Lecture 4 Flashcards
EU de facto moratorium on new products.
1998 to 2004
WTO action 2003
Lisbon 2000: “Europe the most competitive knowledge-based economy in the world by 2010”
New legislation for GM food and crops
Precautionary Principle embedded
GM Food & Feed: Labelling and Traceability, 2003
Thresholds: 0.9% in foods
UK 2005-2012
Under European Union (EU) legislation, genetically modified organisms (GMOs), including GM crops, can only be released into the environment if a science-based risk assessment shows that safety will not be compromised
Current status in EU zone
2 types of GM authorised for use in EU:
1. insect resistant maize
2. Potato w/ modified starch content for industrial use
Neither of these is relevant or suitable for production in the UK. In 2011, the maize was grown on 114,490 hectares in 6 EU countries and the potato was grown on 17 hectares in 2 countries.
2011 GLOBAL GM CROPS STATS
2011 globally GM crops were grown by around 16.7 million farmers in 29 countries. The area grown has increased steadily year-on-year, reaching about 160 million hectares in 2011. This represents an 8% increase in the number of farmers and the area grown since 2010.
Timeline to introduce GM:
- Identify genes
- transfer genes to crop plants
- field test for efficacy and envirnmental impact
- regulatory testing submissions or approvals.
- Certified seed manipulation.
- Launch
Stacked
two or more combined traits have increased in prevalence for example 63 and 78% of GM corn and cotton respectively grown
ENVIRONENTAL CONCERNS
The main environmental concerns about genetically modified (GM) crops are the potential weediness or invasiveness in the crop itself or in its wild or weedy relatives as a result of transgene movement. An evaluation of weediness and invasive traits that contribute to the success of agricultural weeds and invasive plants was of limited value in predicting the effect of biotic and abiotic stress tolerance GM traits, suggesting context-specific evaluation rather than generalizations. Useful ecological models exist predicting the effects of gene flow and altered fitness in GM crops and wild/weedy relatives, as well as suitable mitigation measures. A better understanding of factors controlling population size, dynamics, and range limits in weedy volunteer GM crop and related host or target weed populations is necessary before the effect of biotic and abiotic stress-tolerance GM traits can be fully assessed.
Impact of GM crops on the environment: establishment of novel weeds via gene transfer
Conclusions: Gene flow occurs with a noticeable frequency from cultivated rice to its weedy and wild relatives, and this might cause potential ecological consequences. It is recommended that isolation zones should be established with sufficient distances between GM rice varieties and wild rice populations to avoid potential outcrosses. Also, GM rice should not be released when it has inserted genes that can significantly enhance the ecological fitness of weedy rice in regions where weedy rice is already abundant and causing great problems.
2004 Annals of Botany Company
Bt crop impacts on plant beneficial
insects
Pros: Massive reduction in insecticide use –China up to 80% reduction foliar insecticide in Bt cotton benefits man and the environment
Cons: Escalation in usage esp Bt maize, cotton,
Potato, tobacco, soybean, rice, oilseed rape
Poorly studied impacts on non-target groups, field experiments difficult to do, no real organised long-term monitoring.
Regulation not coordinated or specific, no regulation at all in some countries. Need for protocols. Problems of resistance due to overexposure.
Strategies for improving baculoviruses
Selection of most pathogenic naturally occurring isolate/genotype
Gene deletion
Insertion of an insect gene
Insertion of a viral gene
Insertion of a foreign insecticidal toxin gene
Improved safety by reducing survival in environment
Life cycle of baculovirus
- polyhedron contains environmentally stable occluded virus
- insect ingests polyhedra on contaminated leaf
- occlusion derived iris is released in gut by alkaline digestion of polyhedron matrix and nucleocapsid infects midgut epithelial cells
- infected host insects climb to top of plant and die rupture and release new polyhedra to the environment
Scorpion Toxin AaIT
-the AaIT toxin binds with affinity to insect neutrons- death is due to disruption of the nervous system rather than from massive viral infection .
Safety of recombinant baculoviruses
In vertebrates – no evidence toxicity, allergic response or pathogenicity (humans, fish, birds amphibians).
Safe for humans – 70kg male given 10-100xs the acre field rate
Wild type occur in environment 2x106 polyhedra/sq inch cabbage (non-epizootic) and 7 x 107 /sq inch in epizootic plot (one serving coleslaw contains ~ 1.12 x 108 polyhedra).
The toxins expressed in Sf larvae were fed to predatory wasps with no adverse effect
Non-target arthropods not affected by recombinant virus sprays
Out-competed when in the presence of wt virus even in a ratio of 10:1 – reduced yield of virus
Summary
Baculoviruses offer an attractive alternative to chemicals
Genetically modified baculoviruses are more competitive with insecticides
Cell culture needed to produce recombinant viruses
Viruses will be needed when the GM plants cause resistance in the pests
Still a long way to go with public acceptance and regulation
