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U.S. Department of Energy, Office of Science
Poplar Genome Based Research for Carbon Sequestration in Terrestrial Ecosystems |
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Principal investigator:
Vincent L. Chiang, North Carolina State University vincent_chiang@ncsu.edu Co-investigator: Kurt S. Pregitzer, Michigan Technological University Project period: March 2004 to present ER63754 |
Effects of down- and up-regulated lignin biosynthesis in Populus on soil carbon transformation and storage
Summary: A common genome experiment was conducted that combined carbon isotope tracing techniques with transgenic plants to examine lignin controls on plant growth and soil processes. The control line was a wild-type clone of trembling aspen. There were three different transgenic lines derived from this clone expressing reduced stemwood lignin concentrations or altered stemwood syringyl:guaiacyl lignin ratios. The two low lignin lines accumulated 15-17% less root carbon and 33-43% less new soil carbon than the control line, while maximum photosynthesis, specific leaf area, and aboveground biomass did not differ from controls. Aspen with high syringyl:guaiacyl lignin ratio, but no change in stemwood lignin or cellulose concentrations, accumulated 30% less total plant carbon, resulting from large reductions in plant height, total leaf area, and specific leaf area. Further, these plants accumulated 70% less new soil carbon and 40% less microbial biomass carbon in comparison to control and low lignin lines. Altered lignin biosynthesis in aspen trees altered plant growth, biomass partitioning, and soil carbon formation. |