Q.32 One of the major drawback of transgenic plants/crops is
1. They are often observed to be less productive
2. They are more prone for diseases
3. They may indulge in unwanted horizontal spread of transgene
4. They often produce poor quality of seeds
Major Drawback of Transgenic Plants: Horizontal Gene Spread Explained
Transgenic plants, also known as GM crops, face scrutiny for potential risks despite their benefits like pest resistance. The correct answer to the query is option 3: They may indulge in unwanted horizontal spread of transgene, a key concern in biotechnology exams and research.
Correct Answer
Option 3: They may indulge in unwanted horizontal spread of transgene.
Horizontal gene transfer (HGT) from transgenic plants to wild relatives, microbes, or soil bacteria poses a significant environmental risk. This unintended spread can create “superweeds” or alter microbial ecosystems, making it a primary regulatory concern in GM crop approvals.
Option Analysis
Option 1: Less Productive
Transgenic crops are engineered for higher yields, pest resistance, and stress tolerance, often outperforming conventional varieties. Studies show no consistent evidence of reduced productivity; instead, they boost output in many cases.
Option 2: More Prone to Diseases
GM plants typically gain disease or pest resistance through traits like Bt toxin, reducing vulnerability. Risks involve secondary effects like pest resistance development, but they are not inherently more disease-prone.
Option 3: Unwanted Horizontal Spread (Correct)
This is the major drawback, as transgenes can transfer via pollen to wild plants or through DNA uptake by bacteria, potentially disrupting biodiversity and creating hard-to-control weeds. Field trials monitor this low-frequency but high-impact event.
Option 4: Poor Quality Seeds
Transgenic seeds maintain or improve quality, with traits like herbicide tolerance aiding hybrid vigor. Terminator genes prevent unauthorized saving, but seed quality itself is not compromised.
| Option | Statement | Correct? | Reason |
|---|---|---|---|
| 1 | Less productive | No | Engineered for higher yields |
| 2 | More prone to diseases | No | Often more resistant |
| 3 | Horizontal transgene spread | Yes | Key environmental risk |
| 4 | Poor seed quality | No | Quality preserved or enhanced |
Why It Matters for Students
For biology/biotech exams, focus on HGT as the top transgenic drawback due to its ecological implications. Mitigation includes buffer zones and monitoring.
