GM & Herbicide Tolerance Flashcards

1
Q

What do herbicides do?

A

Inhibit pigment synthesis
Inhibited amino acid synthesis
Inhibit photosynthesis

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2
Q

What crops are usually stacked and what are they stacked with?

A

Majority of GM maize and cotton are stacked with genes for:
- Herbicide tolerance (Ht)
- Insect tolerance (Bt)

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3
Q

What is glyphosate?

A

A herbicide with low toxicity that breaks down roots and rhizomes.
It breaks down quickly in the soil

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4
Q

When is glyphosate applied?

A

Applied post growth or pre emergence so it doesn’t get on crops

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5
Q

What are the pros and cons of low/no till agriculture?

A

+ Reduces soil erosion
+ Reduces fuel cost
+ Improves soil structure
- Can lead to increased herbicide usage

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6
Q

What GM herbicide resistant crops are there in the US?

A

Soybean
Cotton
Corn
Sugar beet (uptake is increasing rapidly)

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6
Q

How do gylphosates work?

A

Inhibits EPSPs, which slows the shikimic pathway, stopping amino acid synthesis.

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7
Q

How do you engineer resistance to herbicides?

A

Find EPSPs not inhibited by glyphosate
Engineer plants to contain this enzyme

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8
Q

What are the pros and cons of Herbicide resistant crops?

A

+ Reduced soil tillage
+ Herbicides can be sprayed post emergence
- Transfer of genes to weeds
- Crops can become weeds
- Increased selection pressure leads to weed resistance
- May affect wildlife

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9
Q

What are some solutions to the cons of herbicide resistant crops?

A

GURTs - genetic use restriction technology
Multiple herbicides

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10
Q

GM plants resistant to other herbicides:

A
  • Some plants degrade dicamba
  • Transgenic soybean degrades synthetic auxin
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11
Q

What is the way forward for herbicide tolerance?

A

Best approach is integrates weed management:
- Reduced selection pressures
- Reduced resistant weeds

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12
Q

What are the claims about the toxicity of glyphosate?

A

IACR 2015: glyphosate is probably carcinogenic toward humans. Group 2A
European Food Safety 2015: Glyphosate is unlikely to pose carcinogenic hazards.

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