OPINION: WE CAN PREVENT FRIGHTENING SEQUEL TO POTATO BLIGHT Feb. 25 2000 Knight-Ridder Tribune CHURCHVILLE, Va. -- Dennis T. Avery of the Hudson Institute writes that Ireland is still dotted with roofless, stone-walled "famine cottages," abandoned since the 1840s, a time when 1 million Irish starved and another 1.5 million fled overseas. The people had to either flee or starve because the crucial potato crop had failed. They were victims of the world's most vicious crop diseaseQpotato late blight. Avery says the blight was stopped in the 19th century when farmers found and planted blight-resistant varieties of potatoes and gave them the additional protection of chemical fungicides. In recent years, unfortunately, more aggressive strains of potato late blight have spread around the world. The Irish blight did not reproduce sexually. Today's late blight strains do, so they spread faster. By comparison, the blight strain that struck Ireland in the 1840s was only a pale, half-hearted shadow of the current threat. Potato growers on five continents have been reeling under the blights' onslaught, and many Third World countries are almost as heavily dependent on potatoes as the Irish in the 1840s. Avery says that no crop produces as much food per acre as potatoes. That's a big reason why world potato production has soared to nearly 300 million tons a year, with about 40 percent grown in the densely populated countries of the Third World. Today, Asia and Africa are potato cultures, which makes the new strains of late blight a serious threat to the food security of millions of people. It has already cut potato production in poor countries by 15 percent and threatens to inflict even worse damage. Because of explosive growth, a field of blight-stricken potatoes can turn from flourishing health to horrifying rot seemingly overnight. The plant leaves turn black and wither. Many of the potatoes look healthy, but turn into an oozing mess within a day or two of harvest. First World farmers' best chemical weapon against the blight has been a fungicide named metalaxyl, but some Mexican farmers have to spray every three days to save their crops. This means the chemicals cost more than the potatoes will bring at the market. The International Potato Center now believes its researchers have harvested the first crops of commercially viable potatoes carrying deep-seated resistance to all the strains of potato late blight. These potatoes were bred by a method called recurrent selection, in which researchers crossbreed dozens of different potato clones and then recross their most promising offspring. Repeated several times, this recurrent selection allows the potatoes to accumulate many "minor" resistance factors. Center scientists believe that a major gene carried the original resistance to late blight. Its narrow, one-gene base was eventually surrounded and overwhelmed by hordes of constantly mutating blight fungi. Researchers believe that it will be much more difficult for the fungi to overcome the new, multiple-resistance varieties. Center director Wanda Collins was cited as noting that while observing potato fields all around the test sites shrivel and die, the breeders watched the new breed grow even in "warm, wet El Nino conditions conducive to late blight." Three sets of blight-resistant potatoes are being bred at two separate center sites in Peru, producing European-style potatoes for Africa and the First World; yellow-fleshed potatoes for parts of South America; and tropical potatoes produced by crossing the white and yellow varieties. Potato farmers will need to combine the resistant potatoes with integrated pest management, including the elimination of all possible places where the blight can survive between growing seasons. That means digging up any potentially infected tubers missed at harvest and destroying all vines.

`INDIA CAN'T AFFORD TO IGNORE BIO-TECHNOLOGY' Feb. 18 2000 Hindu Business Line Harish Damodaran NEW DELHI (Japanese{)-- 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, according to this story, 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.

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