A NUMBER of gene-tailored crop plants are getting ready to enter full-scale commercial use. Products such as tastier, longer lasting tomatoes or blight-resistant vegetables could benefit consumers and farmers alike. Yet some recently reported research suggests the regulators and genetic engineers should continue to proceed with caution.
Take the trick that makes a crop plant resistant to a virus by putting a piece of the virus's genome into the plant's own genetic code. Crop scientists consider this a promising way to protect plants without using pesticides, even though they don't know why it works. Now studies at Michigan State University in East Lansing show that such virus fragments can link up with other fragments to form a new virus.
Again, scientists don't know why this happens or how frequently it might occur. They don't even know whether the new viruses would be harmful. It's a warning not to take the new technique for granted as a benign alternative to pesticides until its basic biology is better known.
Meanwhile, at the University of California in Riverside, other researchers have shown that, contrary to expectations, hybrids formed by cross pollination between crops and nearby weedy relatives can be vigorous and hardy.
Crop-weed hybrids are an old story to farmers. Generally, plant varieties bred for cultivation can't survive without human care. Agriculturally desirable traits that they may pass to untamed relatives tend to put the crop-weed hybrids at a disadvantage in the wild. But if wild relatives gained herbicide resistance or some of the other exotic traits now being engineered into crop plants, they might turn into superweeds.
Genetic engineers have taken comfort in the expectation that any such crop-weed hybrids would not survive in the wild. Now they can't be so sure. It's another possible environmental impact to investigate when bringing a transgenic plant into cultivation.
Neither of these research reports provides reason to put genetic engineering of crops on hold. They define areas for vigorous research to find out what is going on. They also alert regulators and crop developers to new concerns that they should consider case by case in releasing genetically engineered plants for general use.
More important, these studies remind us that the open door of genetic engineering leads to a new and largely unknown world. The caution light glows brightly.