Canola, Rapeseed, and Mustard: For Biofuels and Bioproducts - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 134

for biofuel production and for dielectric fluids in electrical transformers, while high
oleic acid canola oil is being developed for use in hydraulic equipment. Rapeseed
oil has been used as a lubricant, and high erucic acid rapeseed oil has been used as a
lubricant and for select chemical feedstock applications [ 13 ]. Recently, medium
erucic acid mustard oil and canola juncea oil have been deemed suitable for biofuel
production [ 14 , 15 ].
Canola/rapeseed/mustard oilseed species are currently the third largest source of
vegetable oil globally after palm and soybean [ 16 ]. Considerable research and
development effort throughout the world to develop new cultivars of canola/
rapeseed/mustard for biofuel and bioproducts is occurring currently. The research
and development focus in canola/rapeseed/mustard is on hybrid development,
agronomic performance, seed quality, disease resistance, and novel traits to provide
advantages for these oilseed crops in an intensely competitive global oilseed
market.
Taxonomy and Domestication
The Brassica plant genus belongs to the Brassicaceae family (formerly known as
the Crucifer family), which is a large family of substantial economic importance
throughout the world [ 17 ]. The Brassicaceae family contains 338 genera and over
3,700 cultivated or wild species [ 18 ]. This family is characterized by plants that
have conduplicate cotyledons and/or two-segmented siliques which contain seeds
in one or both chambers and only have simple hairs, if present [ 19 ].
Several species within the Brassica genus including B. carinata (Abyssinian
mustard), B. juncea (Indian mustard) and B. napus (oilseed rape), B. nigra (black
mustard), and B. rapa (turnip rape) are grown as oilseed crops. Brassica napus and
B. rapa species are classified as “rapeseed,” while B. carinata , B. juncea , and
B. nigra are classified as “ mustard.” While B. nigra was grown as an oilseed in
the past, it is currently grown exclusively as a condiment crop [ 20 ]. A closely
related species, B. oleracea (cabbage, kale, and cauliflower) is primarily a biennial
plant grown as a vegetable, not as an oilseed. All of these Brassica species naturally
produce long-chain fatty acids in their seed oil and defense-related secondary
metabolites called glucosinolates found throughout the entire plant [ 2 ].
Of these six Brassica species, three are diploids ( B. nigra , B. oleracea , and
B. rapa ), and three are amphidiploids ( B. carinata , B. juncea and B. napus ), which
combine the chromosome sets of the diploid species. The relationship among these
six Brassica species was first outlined by U in 1935 [ 21 , 22 ] (Fig. 7.1 ). U's triangle
describing the genomic relationship of these six Brassica species has greatly
facilitated interspecific breeding activities within the Brassica genus [ 23 ].
The three diploid Brassica species B. nigra , B. rapa , and B. oleracea are thought
to have arisen approximately 4-8 million years ago, while the three amphidiploid
species are very young in evolutionary terms, arising spontaneously in the last