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India Can't Afford to Ignore Bio-technology

Hindu Business Line
February 18, 2000
By Harish Damodaran

For someone who is part of the US Agriculture Secretary, Mr. Dan Glickman's official think-tank on plant bio-technology and has deposed before Congressional committees on genetically modified crops, Dr. Channapatna S. Prakash comes across as a remarkably affable and down-to-earth person.

The 42-year-old Director of the Centre for Plant Biotechnology Research at Tuskegee University in Alabama - founded by the legendary Afro-American agricultural chemist and botanist, Dr. George Washington Carver - has many 'firsts' to his credit, including the breeding of transgenic sweet potato plants, identification of DNA 'polymorphism' (occurrence of the same substance in different forms) in peanut and the development of a genetic map of cultivated peanut.

But along with his considerable research accomplishments in transgenic crops, gene expression and plant genomics, Dr. Prakash also exudes a refreshingly evangelical disposition, when he calls for promoting the 'responsible use' of bio-technology in enabling developing countries to feed their expanding populations in the face of limited land and water resources and growing environmental stress constraints.

The 'Gene Revolution', he contends, is far more environment-friendly compared to its predecessor 'Green Revolution'. The latter requires breeders to make wild crosses of crops with their weedy relatives that are known to harbour desired genetic traits. Most of the rust-resistant high-yielding wheat varieties developed today, for instance, incorporate one or more of the 47-odd identified leaf rust resistance genes, many of which are derived from related alien species.

The flip side of the conventional breeding strategy, Dr. Prakash notes, is that "you also end up introducing large chunks of chromosomes with undesirable genes, about whose traits we may even have little knowledge". As a result, breeders have to continue to make further crosses and selections until they evolve a 'pure line' incorporating only the particular desired attribute and eliminate all the unwanted genes.

"It is a tedious, hit-and-miss process, which may sometimes not even yield any results. Sometimes, it could take up to 20 years to develop a variety ripe for commercial release," he points out, while referring to the efforts of Dr. G.S. Khush of the Manila-based International Rice Research Institute (IRRI) in the 1970s to cross the well-known IR-24 rice with a wild related species, Oriza glaborima, in order to transfer the latter's bacterial blight resistance traits.

The efforts did not bear fruit because although the derived progeny did incorporate bacterial blight resistance, "they also developed several weedy traits due to other genes tagging along". The problem could be solved eventually only through modern bio-technology and recombinant DNA techniques, which allows one to focus on particular genes in plants, rather than the entire plant, and to identify and transfer the specific gene coding for the desired trait.

"That was precisely what Dr. Swapan Datta from the same IRRI did. He managed to isolate and clone the particular bacterial blight resistant 'Xa21' gene from Oriza glaborima and inject just this into the existing high-yielding rice varieties," Dr. Prakash says. The relative environment-friendliness of 'genetically reprogrammed' crops over conventionally bred or even naturally evolved varieties springs essentially from their not involving any wholesale introduction of thousands of new genes through new plants, but merely "alteration of just one or two genes with known traits in the already popular crop varieties".

Dr. Prakash points out that the problems of 'monocropping' conferred by the Green Revolution are also basically rooted in the labour involved in breeding thousands of plants to obtain a single desired trait. "As this selective breeding route affords little flexibility, once an improved variety of, say rice is evolved, there is a tendency to plant it across the entire country. With genetic re-programming, the time span for developing new varieties can be reduced to 3-5 years and hence more varieties can be released in every region with precise modifications," he claims.

Moreover, through advanced bio-technological techniques such as gene shuffling, it is possible to isolate the gene of any plant variety and 'shuffle' its DNA material around. "Molecular biology techniques such as the use of DNA markers and genomics provide valuable insights into the dynamics of biodiversity in crop plants and thus help us understand crop evolution and perhaps also recreate extinct crop traits. This permits more intelligent use of available biodiversity," he observes.

Dr. Prakash feels that India can ignore bio-technology 'only at its own peril', considering that developing countries including Mexico, Argentina, China and Chile have already made significant strides in integrating bio-technology into their agricultural programmes, with others such as Cuba, Egypt and South Africa closely following suit.

"Indian farmers encounter serious disease problems of blast in rice, rust in wheat, leaf rust in coffee, viruses in tomatoes and chillies and leaf-spot in groundnut, besides pests such as shoot borers in brinjal and bollworm in cotton. Conventional plant breeding or use of chemicals have little ammunition to deal with these in an expedient and efficient manner. Cotton farmers alone spend a staggering Rs. 1,600 crores annually on pesticides to combat the American bollworm menace, with diminishing results," he points out.

These problems can be significantly minimised by using genetically re-programmed seeds designed to resist disease attacks, while economising on the use of costly and harmful pesticide sprays. According to Dr. Prakash, the Gene Revolution is potentially more scale neutral and small farmer-friendly than the Green Revolution, as its potency revolves entirely around genetically re-programmed seeds and there is less dependence on the conventional package of inputs, especially pesticides and other costly chemicals.

Further, bio-technology can also help address the dilemma posed by the presence of hazardous substances in several Indian foods - neurotoxin in kesar dal, cyanide in tapioca, aflatoxins in groundnut and anti-metabolites in chickpea, horsegram and sweet potato. This essentially entails introducing the genes responsible for the said undesirable traits in the concerned crops and derived from the same plant, but inserting it in a reverse manner to 'silence' its functioning, Dr. Prakash added.