Oilseed Rape

1
Oilseed Rape

• Oilseed Rape Brassica napus
• Wild relative Brassica rapa
• Belongs to Cruciferae ? family includes
  cabbage, cauliflower, brussel sprouts, turnip,
  swede, radish and mustard
• Crop used for production of vegetable oil and
  diesel fuel
• Pressed seed important component of animal
  feed
• Competition from weeds ? grasses easily
  outcompete oilseed rape ? use of herbicides
  necessary ? oilseed rape prime candidate for
  genetic modification

2

• Genes that give herbicide tolerance
• Insertion of
• pat- and bar- genes ? encode resistance to
  phosphinothricin
• epsps gene ? encodes resistance to
  glyphosate
• oxy- gene ? encodes tolerance to oxynil family
  of herbicides
• Other genetic modifications
• transesterase gene ? to alter the fatty acid
  content of the oil
• phytase gene
• ? to reduce the level of antinutrients in
  animal feed

3

• Transgenic lines of oilseed rape
• 17 lines have been accepted in 1995- 1999
• 3 not modified to express herbicide tolerance
• 4 carry genes that modify fertility and genes
  that confer herbicide tolerance
• 10 able to pass on herbicide tolerance trait to
  plants with which they breed
• ? problem oilseed rape forms hybrids with wild
  relatives
• ? hybrids mate with GM B. napus
• ? offspring would express tolerance phenotype
  ?agricultural management of hybrids more
  difficult
• ? gene stacking inevitable ? result plants
  that exhibit tolerance to multiple herbicides

4

• Coexistence of GM with conventional and organic
  crops
• difficult to achieve a low treshold of GM
  presence on farms where both GM and conventional
  oilseed rape crops are grown
• Gene flow not only problem confined to the
  movement of transgenic material
• ? oil from certain varieties inedible because of
  high levels of erucic acid and glucosinolates
• ?in conventional breeding programs development
  of plants that produce double- low oil
• ? contamination of double low oilseed crops with
  pollen from high erucic varieties can result in
  offspring with 2 erucic acid ? not for
  consumption
• ?field studies in two growing seasons?
  contamination between edible and high-
  level-erucic acid-crops no major problem under
  field-scale cultivation conditions

5

• Farm-scale evaluations of GM crops in UK
• 3 crops chosen oilseed, maize and beet
• Studies of ecological effects of GM crop,
  highlighting potential impact on amount of
  insects and weeds
• nationwide, 3 growing seasons
• Hypothesis For each of the 3 crops, there are no
  differences at field-scale level between
  biodiversity associated with GM crops and that
  associated with conventionally bred crops

6

• Report of Wilkinsons group
• ? contribution to debate on potential for gene
  flow from conventional oilseed rape crops into
  natural Brassica populations
• ? in the UK hybrid formation is likely to
  occur at a rate higher than that indicated by
  smaller scale studies
• ? higher rate of concern because most
  herbicide-tolerant oilseed rape lines do not
  contain of mechanisms to regulate the fertility
  of GM plants
• ? important to compare study with results from
  farm-scale evaluations
• ? studies can help to reinforce risk analysis
  in this area of public interest