Herbicide-Tolerant GM Mustard: Why It May Not Fit Indian Farms
Analysis examines Dhara Mustard Hybrid-11 (DMH-11), a transgenic mustard hybrid developed by Delhi University researchers using genes from the soil bacterium Bacillus amyloliquefaciens, which remains pending field deployment nearly two decades after development began.
DMH-11 uses the barnase and barstar genes to enable hybrid seed production in mustard (normally a self-pollinating crop) and carries the bar gene, which additionally confers tolerance to glufosinate herbicide.
The commentary raises concerns that herbicide-tolerant mustard is poorly suited to India's small-holder, mixed-cropping farm systems, where non-crop plants growing alongside mustard serve nutritional, fodder and pollinator functions that herbicide use would eliminate.
It further flags risks of herbicide-resistant "superweeds," farmer dependence on privately supplied herbicides, and argues that India's roughly 56% edible oil import dependence is better addressed through agronomic measures such as the System of Mustard Intensification than through herbicide-tolerant biotechnology.
India's GM Crop Regulatory Framework: GEAC and the EPA, 1986
Genetically modified (transgenic) crops in India are regulated under the Environment (Protection) Act, 1986 and the Rules for Manufacture, Use, Import, Export and Storage of Hazardous Microorganisms/Genetically Engineered Organisms or Cells, 1989. The Genetic Engineering Appraisal Committee (GEAC), under the Ministry of Environment, Forest and Climate Change, is the apex biosafety regulator that approves environmental release of GM crops.
DMH-11's stalled field deployment despite 2022 regulatory clearance illustrates how India's GM approval pipeline, shaped by the Bt brinjal moratorium precedent, remains contested at both the regulatory and judicial level — directly relevant to the commentary's point that HT mustard "awaits field deployment."
Herbicide Tolerance vs Pest Resistance: Distinguishing GM Traits
GM crops are engineered for different traits with different risk profiles. Bt crops (like Bt cotton/Bt brinjal) confer pest resistance via an insecticidal protein; herbicide-tolerant (HT) crops instead allow a specific herbicide to be sprayed over the standing crop, killing weeds without harming the crop.
Key Details
- Bt trait: derived from Bacillus thuringiensis, produces a protein toxic to specific lepidopteran pests (e.g., bollworm in cotton, shoot-and-fruit borer in brinjal)
- HT trait: the bar gene (from Streptomyces hygroscopicus/Bacillus amyloliquefaciens constructs) confers tolerance to glufosinate ammonium herbicide, allowing post-emergence spraying
- HT crops are associated globally with monoculture, mechanised farming (e.g., US Midwest soybean/maize), a contrast the commentary explicitly draws with India's mixed-cropping smallholder systems
- Separately, non-transgenic HT mustard lines developed through induced mutagenesis (chemical/radiation mutation breeding) can bypass GEAC's biosafety review altogether — since March 2022, the Environment Ministry has exempted SDN-1 and SDN-2 genome-edited/non-transgenic plant products (which involve no insertion of foreign genetic material) from GEAC's Rules 7-11 scrutiny under the 1989 Rules, placing them closer to conventional mutation-bred varieties for regulatory purposes
The commentary's warning about circumventing GM classification refers to precisely this regulatory gap — herbicide tolerance achieved via mutation breeding (rather than transgenic insertion) can reach farmers' fields without the GEAC scrutiny that transgenic DMH-11 has undergone.
Edible Oil Self-Sufficiency and the National Mission on Edible Oils-Oilseeds
India's edible oil import dependence is the core economic driver behind mustard productivity efforts, including both HT breeding and the government's oilseed self-sufficiency mission.
The commentary's core counter-proposal — agronomic intensification (e.g., System of Mustard Intensification) over biotechnology — is framed as a more India-appropriate route to the same NMEO-Oilseeds self-sufficiency goal that HT mustard is meant to serve.
- DMH-11 genes: barnase + barstar (hybridisation) + bar (glufosinate tolerance), all from Bacillus amyloliquefaciens-derived constructs
- GEAC approved DMH-11 environmental release: October 2022; Supreme Court split verdict: 2024, referred to larger bench
- Bt cotton: India's only approved commercial GM crop (2002); Bt brinjal moratorium: February 2010, still in force
- Non-transgenic (SDN-1/SDN-2) genome-edited plants exempted from GEAC review: March 2022
- India's edible oil import dependence: ~56%; ~16 million tonnes imported in 2024-25 (~Rs 1.61 lakh crore)
- Mustard: ~45% of India's ~12 million tonnes domestic edible oil output; ~9 million hectares under cultivation; yield ~1.3-1.5 tonnes/hectare
- NMEO-Oilseeds (2024-25 to 2030-31): target of 69.7 million tonnes primary oilseed production by 2030-31, meeting ~72% of domestic edible oil demand