Tampering with Beans and Genes

By Claudia Wallis

A harvest of cash and corn beckons microbiology and business

"We've got to learn to produce as much food in the next 40 years as we have in the past 11,000." So says Corn Geneticist Ronald Phillips of the University of Minnesota. Can it be done, especially since the so-called Green Revolution has just about run out of steam? The answer may lie in the fact that a second Green Revolution, powered by the wonders of genetic engineering, has been gathering impetus for some time and now seems within reach.

The seeds of the first revolution--high-yield, fertilizer-hungry super-grains--were sown all over the world in the 1960s. Bread-bare countries like Mexico and Iran were soon exporting wheat, the Philippines became self-sufficient in rice, even Pakistan had a harvest surplus. But soaring oil prices pushed the cost of essential petrochemical fertilizers out of reach of all but the wealthiest countries. Today nearly every country "revolutionized" by the Green Revolution is importing food from the world's half-dozen grain exporters, most notably the U.S.

Yet even the U.S. faces severe problems. Exotic new bugs proliferate. From Texas to Nebraska, water is in short supply and growing shorter. With 400 million acres of farm land, the nation is losing 3 million acres a year to erosion and urban development. Meanwhile, world population keeps rising, and is likely to double to 8 billion by the year 2020.

Though traditional plant breeding techniques have done wonders in the past, they are simply not working fast enough. Advanced genetic engineering and tissue-culture techniques may be the only hope. Molecular biologists and giant corporations are at last turning their attention, long concentrated on medicine and drugs, to plants. By manipulating the genetic makeup of plant cells and regenerating those cells in test tubes and Petri dishes, scientists will soon be creating plants with characteristics that might have taken a decade to develop by traditional crossbreeding techniques. The possibilities for farmers, scientists and some financiers are breathtaking: crops that manufacture their own fertilizers; plants that exude toxins to drive off pests; grains that grow in salty soils and others that can live for weeks without water.

According to James Murray of Chicago's Policy Research Corp., "there'll be a $50 billion to $100 billion annual market for agribusiness applications of genetic engineering by 1996--ten times the potential of medical-pharmaceutical applications." Within the past ten years, giant companies like Atlantic Richfield, Pfizer, Shell, Upjohn, Ciba-Geigy and Occidental Petroleum have bought seed companies, the obvious distributors of the products of agrigenetics.

Commercial labs, more than 50 so far, have sprung up across the country, creating a demand that allows top-flight researchers and agricultural scientists "to write their own ticket." In California venture capitalists have provided "seed" money for Calgene in Davis and Phytogene in Pasadena. In St. Louis Monsanto has just added a gleaming molecular biology center to its agricultural research facilities. Pioneer Hi-Bred International, the nation's top breeder of seed corn, has broken ground for its own high-tech molecular biology lab in Des Moines.

Inside these shiny new facilities, work is under way on the plants of the future. Last May a major breakthrough was achieved by Timothy Hall, advanced research director of the brand-new Agrigenetics Corp., and U.S. Department of Agriculture Biochemist John Kemp. The two succeeded in transferring genetic material from a French green bean plant into the cells of sunflower seedlings. It was the first time a gene from one plant had been successfully inserted into the chromosome of another, totally unrelated, species and made to express itself. Kemp and Hall christened their glowing achievement the "sunbean."

The potential utility of other recent experiments is even more striking. The high cost of nitrogen fertilizers, for example, is an overwhelming problem for farmers all over the world; the U.S. alone spends $2.5 billion a year on such chemicals. So researchers are focusing their efforts on creating plants that can "fix" their own nitrogen, that is, take nitrogen from the air and convert it into ammonia, which plants can use. Soybeans and other legumes already possess this capability, thanks to their symbiotic relationship with the nitrogen-fixing (NIF) Rhizobium bacteria that live in nodules on their roots. Much research is therefore aimed at enhancing the NIF capabilities of leguminous plants, or transferring the genes associated with this function to plants that do not have it.

