GM & Herbicide Tolerance Flashcards
What do herbicides do?
Inhibit pigment synthesis
Inhibited amino acid synthesis
Inhibit photosynthesis
What crops are usually stacked and what are they stacked with?
Majority of GM maize and cotton are stacked with genes for:
- Herbicide tolerance (Ht)
- Insect tolerance (Bt)
What is glyphosate?
A herbicide with low toxicity that breaks down roots and rhizomes.
It breaks down quickly in the soil
When is glyphosate applied?
Applied post growth or pre emergence so it doesn’t get on crops
What are the pros and cons of low/no till agriculture?
+ Reduces soil erosion
+ Reduces fuel cost
+ Improves soil structure
- Can lead to increased herbicide usage
What GM herbicide resistant crops are there in the US?
Soybean
Cotton
Corn
Sugar beet (uptake is increasing rapidly)
How do gylphosates work?
Inhibits EPSPs, which slows the shikimic pathway, stopping amino acid synthesis.
How do you engineer resistance to herbicides?
Find EPSPs not inhibited by glyphosate
Engineer plants to contain this enzyme
What are the pros and cons of Herbicide resistant crops?
+ 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
What are some solutions to the cons of herbicide resistant crops?
GURTs - genetic use restriction technology
Multiple herbicides
GM plants resistant to other herbicides:
- Some plants degrade dicamba
- Transgenic soybean degrades synthetic auxin
What is the way forward for herbicide tolerance?
Best approach is integrates weed management:
- Reduced selection pressures
- Reduced resistant weeds
What are the claims about the toxicity of glyphosate?
IACR 2015: glyphosate is probably carcinogenic toward humans. Group 2A
European Food Safety 2015: Glyphosate is unlikely to pose carcinogenic hazards.
