Plant & Animal Genome IX Conference

Workshop: Forest Tree Genome Mapping
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GENOMICS OF WOOD FORMATION IN BLACK LOCUST

¹ Department of Forestry, Michigan State University, 126 Natural Resources, East Lansing, MI 48824-1222

² Academic Health Center, University of Minnesota, 650 Children's Rehabilitation Center, UMHC 43, 426 Church St. S.E., Minneapolis, MN 55455-0312

Trees have the ability to undergo secondary growth and produce a woody body. Although trees comprise over 90% of the terrestrial biomass of the earth, knowledge of this unique biological process is limited because: 1) forward genetic approaches are hampered by long generation times, 2) comparative molecular genetics studies have limited use since most model organisms do not undergo secondary woody growth, and 3) it is difficult to experimentally observe the complex metabolic changes inside tree trunks. We are taking a genomics-based approach to understand the molecular biology of wood formation and the processes by which its extractives are produced and stored. Isolation of high quality mRNAs from the cells inside trunk wood has been difficult for several reasons. In spite of this, we have successfully made cDNA libraries from the trunk wood of a mature black locust, and have begun generating expressed sequence tags (ESTs) from the libraries. Approximately 3,000 ESTs have been identified and annotated using BLAST search. While more than 50% of the ESTs derived from sapwood-heartwood transition zone and cambial region had significant homology to previously reported sequences, about 80% of the ESTs from the sapwood library did not have any homology to reported sequences. These ESTs can also be used as molecular markers in tree genome projects. We are currently working to fabricate the ESTs into DNA arrays and carry out hybridization experiments to obtain gene expression patterns in trunk wood. The results from both the EST analysis and DNA array experiments will be presented.