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Need for engineering resistance
Biopesticides
Engineering Strategy
Strategies for engineering and types
Bacillus thuringiensis
Mechanism of action Bt toxin
Cry protein domains and functions
First experiment
Others
Initial problems and challenges
Modifications (bacterial genes in plants)
BT transgenics
Transgenics and organisms
European cornborer
European cornborer and Bt
Newer Bt transgenics have
Bt Corn: Commercially available
Bt Cotton/India
Impact of Bt use
Potential Environmental Concern
Monarch Butterfly debate
Losey et al., 1999
Bt transgenics/ indirect benefits
Plant derived antifeedants
antifeedants are
Agglutinins:
GNA (Galanthus nivalis agglutinin)
Agglutinins:
ASAL- Allium sativum (onion) leaf agglutinin- resistance against sap-sucking insects
Yarasi et al., 2008
Anderson et al., 2004 Emerging diseases proportions
Mayse and Price, 1978
Pathogen Derived Resistance
Cassava mosaic disease: important in developing countries
Examples of Viral diseases
Losses, viral diseases
Others
Engineering resistance
Resistance genes-
Resistance genes
Resistance genes transfer
Examples of natural transfer of R genes
Recessive resistance genes
Recessive Resistance: knocking out susceptibility genes
Coat protein mediated: TMV
coat protein-mediated
GM Resistance to Papaya Ringspot Virus in Papaya
Dennis Gonsalves 1978
Transgenic PRSV-resistant rainbow cultivars
Replicase and Movement Protein
Maize streak virus-resistant transgenic maize, first for Africa; Shepherd et al., 2007
RNA-mediated Resistance
RNAi mediated resistance to Cassava brown streak Uganda virus in Cassava
Yadav et al., 2011
Antibody-mediated Resistance
Safarnejad et al., 2011
Other non-conventional: Ribosomal inactivating proteins and protease inhibitors
Engineered virus resistant crops that have potential for release in developing countries
TILLING
