Bound Volume Number


Degree Type

Honors Capstone Project

Date of Submission

Spring 5-1-2015

Capstone Advisor

Dr. Heather Coleman

Honors Reader

Dr. James Hougland

Capstone Major


Capstone College

Arts and Science

Audio/Visual Component



bioethanol production, biofuels production

Capstone Prize Winner


Won Capstone Funding


Honors Categories

Sciences and Engineering

Subject Categories

Biochemistry | Biotechnology | Cell Biology | Genetics


Plants with polysaccharide-rich secondary cell walls have great potential as a source of carbohydrates for bioethanol production. However, the presence of phenolic lignin inhibits the isolation of bioethanol precursors cellulose and hemicellulose from the secondary cell wall. Recent studies have linked nitrogen availability to secondary cell wall development and composition, making nitrogen metabolism genes an interesting target in the improvement of plant cell walls for biofuels production. Plants use a nitrogen assimilation pathway to convert inorganic nitrogen sources into organic sources, included amino acids, which play key roles in metabolism and cell wall development. Asparagine synthetase (AS), a key enzyme involved in the nitrogen assimilation pathway, produces asparagine from aspartate and either glutamine or ammonium. As asparagine is one of the major translocatable forms of nitrogen in poplar, AS has been selected for analysis in this study. Initially, gene profiling of the AS gene family will be conducted using hybrid poplar as a model organism to elucidate AS expression patterns throughout the plant tissues. Primers for RT-PCR have been generated and optimized for analysis of relative expression levels of different tissues at different developmental stages to localize where and when AS is most highly expressed. Transgenic poplar harboring AS are being regenerated and will be assessed for changes in development, growth and cell wall chemistry and structure. Nitrogen fertilization resulted in a significant difference in growth between no nitrogen and low nitrogen treatments in P39 hybrid poplar, but not between any other treatments. There was a difference in growth between 717 and P39 poplar hybrids, where the 717 hybrids grew to be statistically significantly taller. The results of this project will be used in the development of a model of how nitrogen assimilation impacts cell wall formation in poplar.

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Creative Commons Attribution 3.0 License
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