Establishment of Genetically Modified Crops GMC

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Establishment of Genetically Modified Crops (GMC)

• Recent advances in the transformation of
  plantsG. Hansen, M.S. Wright, TIPS, 1999 (4) 6
  p.226-231
• Excision of selectable marker genes from
  transgenic plants P.D. Hare, NH Chua, Nature
  Biotechnology, 2002, p. 575-580

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Why to genetically modify plants?

• increasing resistance against diseases
• increasing resistance against pests
• increasing resistance against environmental
  stress
• seed quality
• pharmaceutical production
• vaccine production

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Properties of GMC

• easy to establish
• effective transformation rates
• reproducible
• cost effective
• save no geneflow into not-transgenic plants or
  cross pollination with not-transgenic plants

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Main steps in production of transgenic plants

• identification and cloning the gene of interest
  (unrelated plant, completly different species)
• transformation
• tissue culture
• breeding of transgenic plant
• crossing with high productive crop species

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Techniques for plant transformation

• microinjection
• microprojectiles
• electroporation
• plant pathogenes Agrobacterium tumefaciens

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Agrobacterium tumefaciens
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Tissue culture

• from totipotent plant cells to embryos and organs
• protoplasts from single cells (no chimerism)
• shoots from various plant tissues

Callus and shoots from soybean (TIPS 1999).
Callus from maize (TIPS 1999).
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Selectabel markers

• differentiate transgenic from not-transgenic
• genes coding for resistance (antibiotics,
  herbicides)
• not-transgenic plants/cells killed, metabolic
  advantage to transgenic cells

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Selectabel markers

• unnecessary in already field grown plants
• remove selectable markers after they have served
  their function

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Removal of selectable markers

• segregation by integration into transposable
  elements
• use recombinase systems (Cre, FRT, RS)
• chromosomal rearrangement
• DNA deletions
• restricted recombinase
• activity by inducible system

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STATE 2002
Transgenic crop production area by country
(source James, 2000b) Country Area planted in
2000 (millions acres) Crops grown USA 74.8 soyb
ean, corn, cotton, canola Argentina 24.7 soybe
an, corn, cotton Canada 7.4 soybean, corn,
canola China 1.2 cotton South Africa 0.5 corn,
cotton Australia 0.4 cotton Mexico minor cotton
Bulgaria minor corn Romania minor soybean,
potato Spain minor corn Germany minor corn Franc
e minor corn Uruguay minor soybean
herbicide tolerance or insect pest-resistance from
http//www.colostate.edu.
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Benefits and risk of GMCs

• resistance against pests, environment
• higher production rates
• more useful and productive crop varieties are
  generated
• reduced use of pesticide

• antibiotic resistance (of wt species)
• crop to wt gene flow
• damage to human health
• leakage of GM proteins into soil

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