Forest Products Biotechnology Laboratory
Dr. Kyung-Hwan Han
Project Summary:
We are taking a metabolic engineering approach for producing value-added hardwood products through. We will use an enhanced decay resistance of wood to demonstrate the feasibility of this approach. If successful, the outcome will be trees with high levels of heartwood extractives that render them decay resistant. Compared to conventional methods of wood preservation, use of decay-resistant wood can be both economically efficient and environmentally sound. We chose black locust and poplar to work with for this project for several reasons. To minimize the concerns for environmental bio-safety from the use of genetically engineered trees, we intend to limit the expression of the introduced gene in the wood tissues. For this we will we will identify trunk wood-specific genes and subsequently their promoter regions. The promoter region of the genes will then be used to drive our genes of interest; thus the introduced genes will be expressed only in the specific tissue.
In order to demonstrate the feasibility of our metabolic engineering approach, we are using a regulatory gene for flavonoid pathway, which is responsible for the production of various flavonoids that contribute to the decay resistance of black locust. Over-expression of the CRC gene has shown to increase total flavonoid concentration in transgenic plants. The resulting transgenic trees are expected to have enhanced decay resistance. Successful completion of this project will allow us to directly apply the technology to other commercially valuable hardwood species.
Key Words:
Current Project:
Metabolic Engineering of hardwood species for value added wood products:
In this study, we pursue the following objectives:
Develop a biotechnological means for production of value-added wood products,
Identify the genes expressed in sapwood-heartwood transition zone and the promoters of the wood-specific genes,
Study gene expression profile in trunk wood using DNA arrays,
Produce transgenic trees over-expressing flavonoids genes for enhanced decay resistance,
Analyze chemical composition and test the transgenic trees for decay resistance.
Develop DNA-based detection system for incipient fungal decay in wood products
We are taking a metabolic engineering approach for producing value-added hardwood products. An enhanced decay resistance of wood will be used to demonstrate the feasibility of this approach. If successful, the outcome will be trees with high levels of heartwood extractives that render them decay resistant. Compared to conventional methods of wood preservation, use of decay-resistant wood can be both economically efficient and environmentally sound. We chose black locust and poplar to work with for this project for the reasons given below. Stable gene insertion systems are currently available for the species. We will use those protocols to produce transgenic trees with selected genes.
In order to minimize the concerns for environmental bio-safety from the use of genetically engineered trees, it is important to limit the expression of the introduced gene in the wood tissues. As a step toward achieving this, we will identify the genes specifically expressed in the trunk wood. The promoter region of the genes will then be used to drive the genes of interest, thus the introduced genes will be expressed only in the specific tissue. We have already identified a large number of genes that are highly expressed in the trunk wood of mature black locust. We are using chalcone synthase (CHS) and its regulatory gene CRC (Bruce et al., 2000). CHS is a key regulatory enzyme for the production of various flavonoids that contribute to the decay resistance of black locust. Over-expression of the CRC gene has shown to increase total flavonoid concentration in transgenic plants (Bruce et al., 2000). We have obtained the construct and currently using it in our transformation experiments. The resulting transgenic trees are expected to have enhanced decay resistance. Successful completion of this project will allow us to directly apply the technology to other commercially valuable hardwood species.
Michigan State University is an Equal Opportunity / Affirmative Action Employer
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