Fast-growing switchgrass yields double starch content
From the San Francisco Chronicle
One day in the not-too-distant future, we might be filling our cars with fuel made from useless grass.
A Berkeley biologist has transferred a gene from a variety of corn into a widespread, fast-growing species of the grass, and transformed it into what could become an important source of biofuel.
In a world of vanishing oil reserves, farmers have been growing more and more high-energy crops like corn and sugar cane to make ethanol as a replacement for gasoline, while scientists are seeking even higher-energy products from other and better crops.
Now George S. Chuck, a UC Berkeley plant geneticist, reports that his experiments with a species of corn called corngrass1 have yielded genetically altered forms of common switchgrass plants that more than doubles their content of starch.
The starch, in turn, creates sugars that when fermented - as in all biofuel plants - produce the ethanol that goes into more and more cars today.
Chuck and his colleagues are working at the Agriculture Department's Plant Gene Expression Center in Albany.
In a report published this week in the Proceedings of the National Academy of Sciences, the scientists say that test plots of the altered switchgrass have shown that the gene experiments have improved the starch yield in the plants by "up to 225 percent." Also important, they report, the gene transfer blocks the switchgrass plants from flowering.
"They're forever young," Chuck said - and that means the plants cannot spread pollen containing the new gene beyond the area where the altered plants grow.
Up to now, the fast-growing switchgrass, because of its tough lignin, an organic polymer, has required heavy chemical treatment before it can be turned to ethanol as biofuel. Chuck's gene transfer experiments have shown that because the improved switchgrass keeps the plants young, the lignin content of their cells is minimal and would need no chemical treatment, he reported.
Edward M. "(Eddy)" Rubin, an internationally noted geneticist and director of the Department of Energy's Joint Genome Institute in Walnut Creek, called Chuck's report "both interesting and important."
"This is an illustration of how manipulating the genome of a plant can make an incredibly useful change in the plant as a source of energy," Rubin said.
Chuck's gene-cloning experiments represent five years of work, Chuck said in an interview Tuesday.
Now, larger field tests of the transformed switchgrass are planned, and Chuck said he is starting a new series of genetics experiments to see how other genes from the corngrass1 plant can be "turned on" in response to light and darkness, and to raise the starch content of switchgrass even higher. The goal is a major new source of biofuel from a wild plant that grows throughout the world.
But drivers will have to be patient.
"It won't all happen tomorrow," he said.
By David Perlman, San Francisco Chronicle