Gene-splicing opens new world for agriculture
To judge from recently announced "breakthroughs," gene-splicing may be the biggest boon for agriculture since people began breeding plants and livestock. But it will probably take many years for the encouraging trends now seen in the laboratory to have a major impact on the farm.
That seems to be the underlying message in reports of such developments as the so-called "sunbeam," a sunflower tissue culture to which was transferred a proten- coding gene from the French bean.
A significant advance in this research was announced in recent weeks by the US Department of Agriculture (USDA). Equally important work in this area also is being done elsewhere, especially in West Germany.
Such developments have sparked speculation about improving food crops -- giving grain plants the ability to make their own nitrogen fertilizer as legumes now do or boosting the protein content of corn. However, there are long and difficult steps to be taken before laboratory knowledge can be transformed into practical, commercial applications.
Ultimately, these applications are expected to be enormous. Last May, for example, the research firms Policy Research Corporation and The Chicago Group Inc. issued a study that estimated gene-splicing could eventually create a $50 billion to $100 billion annual global market for agriculture. But it is hard to forecast how fast that market will develop. Thomas T. Bamford, research chief for FMC Corporation, typifies the caution some experts feel when he says, "The hype has confused a lot of people into thinking the problems of working with plants are more tractable than they are."
The sunbean typifies one of the benefits experts now expect the new tools of genetic engineering to give farmers -- inserting foreign genes into plants or animals to give them new capabilities.
THe true genetic revolution in agriculture will come with inserting genes into crop plants, and eventually perhaps into animals also. This raises the prospect of cross breeding across natural reproductive barriers between species and genera and even between the plant and animal kingdoms.
One way to introduce the genes is to use a natural carrier. Last year, biologists at the Max Planck Institute in Cologne, West Germany, used the bacterium Agrobacterium tumefaciensm as the agent. This bacterium causes galls into plant cells, they were unable propagate whole plants carrying the new gene. This spring, Marc Van Montagu of the Free University of Brussells announced that his laboratory had circumvented the problem. It was able to produce new plants with the desired gene. What is more, he has deleted the bacterial genes causing abnormal growth.
On June 29, Secretary of Agriculture John R. Block announced similar work carried out by a USDA-University of Wisconsin research team under USDA biologist John Kemp. they have used A. tumefaciensm to insert a French bean protein gene into cells of the sunflower. This is the "sunbean." It really isn't bean at all , but a sunflower tissue culture. Unlike Van Montagu's cultures, these so far have not produced viable plants.
Nevertheless, the long-term potential is there to give plants new capabilities, although as Secretary Block noted, the payoff may not be until the next century. Also, it is unclear just how useful transferring one gene may be. Thomas N. Urban, president of Pioneer Hi-Bred International Inc., the biggest hybred seed corn producer, has pointed out that plant qualities usually depend on a complex of genes. "The new techniques will be helpful in speeding up our work . . . ," he says, "but they won't change conventional breeding methods." This was the conclusion also reached by the congressional Office of Technology Assessment in its report on biotechnology released in April. "The new tools will be used to complement, but not to replace, the well-established practices of plant and animal breeding," it said.
Another applications of gene-splicing now under study involves a bacteria-made vaccine for the animal malady called foot-and-mouth disease. In the vaccine work, researchers use Escherichia coli,m the bacterium most widely employed in gene-splicing studies. Hans Kupper and colleagues at the University of Heidelberg and the Max Planck Institute for Biochemistry in West Germany reported early this year that they had successfully given E. colim the gene that codes for one of the four proteins in the so-called "overcoat" in which the hoof and mouth disease virus is wrapped. The bacteria then were able to systhesize the protein.
On June 18, 1981, Secretary Block announced that a USDA team under Howard L. Bachrach had managed to give E. colim the gene for another of the viral proteins. These bacteria not only can make the protein but they make it in quantities 1, 000 times larger than the German microbes. Furthermore, this protein has been shown to be an effective vaccine whereas this had yet to be reported for the protein produced by Kupper's bacteria.
The USDA researchers worked with scientists of the biotechnology company Genentech, which holds patent rights on the vaccine production and the right to license its manufacture. It plans to make and sell the vaccine itself under agreement with International Minerals. With commercial production starting as early as the mid-1980s, this business could develop a $200 million-a-year international market, Genentech reportedly estimates.
This is only part of the potential market for bacteria- made farm chemicals. Last March, Genentech announced plans to make bovine growth hormone this way and to field-test it. This natural growth factor could speed up cattle growth and boost milk production, it is believed. another valuable chemical that might be made by specially engineered bacteria is rennin, the cheesemaking protein traditionally taken from calves. A decline in calf marketing has created a rennin shortage.
In essence, making these or other agrichemicals from genetically engineered bacteria is no different from making other chemicals this way. The big step now is to scale up successful bacterial production to commercial size. This involves tough challenges, such as ensureing the bacteria do not lose their newly gained talent. These are not expected to be a major problem. Speaking of this in connection with scale-up of its insulin process, Fred Lloyd, vice-president for production of Eli Lilly sys, "We are not having unusual problems in scaling up -- nothing we can't handle."