Plant Biotechnology Can Quickly Offer Solutions To Hunger In Africa

Biotech now offers solutions to hunger in Africa. The idea is to literally "weed out" hunger by eradicating the parasitic weeds that infest field crops. We are talking about at least doubling crop yields while preventing environmental devastation. Yet large-scale implementation efforts lack the support of the biotech and chemical industries, which ignore the potential benefits -- and profits -- that would come from applying these new weed-fighting strategies. At the same time, potential biotech solutions are being ridiculed by extremists in the environmental movement who do not understand the positive impact self-sufficiency has on the environment. Since colonial times, agricultural yields in Africa have dropped drastically -- typically more than fourfold -- for two major, interrelated reasons. One is pretty-looking plants called witchweeds (Striga spp.) and their Mediterranean cousins called broomrapes (Orobanche spp.); and the other is government policies of keeping local agricultural prices artificially low. The witchweeds infest grain crops and legumes in sub-Saharan Africa, while the broomrapes attack vegetables, sunflowers, and the grain legumes that are the staple protein source throughout the Middle East. These parasites attach themselves to the roots of a host crop and send up a signal that says, "Feed me." They suck up not only the crop's energy but also much of the soil's nutrients. As a result, the crop withers while the parasites shoot up triumphant stalks crowned with flowers that spew out tens of thousands of seeds. Thus, there are two HIV problems in the Third World: one is the AIDS virus, and the other stands for "highly invasive vegetation," an acronym coined by P.C. Quimby of the United States Department of Agriculture Rangeland Weeds Laboratory in Bozeman, Mont. In fact, one type of HIV is related to the other, as the decreased crop yields cause the men to leave their wives and families in their native villages and look for work in the cities, where AIDS is rampant. Low yields facilitate disease epidemics by causing malnutrition, which exacerbates illnesses. There is all too often a tendency to say the major scourge of Africa is disease, while in fact its medical problems are inseparable from that of lack of food. The United Nations' Food and Agricultural Organization estimates that witchweeds alone cause more than 100 million farmers to lose half their already reduced yields (D.K. Berner et al., Plant Disease, 79:652-69, 1995). Couple that with government policies of keeping local agricultural prices artificially low, and you get a bleak picture of a yield-reducing spiral: farmers find it unprofitable to buy quality crop seeds, use fertilizers, or care about the quality of weeding. Agricultural biotechnology can offer the means to reverse that spiral. In one approach, Daniel Joel and his crew from the Newe-Ya'ar Research Center in Haifa, Israel, and I used seed (kindly provided or cajoled from DuPont Co. of Wilmington, Del.; Monsanto Co. of St. Louis; and Rhone-Poulenc Ag Co. in Research Triangle Park, N.C.) endowed with a different herbicide-resistance gene. We planted the seed and then sprayed seedlings with post-emergence herbicide. This technique killed the broomrapes without affecting the transgenic plants (D.M. Joel et al., Nature, 374:220-1, 1995). The genetic material we used allowed the herbicide to be transported unaltered through the crops' vascular system from the leaves into the roots, where it penetrated and killed the parasites. We are now trying to introduce such genes into local crop varieties as part of a joint Israel-Egypt-U.S. project sponsored by the Agency for International Development (AID). A different solution was necessary for the subsistence farmers of Africa who cannot afford even the small amount of herbicide and the spray equipment needed. Using biotechnologically engineered herbicide-resistant corn seeds and then soaking the seeds in those herbicides could provide a simple "quick fix." The parasites will unwittingly devour the weed-killing chemical from the roots or surrounding soil and die. By the time the crops ripen, the herbicide will be gone and will not affect the food supply. Joel K. Ransom, head of the International Center for Maize and Wheat Improvement office in Nairobi, along with George Odhiambo and Gordon Abayo of the Kenya Agricultural Research Institute (KARI) in Kisumu Station, Kenya, tested this technique in an area near Lake Victoria that is highly infested with witchweed. The tests were conducted with a special hybrid corn seed developed by Des Moines, Iowa-based Pioneer Hi-Bred International. This corn is biologically engineered for resistance to the imidazolinone group of herbicides. The Kenyans soaked the seeds with these herbicides and planted them in infested fields. The plants from the herbicide-treated seeds did well, while untreated neighboring plots were wasted away by parasitic weeds. Less than 0.5 mg herbicide per corn seed gave adequate weed control, tripling yields in the most heavily infested areas. This has been repeated for four seasons at two sites with consistent witchweed control. The results were presented last spring at an international symposium on parasitic weeds in Cordoba, Spain. In propounding the use of such small amounts of herbicides, we find ourselves caught between the "nozzle heads" and the "tree huggers," and vilified by both groups. The "nozzle heads," whose preferred solution to weed problems is to continually spray crops with herbicides, are not happy with our approach because treating the seeds cuts herbicide use about 20-fold compared with spraying the entire