Tilak Raj Sharma writes: On GM, follow the science

The recent approval for the environmental release of Genetically Modified (GM) hybrid mustard DMH 11 and its parental lines has attracted the attention of the public. There has been some criticism of the move, including in this newspaper (‘Stay with Science, go slow on GM’, December 22).

All the national agencies concerned with the areas of agricultural research, health, biodiversity and ecology were involved in the risk assessment of the product before it was considered safe. Questioning the credentials of scientists at the Indian Council of Agricultural Research (ICAR), Indian Council of Medical Research (ICMR), Department of Biotechnology and other regulatory bodies is a cynical, if not dangerous, approach.

GM is a disruptive technology because it can bring about targeted changes in crop varieties that cannot be achieved through normal breeding of plant lines. The crops bred through this technique have to, of course, be safe for humans, animals and the environment. In the case of DMH-11, the objective of genetic modification was to make the mustard crop amenable to hybridisation.

Why hybrids? Hybrid plants that result from the crossing of genetically diverse parents generally demonstrate higher yields and wider adaptation. This is a phenomenon known as heterosis or hybrid vigour, which has been widely exploited in crops such as maize, pearl millet, rice, sunflower and many vegetables. Hybrids typically show 20-25 per cent yield increases over conventional-bred varieties across crops.

Hybrid technology can play an important role in boosting yields of rapeseed-mustard, which is India’s major oilseed crop. Our current mustard yield, at 1.2-1.3 tonnes per hectare, is roughly half of the global average. We need to raise this not just for mustard, but all oilseed crops. In 2021-22, India spent Rs 1,56,800 crore on the import of 14.1 mt of edible oils, equivalent to nearly a third of our total domestic consumption. Those who question the necessity of GM mustard cultivation should answer a simple question: Isn’t the current forex drain on imports of edible oil a “compelling” reason? The doubters would have probably said the same thing in the Sixties when India was leading a ship-to-mouth existence in foodgrains. We trusted the wisdom of our scientists and that brought us the Green Revolution.

This leads to the next question: Why GM hybrids? Hybrid seed production requires an efficient male-sterility and fertility-restoration system – so that one of the parent lines can be crossed with the pollen from only the other parent, even as the resultant plant is fertile. The existing mustard hybrids have limitations of sterility breakdown under certain environmental conditions, resulting in lower seed purity. So much so that in 2014 the agriculture ministry relaxed the usual purity standard of hybrid seeds in rapeseed-mustard to 85 per cent, from 95 per cent under the SeeAbu Dhabids Act 1966.

The GM “Barnase-Barstar” system provides an alternative route for hybridisation in mustard that is robust and addresses the sterility breakdown problems. This technology has been successfully deployed in other countries.

DMH-11 has been developed by scientists at Delhi University’s Centre for Genetic Manipulation of Crop Plants. They have used the “barnase-barstar” system with some improvements to breed the hybrid. This has undergone all the required regulatory testing processes. DMH-11 was tested in confined field trials at multiple locations. It showed around 28 per cent higher yield over the national best “check” mustard variety Varuna, besides being subjected to all the biosafety tests required under the officially stipulated guidelines and rules. It was based on all these scientifically-conducted assessments that the Genetic Engineering Appraisal Committee (GEAC) recommended the environmental release of DMH-11 and its parental lines.

It is nobody’s case that DMH-11 per se will solve India’s edible oil imports problem. The environmental release of its parental lines will help mustard breeders to deploy the robust and versatile “Barnase-Barstar” system to develop newer-generation mustard hybrids with greater yield and other superior trait advantages. This will be a significant step forward in addressing the problem of low productivity in mustard, helping bring down imports of edible oil in the future.

The doubters have questioned the safety of the three genes – Barnase, Barstar and Bar – used to develop GM mustard. Extensive studies on toxicity, allergenicity, compositional analysis, field trials, and environmental safety studies of GM mustard lines vis-à-vis their non-transgenic comparators have established their safety.

The final allegation levelled against DMH-11 is that it will promote use of herbicides. The Bar gene does confer resistance to the herbicide glufosinate. But the gene has been used, firstly, as a selectable marker in tissue culture during the breeding process. Secondly, the herbicide-tolerance trait in both the Barnase female and Barstar male lines is to be exploited only for production of hybrid seed and not in the commercial cultivation of hybrids. The GEAC has also approved herbicide use only for hybrid seed production. It must be noted here that approximately 15,000 tonnes of herbicide (technical material) worth Rs 7,000 crore is already being applied annually by Indian farmers in rice, wheat, soyabean and other crops even without any genetic modification. So, what is new in the use of a herbicide for seed production?

GM crops are today grown in over 30 countries. Adoption rates of GM traits have been more than 95 per cent in some cases with no evidence of adverse effects. If India is at present importing GM canola oil, why can’t its farmers cultivate mustard by deploying the same technology?

The ICAR and other publicly-funded institutions have been working on breeding GM crops for different traits such as higher yields, biotic and abiotic stress tolerance. It is in the welfare interests of farmers and consumers that a positive environment is created in the minds of our agricultural scientists to conduct research in biotech crop development. The landmark decision of the government to approve GM mustard should be taken to its logical conclusion.

The writer is Deputy Director General (Crop Science), ICAR

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