GM Crops

Genetically Modified Crops are plants whose DNA has been altered using genetic engineering techniques, typically by inserting a gene from a different species (transgenic) to introduce a specific trait. This process bypasses traditional breeding limitations and allows for the precise introduction of desirable characteristics.

Key Mechanisms in GM Technology

Recombinant DNA (rDNA) Technology

The process involves identifying a gene with a desired trait (e.g., pest resistance), isolating it, and inserting it into the genome of a host plant using a vector.

Common Vectors

• Agrobacterium tumefaciens: A soil bacterium naturally capable of transferring DNA to plants; often called “Nature’s Genetic Engineer.”
• Gene Gun (Biolistics): A physical method where micro-particles of gold or tungsten coated with DNA are “fired” into plant cells.

Major Targeted Traits

• Herbicide Tolerance (HT): Allows plants to survive specific broad-spectrum herbicides (e.g., Glyphosate).
• Insect Resistance: Plants produce their own insecticidal proteins.
• Biofortification: Increasing the nutritional value (e.g., Vitamin A in Golden Rice).
• Abiotic Stress Tolerance: Resistance to drought, salinity, or extreme temperatures.

Prominent GM Crops and Applications

Bt Cotton (Only Commercialized GM Crop in India)

• Mechanism: Contains genes (Cry1Ac and Cry2Ab) from the soil bacterium Bacillus thuringiensis.
• Target: Effective against the Bollworm complex.
• Function: The Bt gene produces a pro-toxin that becomes active in the alkaline pH of the insect’s gut, creating pores and leading to death.

GM Mustard (DMH-11)

• Developer: Centre for Genetic Manipulation of Crop Plants (CGMCP), Delhi University.
• Technology: Uses the Barnase/Barstar system for hybrid seed production.
  • Barnase: Induces male sterility.
  • Barstar: Restores fertility in the hybrid.
• Significance: Aims to increase yields and reduce India’s edible oil import bill.

Golden Rice

• Trait: Biofortification.
• Technology: Inserted genes from Daffodil and a bacterium (Erwinia) to produce Beta-carotene (Pro-vitamin A) in the endosperm.
• Goal: To combat Vitamin A Deficiency (VAD), which causes night blindness.

Bt Brinjal

• Status: Developed in India by Mahyco; however, it is currently under an indefinite moratorium (since 2010) due to biosafety concerns, though it is commercially grown in Bangladesh.

Regulatory Framework in India

Environmental and Biological Concerns

• Gene Flow (Superweeds): The risk of the transgene escaping to wild relatives through cross-pollination, potentially creating herbicide-resistant weeds.
• Impact on Non-Target Organisms: Concerns that insecticidal proteins might harm beneficial insects like honeybees or butterflies.
• Antibiotic Resistance Markers: Use of antibiotic-resistant genes during the selection process in the lab could theoretically transfer to gut bacteria.
• Monopoly: Domination of the seed market by a few multinational corporations (e.g., IPR and seed patenting issues).

UPSC Prelims: Essential Facts and Trivia

• Transgenic vs. Cisgenic: Transgenic involves genes from a different species; Cisgenic involves genes from the same or a closely related species that could otherwise be bred naturally.
• RNA Interference (RNAi): A newer GM technique that “silences” specific genes without necessarily adding foreign DNA (used in Flavr Savr tomatoes to delay ripening).
• HTBT Cotton: Refers to Herbicide Tolerant Bt Cotton. While Bt cotton is legal in India, the HT trait is not yet officially approved for commercial cultivation, though illegal cultivation has been reported.
• Cartagena Protocol: An international agreement under the CBD (Convention on Biological Diversity) that governs the movement of Living Modified Organisms (LMOs) from one country to another to ensure biosafety.
• The “Bar” Gene: In GM Mustard, the ‘Bar’ gene provides tolerance to the herbicide Glufosinate, which is used primarily as a marker for selecting successful hybrids during the breeding process.