The project will use the herbaceous plant, Arabidopsis thaliana, as a model for the study. Beers' previous research was the first to demonstrate that Arabidopsis is a good model for studying the molecular biology of wood formation*. Arabidopsis is a small plant with a short life cycle; a great deal of information is available on it because its entire genome has been sequenced. This wealth of genomic information coupled with the variety of research techniques and other resources that have been developed for use with Arabidopsis make this small weed a powerful model. Despite its diminutive size, Arabidopsis produces wood that closely resembles that produced by commercially important trees species such as poplar and pine.
"The Arabidopsis genome contains about 25,000 genes. Figuring out which ones are required for a plant to produce wood is the challenge we face," Beers said.
Graduate student Chengsong Zhao measured the genes expressed in wood isolated from Arabidopsis using technology available at the Virginia Bioinformatics Institute at Virginia Tech. The technology is capable of measuring expression of all 25,000 Arabidopsis genes simultaneously. With this information, Beers and his collaborator Allan W. Dickerman, research assistant professor at the Virginia Bioinformatics Institute, were able to reduce the number of possible wood formation genes from 25,000 possibilities down to less than 500.
"From among this relatively small number of possible wood-forming genes, we concentrate on the genes that code for transcription factors because they function as master regulators and thereby have profound impacts on developmental processes," Beers said. By identifying transcription factors that were expressed only in woody tissue, they were able to select the genes most likely to regulate wood development.
Chengsong Zhao demonstrated that one of the identified wood transcription factors showed potential as a regulator of xylem development. Xylem is the wood-forming tissue in plants.
"By further manipulating this gene and others we have identified as potential regulators of wood formation, we will have a better understanding of how plants produce this valuable commodity upon which we all rely," said Beers.
* Zhao, C., B.J. Johnson, B. Kositsup, E.P. Beers, 2000, Exploiting secondary growth in Arabidopsis: Construction of xylem and bark cDNA libraries and cloning of three xylem endopeptidases. Plant Physiology, 123: 1185-1196.