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Scientists from India genetically engineer DMH-11 species of mustard
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Wednesday, 01 November, 2017, 08 : 00 AM [IST]
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Ameya Harmalkar
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Genetic change or mutations are crucial for the survival and evolution of any species in order to acclimatise with the environmental changes. However, in today’s world, natural selection is not the only parameter that drives genetic change. From the selective breeding techniques used by Babylonians to the incorporation of dwarfing genes in the Green Revolution of the 1960s, mankind has reached a stage where artificial selection and hybridisation can be done on species to develop a genetically-modified hybrid species with certain specific elevated traits. The DMH-11, a genetically engineered species of mustard, is one such marvel that has been engineered by a group of Indian scientists.
Hybrids are species that are obtained by genetic crossing of two diverse plants from the same species. This is mainly done as the first generation offspring that results out of the hybridisation yields either higher yields than that of the individual plants or has some other specific properties. However, in self-pollinating species like mustards, no natural hybridisation can take place. This is because in self-pollinating plants, the flowers contain both the pistil and the stamen i.e., the male and female reproductive organs. The self-pollination is favoured to such an extent that the egg cells of one plant cannot be fertilised by the pollens from another plant of the same species and hence, the scope for hybridisation is restricted. Pental and his team have introduced a viable hybridisation system in mustard by genetically engineering the mustard crop. This was done by sterilising either one of the male or female parental lines. The immediate cause of this will be that the plant species will be forced to cross with other plant pollens to produce a hybridised seed. This was achieved by the introduction of barnase enzyme into the Indian variety Varuna bn3.6 to inhibit the male parental line.
Another bacterial gene namely barstar was introduced for the restoration of male fertility in the hybrids. It basically binds itself with the barnase protein to deactivate its RNAse activity. This basically restores the fertility of the F1 hybrids of DHM-11 plant. Additionally, the incorporation of specific genes like herbicide resistance to Glufosinate (Basta, Bayer’s herbicide analogous to Monsanto’s Glyphosate), TA29 for regulator, CaMV 35S, Cauliflower Mosaic Virus (as viral promoter), AMV, Alfa-Alfa Mosaic Virus (as viral promoter), and Agrobacterium tumefacians as Terminators was also done. The technology thus employed, utilised multiple gene transformations and introduction of genes from some particular (unrelated) organisms.
With genetically engineered mustard about to gain access to commercial markets, there are still debates going on on the ethical, economical and scientific issues that it needs to address. Even intriguing is the question put on the need of the GM mustard and its development for Indian fields. I would like to state the current scenario in this regard. As of the year 2015-2016, India imported around 15 million tonne of edible oil charging approximately $11billion to the Indian economy. With India’s edible oil growth production limited to 7.5 million tonne, of which mustard oil contributes roughly a quarter, the importance of increment in domestic crop yields is indubitable. Hybrid technology being potential to boost crop yields, the development of GM mustard crop is somewhat demanding. Pental and his team have claimed that the hybrid gives 25-30% more yield than the best varieties, currently Varuna, which is grown in the country. So, the issue of development of yield of crops has been tackled. The hybrid is said to be herbicide-tolerant and disease-resistant. Considering the population growth and the mammoth demand of our country, these points seemingly favour the use of GM mustard. However, this is just one side of the coin. The use of genetic engineering in edible food crops brings with it, a lot of parameters that must be tackled first.
The potential threats of the use of this technology are many and more or less, each threat is viable and must be considered before the market release of the crop. The hybrid proposed by Pental incorporates multiple gene insinuations from unrelated sources, so there is a crucial need to check the gene for all the specific components and there possible impacts on human beings. An assertion in the assessment that made me quite inquisitive was that it claimed its composition to be “similar” to that of the commercially cultivated mustard. However, the composition equivalency does not imply that expression of the specific genes will be equivalent. E.g., the rendered meat of cows that was fed to cows in the UK leading to the Mad Cow epidemic had “similar” composition to the commercial feed, however, it still lead to an epidemic! The barnase enzyme breaks down RNA discriminately and so it might be toxic to humans on consumption. The edible parts of the crop are the seeds and the leaves. According to the assessment that was done, barnase protein was found in detectable quantities only in the bud and was not detected anywhere else in the plant. The Barstar protein was found to be in small proportions in the buds. However, the Barnase, barstar and Barproteins have not been tested for safety on consumption and this might resort in being the most potent threat in commercialising the crop. Additionally, the viral promoters and terminators must also be tested for their expression.
The hybrid is stated to be herbicide-resistant. Now, adverse effect of this will lead to the growth of unstoppable super weeds due to overuse of herbicides on the crops. Mustard is not only a digestive plant, but also a medicinal species. The indulgence of genetic modification and excessive herbicide use will lead to the herb filled with herbicidal poison, and loss of a natural medicinal entity as a whole.
