Poplar tree forest
Fast-growing poplar trees are a potential source of bioenergy. A new project led by Nitzan Shabek at the UC Davis Department of Plant Biology will look at growth regulation in these trees, especially in drought conditions. (Photo by David Gilbert for US DoE Joint Genome Institute.)

Understanding Growth Regulation by Protein Degradation in Trees for Bioenergy

The U.S. Department of Energy is funding a project at the UC Davis College of Biological Sciences to study the function of genes that regulate growth and wood formation in poplar trees. The three-year, $2.5 million project is led by Nitzan Shabek, assistant professor in the UC Davis Department of Plant Biology together with Andrew Groover at the USDA Pacific Southwest Research Station in Davis and Justin Walley, Iowa State University.

Poplar has potential as both a solid biofuel and for making liquid fuels. The fast-growing trees can be harvested in two to five years of planting.

Growth and wood formation in trees is controlled by a complex set of proteins produced by various genes. The levels of specific proteins are set by the balance between how quickly they are produced by gene expression, and how rapidly they are removed by the ubiquitin proteasome system, the ‘waste disposal’ system inside cells. This regulation is highly important when growth rates are impacted by drought.

The project is designed to take advantage the distinct expertise of the groups. Groover’s team has carried out extensive research on wood formation in poplar, including the regulation of diameter of water conducting cells. Walley’s team studies the biology of regulatory pathways using multiomics approaches, and Shabek’s group at UC Davis studies the structure and function of the ubiquitin system in plants.

The new project aims to functionally profile and characterize key components of ubiquitin-proteasome regulation of protein levels in trees using poplar as models with the ultimate goal of developing models that can predict processes for the best biomass yield and bioenergy applications.

The grant is among $178 million in funding for sustainable bioenergy research announced by the Department of Energy Sept. 13. 

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