Green Genes Blasted into Chloroplasts
Weiss, Rick, Science News
Green genes blasted into chloroplasts
After years of failed efforts, scientists working with flowering plants have inserted foreign genes into chloroplasts -- the tiny, chlorophyll-packed sacs that green plants use to convert sunlight into usable energy. Researchers say the new-found ability to genetically manipulate these solar-powered substations opens the door to a host of improvements in crops.
"It's a big hurdle, a very significant step forward," says Wilhelm Gruissem, a botanist at the University of California, Berkeley. "Many people are going to want to use this technique."
Most plant genes reside within the cell nucleus, but a few genes critical for photosynthesis remain cloistered in the 100 to 300 chloroplasts scattered through the rest of the cell. Molecular biologists have become reasonably adept at inserting and deleting nuclear genes, and in 1988 scientists succeeded in altering the genetic sequence of chloroplasts in primitive algae bearing only one chloroplast per cell. But until now, nobody had genetically altered the more complex chloroplasts in higher plants.
The new work, described in the November PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (Vol.87, No.21), was performed by Zora Svab, Peter Hajdukiewicz and Pal Maliga of Rutgers University in Piscataway, N.J. Working with tobacco seedlings grown in culture plates, the team sought to insert two new genes into the chloroplasts. The genes enable plant cells to resist antibiotics that would otherwise inhibit photosynthesis.
The researchers blasted the seedlings with tiny tungsten pellets coated with multiple copies of the antibiotic-resistance genes. When grown on a special growth medium containing antibiotics, most of the seedlings turned white, indicating that they had not incorporated the resistance genes and that their photosynthetic machinery had succumbed to the drugs. …