Biotechnology is widely used to develop disease-resistant plants by identifying, transferring, or modifying specific genes that help plants defend themselves against pathogens such as bacteria, viruses, fungi, and nematodes. This approach allows scientists to create crops that can resist diseases naturally, reducing the need for chemical pesticides and improving agricultural productivity in a sustainable way.
Here’s how biotechnology is used to develop disease-resistant plants:
- Genetic Engineering (Transgenic Approach):
- Scientists introduce genes from resistant plants, microorganisms, or other species into susceptible crops to confer resistance.
- These genes may code for proteins that inhibit pathogen growth or activate the plant’s defense mechanisms.
- Example: The Bt gene from Bacillus thuringiensis produces a toxin that protects plants like cotton and maize from insect pests.
- Pathogen-Derived Resistance (PDR):
- In this method, genes or genetic material from the pathogen itself are used to make the plant resistant.
- For example, inserting a viral coat protein gene into plants can prevent viral replication and infection.
- Example: Papaya ringspot virus-resistant papaya was developed using this technique, saving the papaya industry in Hawaii.
- RNA Interference (RNAi) Technology:
- This technique silences specific genes of the pathogen that are essential for its survival or infection process.
- When the pathogen infects the plant, the RNAi mechanism degrades the pathogen’s RNA, stopping disease development.
- Example: RNAi-based bananas resistant to Banana bunchy top virus have been developed using this method.
- CRISPR-Cas9 Genome Editing:
- This modern gene-editing tool allows precise modification or deletion of plant genes that make them susceptible to pathogens.
- It can also be used to insert new resistance genes from other species without introducing foreign DNA.
- Example: CRISPR-edited rice and tomatoes have been developed with improved resistance to bacterial blight and fungal diseases.
- Marker-Assisted Selection (MAS):
- DNA markers linked to disease-resistance genes are used to identify and select resistant plants during breeding programs.
- This speeds up the development of resistant varieties without directly modifying the genome.
- Example: MAS has been used to develop rice varieties resistant to blast and bacterial blight diseases.
- Use of Antimicrobial Proteins and Enzymes:
- Genes that code for antifungal or antibacterial proteins (like chitinases and glucanases) are introduced into plants to degrade pathogen cell walls.
- These proteins strengthen the plant’s natural defense system.
- Induced Systemic Resistance (ISR):
- Some beneficial microbes introduced through biotechnology trigger the plant’s own immune system to resist multiple pathogens.
- Example: Pseudomonas fluorescens bacteria are known to induce disease resistance in several crops.
- Tissue Culture and Somaclonal Variation:
- Through tissue culture, scientists can select naturally occurring variants (somaclonal variants) that show disease resistance and use them for crop improvement.
Examples of Disease-Resistant GM Crops:
- Bt cotton – resistant to bollworm.
- Papaya – resistant to papaya ringspot virus.
- Potato – resistant to late blight.
- Tomato – resistant to leaf curl virus.
- Rice – resistant to bacterial blight and blast disease.
In summary:
Biotechnology helps develop disease-resistant plants by manipulating genes responsible for defense, silencing pathogen genes, or enhancing natural resistance mechanisms. This results in crops that are more resilient, require fewer pesticides, and produce higher yields — contributing to sustainable and eco-friendly agriculture.