Scientists have, for the first time, genetically engineered the parts of plant cells where photosynthesis occurs.

Rutgers University researchers said they have introduced genetically altered material into the chloroplasts of a tobacco plant, whose seeds produced plants that carried the same traits.Photosynthesis occurs in chloroplasts, the tiny structures in plant cells that contain chlorophyll. Photosynthesis is the fundamental process by which plants make food and capture the sun's energy.

"We now have this tool to genetically improve photosynthesis, to make it more efficient," said Pal Maliga, the director of Rutgers' research team.

Improved photosynthesis could eventually make for bigger and sturdier plants that could more efficiently produce food in a shorter amount of time, Maliga said.

Scientists in other parts of the country hailed the Rutgers finding as a breakthrough.

"It certainly is a first in higher plants," said Milton Zaitlin, the director of the biotechnology program at Cornell University in Ithaca, N.Y.

"It's a major breakthrough," said Richard Hallick, a biochemist at the University of Arizona. "It's something that has been sought for at least a decade."

The results of the experiment were reported Thursday in The Proceedings of the National Academy of Sciences, a scientific journal.

Photosynthesis is fundamental to all plant and animal life because it provides the carbohydrates to power their metabolic processes.

In photosynthesis, green plants use sunlight to make carbohydrates from carbon dioxide and water in the presence of chlorophyll.

All fossil fuels - coal, oil and natural gas - originally captured their energy from the sun through photosynthesis.

One of the first commercial spinoffs could be to engineer plants resistant to herbicides, said Randall Hauptmann, director of the Plant and Molecular Biology Center at Northern Illinois University in DeKalb.

Many herbicides work through the photosynthetic process to kill weeds. Farmers could apply herbicide to kill weeds while not hurting the resistant crops, he said.

In the long term, scientists could use the findings to explore ways of developing plants resistant to drought or low temperatures, Maliga said.

"We want crop plants to perform to serve human needs, which wasn't the object of evolution," Maliga said.

Three compartments in plant cells contain genes - the nucleus, chloroplasts and mitochondria.

Scientists have introduced altered genes into the nucleus, and most biotechnological innovation to date comes from this method of transformation.

Researchers have also introduced genetically altered material into the chloroplasts of algae, but never before into the chloroplasts of higher plants or into mitochondria.

Maliga and two other scientists - Zora Svab and Peter Hajdukiewitz - worked on the two-year project under a grant from the New Jersey Science Initiative.

The team coated microscopic tungsten particles with an altered chloroplast gene from a tobacco plant. Using a "particle bombardment process," the team used a special gun to spray the cells with the tiny pellets.

The scientists then used the cells to raise plants that were genetically stable. The new plants produced seeds that contained the altered genes.

"We can do it on a regular basis, but it is inefficient," Maliga said. "We want to make it a tool available to all plant scientists."