By developing mutant strains of Rhizobium with superior NIF ability and inoculating soybeans with them, Wisconsin Bacteriologist Winston Brill has produced plants 50% larger than the average soybean. In field tests, though, these supermutants have so far failed to flourish. Brill, who is now head of the Madison lab of gene-splicing pioneer Cetus, has also crossed domestic corn with several rare tropical strains that produced root material capable of supporting nitrogen-fixing bacteria.

Because nitrogen fixation is a complex process governed by at least 17 genes, many agrogeneticists believe their first practical breakthroughs will come in other areas. Indeed, most of the early achievements will involve a mix of more traditional plant husbandry and sophisticated tissue-culture techniques. Among the most promising so far:

PotatoTest. At the USDA research center in Beltsville, Md., gene-splicing magic has created an easy test for the potato spindle tuber viroid, a minuscule squiggle of nucleic acid that annihilates potato crops in tropical climates. The test, which employs radioactively tagged clones, will allow breeders to identify and destroy infected seed potatoes.

Sea Tomato. At the University of California at Davis, researchers recently cloned microbes with a gene for salinity tolerance. Meanwhile another Davis team has produced a tomato that can be grown in sea water. It is cherry-size and tastes fine, say its inventors.

Dry Corn. At Illinois-based DeKalb AgResearch, old-fashioned crossbreeding has produced a remarkably hard new corn hybrid. Tested in the desert heat of Yuma, Colo., the Mexican-derived maize can survive for three weeks without water. Protein Rice. USDA researchers in Beltsville have used complex biochemistry on tissue cultures to create rice plants with 6% to 10% more protein than the usual variety, potentially a nutritional bonanza for the roughly 50% of the world's population that bases its diet on rice.

"Totatoes" or "Pomatoes." In Manhattan, Kans., Advanced Genetics Science Ltd. is concentrating on creating new plant species by cell fusion and regeneration. One brand-new result: a cross between the potato and the tomato. The aim was to breed a potato that would have a tomato's resistance to so-called late blight. So far the first plant to result is only six inches high, with a stalk like a potato but lobed leaves like a tomato. Researchers think it will probably grow tubers, but there is no sign of them yet.

Despite these advances, understanding of plant physiology still lags far behind research into animals and bacteria, partly because the genetics of higher plants is in some ways more complicated even than that of humans.

Some plants have more than twice as much DNA (deoxyribonucleic acid, known as the master molecule of heredity) as humans. Others have multiple pairs of chromosomes. This makes identifying plant genes, let alone tinkering with them, especially difficult.

Moving DNA around from one plant to another is a big problem. The viruses and plasmids used as gene "taxis" or vectors in bacterial research will not work in plants.

To make the sunbean, bean genes were carried to the sunflower DNA by a genetically altered gall-producing microbe.

But in the process the sunflowers themselves were covered with small, brown tumors and their cells became too ill to grow into full-size plants. No wonder geneticists all over the country are searching for better vectors.

Even when all the technical hitches are ironed out, geneticists still have to depend on nature to supply the raw material for their designs. For his work with nitrogen fixation, Bacteriologist Brill sent all over the world for Rhizobium samples.

Many plant scientists are deeply concerned about the threat to this genetic raw material--or germ plasm--posed by the slash-and-burn clearing of the world's tropical rain forests. In these remote regions, life forms compete so fiercely that unusual survival mechanisms and defenses often evolve.

High atop a Mexican mountain called Cerro de San Miguel, for instance, scientists have found a highly useful, living relic of Aztec agriculture. Called Teosinte (Aztec for grain of the gods), it is, according to University of Wisconsin Botanist Hugh Iltis, "an ancestor of the ancestor of corn." In two years of research, this stalwart survivor has shown great promise as a genetic source of pest resistance. "This is gold," says Iltis, who is passionate about preserving wild species. "All sorts of Teosinte are out there to be discovered, all sorts of potatoes and other food plants."

To the pioneers of the second Green Revolution, they offer genetic treasure--providing, of course, that they are found in time. --By Claudia Wallis. Reported by J. Madeleine Nash/Chicago and Dick Thompson/San Francisco

With reporting by J. Madeleine Nash/Chicago, Dick Thompson/San Francisco

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