Corn yields to genetic tinkering.

Corn yields to genetic tinkering 

California researchers have achieved a long-awaited first by growing corn plants genetically engineered to carry a foreign gene.

Inserting foreign genes into plants is not new; scientists have been engineering broad-leaved, dicot plants such as tobacco and tomatoes for more than a decade. But until now the monocot grain crops, such as corn and rice, have been notoriously hard to engineer. These difficulties have left the world's important cereal crops almost untouched by advances in genetic engineering.

In the recent work with corn, scientists at the Sandoz Plant Protection Corp. in Palo Alto, Calif., Inserted a gene for antibiotic resistance into specially prepared corn-plant cells called protoplasts, and grew the protoplasts into whole corn plants. Each cell in the new plants carries the foreign gene.

Years of painstaking research led to this success. First, other scientists got foreign genes to pass into corn protoplasts but couldn't get the protoplasts to grow into full plants. Early this year researchers reported that they had grown genetically unaltered corn protoplasts into full corn plants. The growth of full plants from genetically altered protoplast, reported in the April 8 issue of SCIENCE, was the logical combination of these results.

The corn plants' resistance to the antibiotic is not useful in itself, but the antibiotic-resistance gene can be paired with a more useful gene. Then the presence of antibiotic resistance will how which plants have also taken up the useful gene. Genes for resistance to herbicides and to corn-eating pests are likely candidates for future insertion into corn plants. Now that corn has been engineered by this method, other cereal crops may soon follow, according to Carol Rhodes, one of the report's authors.

There remains one major problem with the engineered corn plants: They produce no corn. The researchers, however, think this may be just a result of the techniques used and say they expect this problem to be solved in the future. "I don't know how long it will be," says Rhodes, "but it's definitely going to happen."