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