Naturally, the commercialisation of GM mustard will lead to the total replacement of our ‘desi’ indigenous mustard and this will lead to a loss of biodiversity. Moreover, in India, where scarcity of lands is a major issue, the crossing could occur between GM mustard and any other adjoining species. The trans-genes however, will contain genes of male sterility, viral promoters and herbicide tolerance, and thus genetic contamination of native crops by this hybrid is inevitable. The Assessment claims that pollen cannot travel more than 20 ft distance3, but the pollination studies of mustard clearly show that pollination by herbicide- resistant hybrid contaminated 67% farms up to 3 km. This shows the blatant inaccuracy in Pental’s calculation as the margin of error is almost 50000%.
With GM mustard being commercialised as an edible crop, it is of paramount importance to perform toxicological studies on the crop as a whole. The time of these studies and subsequent blood reports must also be considered. Also, the aroma content must be given a thorough check. The plant aromas in edible crops stimulate our bodily organs which play a vital role in human digestion. A thorough analysis of aroma and taste is hence a must! Along with these things, the socio-economic assessment holds a whole different angle. Like the monopoly which happened during the commercialisation of BT cotton, the seed costs which are high enough are a matter of concern. GM seeds are more expensive than the indigenous seeds, which could be a financial burden to the farmers who must purchase them every year. Additionally, the use of GMOs on fields has decreased the microbial community abundance thus compromising the fertility of the soil as a whole.
To conclude the pros and cons of the debate, I would like to state that the technology that has been employed for the production of genetically-modified organisms is astounding. However, the use of GM techniques on edible foods follows a huge set of ethical, natural and socio-economic factors that should be followed. As stated earlier, there are more threats than strengths of commercialising genetically engineered edible food crops. However, the use of genetic engineering to produce species like cotton, which are not edible but still load the economy in terms of imports, is worth trying. The use of this marvelous technology should be focussed more on the areas where we have absolutely no alternative. For example, the vaccine for Ebola in 2014 was manufactured by genetically-modified tobacco plants. The ‘pharming’ of genetically-modified tobacco plants was done, and post-harvesting, the cells are popped open and the drug is collected.
Similarly, a GM corn plant that produces Hepatitis B antigen has been harvested and turned into an oral vaccine tablet, as opposed to the current liquid formulation that requires refrigeration, injection and trained medical personnel. GMOs have a broad scope and application in these areas. As far as edible crops are concerned, natural cross breeding, selective rotation of crops and modified agricultural techniques can lead to a major increase in the yields without having to compromise the parameters of biodiversity, taste or the consumption quality of the crops.
Thus, technology for genetic modification /engineering of the crops has huge scope of progress in the future, however, instead of utilising the technology for large-scale commercialisation of edible crops which can endanger humans and the biodiversity as a whole, the efficient technology should be used on issues that are far more concerning, like the medications of several viral and bacterial pandemics and epidemics for nurturing and benefiting the entire mankind!
References
1. Arun Jagannath, N. Arumugam, Vibha Gupta, Akshay Pradhan, Pradeep Kumar Burma and Deepak Pental. Development of transgenic barstar lines and identification of a male sterile (barnase)/restorer (barstar) combination for heterosis breeding in Indian oilseed mustard (Brassica juncea).
2. Stewart, C. N., Halfhill, M. D. & Warwick, S. I. Genetic modification: Transgene introgression from genetically modified crops to their wild relatives. Nat. Rev. Genet. 4, 806–817 (2003).
3. Centre for Genetic Manipulation of Crops (CGMCP) , University of Delhi, South Campus. Assessment of Food and environmental safety (AFES) for Environmental release of Genetically Engineered Mustard (Brassica juncea) hybrid DMH-11 and use of parental events (Varuna bn3.6 and EH2 modbs2.99) for development of new generation hybrids.
4. The Big Picture: GM Mustard – Pros and cons. Insightsias
5. Prof. Gilles Eric Séralini, Chef Jerome Douzelet. GM Mustard in India? Five unanswered questions.
6. Holst-Jensen, A., Rønning, S. B., Løvseth, A. & Berdal, K. G. PCR technology for screening and quantification of genetically modified organisms (GMOs). Anal. Bioanal. Chem. 375, 985–993 (2003).
7. Eastham, K. & Sweet, J. Genetically modified organisms (GMOs): the significance of gene flow through pollen transfer: a review and interpretation of published literature and recent/current research from the ESF ‘Assessing the Impact of GM Plants’ (ASIGM) programme for the European Science Fountain and the European Environmental Agency / authors, Katie Eastham and Jeremy Sweet. (European Environment Agency, 2002).
8. Subramanian, T. S. R. Say no to GM mustard. The Hindu
9. Kuchroo, S. GM Mustard is ready. But are we?
10. Sarich, C. Genetically Modified Mustard? Biotech Makes more Questionable Claims.
(The author is student at the Institute of Chemical Technology, Mumbai. He can be contacted at harmalkar.ameya24@gmail.com)
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