Financial Daily from THE HINDU group of publications
Friday, Nov 08, 2002
Agri-Biz & Commodities
Bio-tech & Genetics
Why is Proagro's product controversial?
NEW DELHI, Nov. 7
WHAT is it that makes clearance for commercial cultivation of Proagro Seed Company Ltd's genetically modified (GM) mustard hybrids a tricky affair compared to the Monsanto-Mahyco combine's Bollgard (Bt) cotton?
The reasons are two-fold. Firstly, the Bt cotton transgenics concern a fibre crop, which is not used for direct human consumption. The so-called health and bio-safety implications of planting these genetically engineered cotton hybrids are, therefore, not so obvious.
This is not so with mustard, a food crop (oilseed) that meets a significant part of the country's vegetable oil requirement. Besides, unlike in the West, the consumption of mustard in India extends to virtually the entire plant, including using the leaf for making `sarson-ka-saag'.
Secondly, the level of genetic engineering in Proagro's mustard hybrids is much more complex relative to that of Bollgard cotton. The latter has essentially involved incorporating a foreign gene (Cry1Ac) isolated from Bacillus thuringiensis (Bt) a naturally occurring soil bacteria into Mahyco's already existing cotton hybrids. Given the Bt gene's property to synthesise proteins toxic to the dreaded bollworm pest, the resultant transgenics are said to possess `in-built' resistance towards these insects, obviating the need for spraying persticides.
But in the case of Proagro's GM mustard, there is not one, but three foreign (trans) genes involved. While `in-built' pest resistance is claimed to be Bt cotton's selling point, what makes Proagro's transgenic mustard hybrids unique is the very fact of they being hybrids in the first place.
To get a better picture, it may be noted that unlike maize, bajra, cotton, sunflower, castor, rice and a host of vegetables, there are no commercial hybrids for mustard in the country now. The reason is simple: mustard is a self-pollinating crop and there is no hybridisation system existing in nature for developing commercially viable hybrids. What Proagro has done is to `genetically engineer' such a hybridisation system for mustard.
Hybridisation involves crossing two genetically dissimilar plant varieties (though of the same species) and exploiting the `heterosis' or hybrid vigour often seen in the first-generation (F1) progeny.
This, in turn, requires the presence of suitable `cytoplasmic male sterile' (CMS) or `restorer' parental lines.
Hybrid seed breeding techniques rely on identifying or developing CMS parental lines (in which the male organs, i.e stamen, are sterile) and crossing these with a `restorer' line (which is male-fertile), so that the former can be pollinated by only the other parental line. The resultant progeny is a commercial F1 hybrid, having yields superior to either parents.
But since in mustard, there is no natural CMS-restorer system, the F1 hybrids exhibit floral abnormality and neither are they 100 per cent fertile. It is this lacunae that Proagro has sought to address through its `barnase-barstar' genetic engineering technology, a proprietary know-how of its German parent, Bayer CropScience.
There are three trans genes involved in this process. The first relates to introduction (using recombitant-DNA techniques) of a CMS `barnase' gene in a suitable traditionally-bred mustard variety, so as to impart complete male sterility and facilitate its use as a female parent. The second gene (`barstar') is a `restorer' incorporated in the male parent that restores complete fertility in the F1 hybrid. Both the `barnase' and `barstar' genes have been derived from a bacteria, Bacillus amyloliquefaciens.
But it is the third `bar' gene that has generated maximum controversy. This particular bacterial gene synthesises an enzyme phosphinothricin acetyl transferace (PAT) that confers `tolerance' to glufosinate, which is a patented herbicide molecule of Bayer. Glufosinate (marketed worldwide as `Liberty Link' and `Basta') is a broad-spectrum herbicide, similar to Monsanto's `Round-up' (glyphosate), which indiscriminately eliminates weeds and, indeed, any plant that does not incorporate the PAT (bar) gene and is hence not `herbicide tolerant'.
Critics allege that Proagro's main purpose of developing the GM hybrids is to promote the conjunctive use of Liberty Link and, thereby derive revenues from sale of seed as well as herbicide. Company officials, however, deny this, saying that the `bar' gene has been employed only as a `marker' for tracking the presence or absence of the `barnase' and `barstar' genes, ``which are the genes of interest''. Moreover, they add that glufosinate is not a registered insecticide in India and ``we do not see it being used here, given its exorbitant cost to the farmer''.
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