Scientists study cottonwood trees for biofuel

STARKVILLE — In a quest to identify economically and agriculturally sustainable biofuels to reduce dependence on foreign energy suppliers, U.S. scientists and engineers constantly are identifying methods of converting biomass into biofuel products.

This year, Mississippi State University researchers announced a breakthrough in understanding how cottonwood trees begin to produce seasonal flower buds.

This critical development may help accelerate domestication of these trees for biomass and other products. Findings of the research were significant enough to be reported recently in the Proceedings of the National Academy of Sciences.

“Cottonwood trees increasingly are grown in plantations as economically important, fast-growing woody crops for bioenergy, wood, fiber and carbon sequestration,” said Cetin Yuceer, co-author of the report.

An assistant forestry professor, he directs MSU’s international molecular forest technology laboratory.

“Agricultural crops have been domesticated because they produce flowers within several months from seed sowing,” Yuceer said. “Trees primarily are undomesticated, in part, because of the lengthy juvenile period between seed germination and the formation of the first flower buds.”

Forest trees usually do not form flower buds before growing five years or longer, he observed.

“I can only do a few cycles of tree breeding during my career,” Yuceer said. “Thus, the goal of our research was to discover the major genes and their associated environmental factors which regulate flowering onset in trees.

“If we can determine ways to regulate genes that control the onset of flowering in trees so they will breed faster, we can increase their biomass yield and resistance to environmental stress, which will result in greater economic value.”

Since flowers are necessary for breeding, Yuceer and his team are working to determine how flowering may be induced in trees at earlier ages to accelerate breeding.

Funded through an Early Career Development Award from the National Science Foundation, his research has revealed that cottonwood trees induce flower bud production through activation of the FT1 gene after weather turns cold in the winter, when they are dormant. Traditionally, scientists thought trees began flower bud productions in the spring.

Chuan-Yu Hsu, a forestry research associate and the journal article’s other author, further explained the MSU research. She said FT1 influences cells responsible for cottonwood bud growth during the dormant state. The gene quickly is turned off as temperatures rise in early spring, marking the end of floral onset and beginning of floral bud development. A sister of FT1, the FT2 gene then is activated to produce vegetative growth that provides energy to rapidly developing flower buds.

Yuceer said their research should help scientists identify whether other tree species, such as pines and oaks, have a similar genetic mechanism. Future research also will seek to determine why the FT1 gene does not become active at earlier ages in cottonwood trees.