Ice Fishing
Shui-zhang Fei
Model plants are the "proving grounds" for new crops. Temperate grasses are candidates for making cellulosic ethanol, and Brachypodium distachyon is fast becoming a model for these new bioenergy crops.
Compared to rice, another popular grass model species, Brachypodiumhas a slightly smaller genome, shorter life cycle, shorter stature and a well-established genetic manipulation protocol. More importantly, it has the ability to acclimatize to cold, which rice does not. Freeze toler- ance is important in temperate grasses because they are perennial-growing back each year.
Freeze tolerance develops when days shorten and temperatures begin to dip. "The plants sense when winter is coming," explains Shui-zhang Fei, associate professor in the Department of Horticulture, and make appropriate biochemical changes in their membrane composition or produce cryopro- tectants that protect against freezing.
With support from the institute's Innovative Grants Program, Fei with col- leagues Kan Wang, professor in the Department of Agronomy, and Yanhai Yin, assistant professor in the Department of Genetics, Development and Cell Biology, are working to establish an experimental collection of Brachypodium plants which select genes believed to be crucial to biofuel feedstock adaptation are silenced - initially, those involved in cold acclimatization and the brassinosteroid signaling pathway.
First though, the team needed to confirm Brachypodium's ability to develop freeze tolerance. Exposing plants to four-degree- centigrade temperature bouts for zero, three, seven and fourteen days, Fei and his colleagues found that Brachypodium acclimatizes to cold within two weeks.
The team selected eight genes impli- catedin cold acclimatization, genes that cause obvious phenotypical changes. Fei is not sure yet if these make up a master switch, but all eight appear to be transcrip- tion factors that can have profound effects on the expression of many other genes.
"Molecular biology is like deep sea fishing," says Fei. "You sit on the surface and can only speculate what is happening at the end of your line."
The researchers are now trying to probe those depths by perturbing the genes that might be involved in freeze tolerance using tools such as RNA silencing vectors, overexpression vectors, transforming the plants and selecting transgenic lines for further study.
