Plants acquire resistance to pests through genetic engineering by introducing specific genes that produce proteins or compounds capable of deterring, killing, or disrupting the growth and reproduction of harmful insects or pathogens. This process enhances the plant’s natural defense mechanisms and reduces the need for chemical pesticides.
Here’s how it works step by step:
- Identification of Resistance Genes:
Scientists first identify genes from other organisms — such as bacteria, viruses, or other plants — that produce pest-resistant compounds. For example, the Bacillus thuringiensis (Bt) bacterium produces a protein toxic to certain insect larvae. - Insertion of the Gene into the Plant Genome:
The selected resistance gene (like the Bt gene) is inserted into the plant’s DNA using transformation methods such as Agrobacterium-mediated transformation or biolistics (gene gun). - Expression of Resistance Protein:
The introduced gene instructs the plant cells to produce the protective protein throughout the plant or in specific tissues (like leaves or stems). When the pest feeds on the plant, it ingests this protein. - Mode of Action Against Pests:
- In Bt plants, the Bt toxin binds to receptors in the insect’s gut, creating pores in the gut wall and causing the pest to stop feeding and die.
- Some genes produce protease inhibitors or enzyme blockers that interfere with insect digestion.
- Others enhance plant secondary metabolites that act as natural repellents or toxins.
- Development of Transgenic Pest-Resistant Crops:
Common examples include:- Bt cotton – resistant to bollworms.
- Bt corn (maize) – resistant to European corn borer and other insects.
- Bt brinjal (eggplant) – resistant to fruit and shoot borer.
- Benefits:
- Reduces dependence on chemical pesticides.
- Increases crop yield and quality.
- Protects beneficial insects and promotes sustainable farming.
- Precautions:
To prevent pests from developing resistance, refuge crops (non-Bt plants) are planted nearby, and gene stacking (introducing multiple resistance genes) is often used.
In summary:
Through genetic engineering, plants acquire pest resistance by integrating genes that produce natural insecticidal or defensive proteins, giving them built-in protection against harmful pests and improving agricultural productivity.