE Canola containing high levels of stearic and linolenic acids;
f) The levels of lysine were enhanced in transgenic Canola (Falco et al.,
1995); and
g) High β-carotene levels were achieved in transgenic canola (Shewmaker et al., 1999; Ravanello et al., 2003).
2. Mustard (Brassica juncea) oil: Wu et al., (2005) developed a GE mustard with a significant increase in the levels of arachidonic acid (ARA) and eicosapentaenoic acid (EPA), though the accumulation of docosahexaenoic acid (DHA) was low.
Extracted from: Kameswara Rao, C., and Seetharam, A. (2017) Nutrient biofortification of staple food crops: Technologies, products and prospects. In: Phytonutritional improvement of crops.
Ed. N. Benkeblia. Wiley Blackwell, Chichester, U.K. Pp. 113-183. (in Press).
May 19, 2017.