field. Moreover, it eliminates the need for costly spraying equipment. The main problem in getting our solution to farmers in Africa is that the chemical industry rarely views the Third World as a viable market. It fails to realize that subsistence farmers would and could pay $5 for the herbicide needed to treat the corn seeds required for planting a hectare field, since they would get $100 more worth of corn (J. Gressel et al., Annals of the New York Academy of Sciences, 792:140-53, 1996). Initially, credit would have to be supplied to cover the cost of the corn seed, which farmers traditionally save for use in following years. The added income would allow them to eventually afford to use fertilizers, which would double yields yet again. Such an upward spiral toward true self-sufficiency could lead farmers to growing hybrid crops and using yield-enhancing chemicals. Still, the chemical industry is reluctant to participate in such efforts despite the millions of hectares of potential market for its product. This position seems a disservice not only to humanity, but also to company shareholders. The "tree huggers," on the other hand, equate all chemicals and biotechnology with evil and oppose the herbicide resistance approach, even when it does not involve transgenic crops, as in the case of the corn in Kenya, which came from biotechnologically selected mutations in tissue culture. The ultra-greens have called for a moratorium on supplying such technologies to underdeveloped countries (R. Goldburg et al., Biotechnology's Bitter Harvest, New York, Environmental Defense Fund, 1990). The present "green" solution is to pull weeds out by hand. However, once the parasitic weeds appear above ground, it is too late; they have already drained the crop. Having lost the battle to the weeds, the farmers move on, sometimes encroaching on witchweed-free virgin lands in nature reserves. Governments allow such moves because the rhinos and hippos on the reserves do not vote, and their citizens are starving. Basically, the tree-huggers are saying, "Starve until a solution to the witchweed problem acceptable to us is found." I perceive this approach as being downright amoral. Another solution available to farmers is for the men to find work in the city, while the women are left behind to work the land. The "greens" distort this issue by arguing that the herbicide-resistance approach will create unemployment among women, who often spend up to 80 percent of their working hours pulling weeds. No work is more back-breaking and degrading than hand-pulling or hoeing weeds. I can only quote a Kenyan scientist, Florence Wambugu, who got up during an American Association for the Advancement of Science debate on this topic in Boston in February 1994 and said that her mother had spent a lifetime weeding, and that this was what she herself had done until the age of 15. She stated that a "woman's place is in a lab engineering herbicide-resistant crops so that other women don't have to pull weeds." The weed problem calls for an economical solution, and this is precisely what biotechnology combined with a judicious use of chemicals can offer. We cannot directly change the politics and economics of Africa, but we do have a way of dealing with its parasitic weeds. True, biotechnology may provide only a stop-gap solution; the weeds could indeed evolve resistance to the herbicide within several years. But it gives us a breather to find better approaches. My own laboratory is studying microorganisms that control broomrape, while other labs in Israel are trying to endow crops with genes that confer resistance to prevent weed attachment without the use of chemicals. Lee Segel, a Weizmann Institute mathematician, is helping to create mathematical models of herbicide resistance to see how it can best be delayed. The models predict that five stalks of resistant witchweed would appear on a one-hectare subsistence farm in the first year the biotechnology method is used, owing to a high mutation rate of the gene (J. Gressel et al., International Journal of Pest Management, 42:113-29, 1996). This would cause the weeds to spread over 10 percent of the fields in eight years. If the farmers walk their fields and remove all but one resistant stalk before they set seed, this spread would take more than 20 years. Meanwhile, Monsanto has developed genetically engineered corn with a gene coding for a modified EPSP-synthase, the enzyme targeted by a leading herbicide. The gene confers resistance to this herbicide, which is far less likely to lead to herbicide-resistant weeds than the one we are using is. The most difficult part of the biotechnology solution -- the isolation of genes that confer herbicide resistance -- has already been accomplished by industry. The public sector is willing to transfer this solution to African countries, with the hope that the biotech industry will at least provide the genes, and the chemical industry will finish the technological development and register and sell their herbicides in these markets. Governmental and private organizations, along with academic institutions such as my own, can all play an important role in this endeavor. It seems to me that, having a solution to hunger at hand, our society has a moral obligation to see it implemented. Jonathan Gressel holds the Gilbert de Botton chair of plant sciences at the Weizmann Institute of Science in Rehovot, Israel. His research on parasitic weeds is supported by grant HNE-0158-G-00-3060-00 of the trilateral USA-Egypt-Israel program of the U.S. Agency for International Development.

Plant Biotechnology Can Quickly Offer Solutions To Hunger In Africa

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