Agrobacterium-Mediated Transformation for Insect-Resistant Plants
Bacillus thuringiensis (Bt) is considered as gram-positive, aerobic, spore-forming, naturally occurring facultative soilborne bacterial pathogen and has been used for natural insect control. It produces a parasporal, persistent insecticidal protein crystals (ICPs). These ICPs are toxic in nature for a class of lepidopterans, dipterans, and coleopterans. That toxic protein differs, depending on the subspecies of Bt producing it. The most prevalent ICPs are the Cry (crystal) protein, and the other is Cty (cytolytic) protein produced by some Bacillus thuringiensis stains. The Cry proteins, in general were cleaved by proteolytic enzymes on intake to produce active toxins which results in osmotic imbalance, lysis of epithelial cells, and finally death due to starvation, whereas Cty proteins release vegetative insecticidal proteins (VIPs) which lead to membrane disruptions, midgut lysis, and paralysis in lepidopterans pests. The use of ICPs as a pesticide or insecticide over chemicals is more beneficial as there is less amount of environmental pollution and harmful chemical residues leaching into the soil and water bodies. It is also target specific and acts on specific class of pests and at the same time harmless to birds, fish, and mammals whose acidic gut conditions negate the bacteria’s effect.
KeywordsBacillus thuringiensis (Bt) Insecticidal Protein crystals (ICPs) Major pests Cultivated crops
The authors would like to thank authorities of Annamalai University and VIT School of Agricultural Innovations and Advanced Learning, Vellore, for their encouragement and support.
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