Effect of lignin content and structure on the anatomical, physical and mechanical properties of genetically engineered aspen trees.

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dc.contributor.advisor Ilona Peszlen, Committee Chair en_US
dc.contributor.advisor Perry Peralta, Committee Co-Chair en_US
dc.contributor.advisor Fikret Isik, Committee Member en_US
dc.contributor.advisor Stephen Kelley, Committee Member en_US
dc.contributor.advisor Daniel Saloni, Committee Member en_US
dc.contributor.author Horvath, Balazs en_US
dc.date.accessioned 2010-04-02T18:26:20Z
dc.date.available 2010-04-02T18:26:20Z
dc.date.issued 2009-06-30 en_US
dc.identifier.other etd-06142009-101426 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/3055
dc.description.abstract The effect of lignin genetic engineering on various wood properties were investigated for wild-type and transgenic quaking aspen (Populus tremuloides Michx.) groups with reduced lignin content, increased syringyl to guaiacyl (S/G) ratio, and both reduced lignin content and increased S/G ratio in four studies. In the first study, diameter growth and cell morphology of one-year-old transgenic aspen were assessed using quantitative wood anatomy and fiber quality analysis techniques. The genetic group with reduced lignin content had similar radial growth and quantitative anatomical properties, but the genetic group with increased S/G ratio had lower diameter growth and different vessel structure compared to the wild-type. The combined effect of lignin content and structural changes was more complex and gave inconsistent results. In the second study, dynamic modulus of elasticity (MOE) using a nondestructive acoustic technique and static MOE using micromechanical testing method were investigated for 2.5-year-old transgenic aspen. Results showed that all of the transgenics had lower MOE than the wild-type. In the third study, a dynamic mechanical analyzer (DMA) in static bending mode was used to determine the elastic modulus in water and ethylene glycol for 2.5-year-old transgenic aspen. Dynamic mechanical analyzer MOE values were compared to MOE values determined by nondestructive acoustic technique and micromechanical testing. All of the measured elastic moduli showed a similar trend of lower MOE for transgenics compared to the wild-type. In the fourth study, the in situ lignin glass transition of one-year-old transgenic aspen was investigated using a dynamic mechanical analyzer and a rheometer. Results suggested that an increase in the S/G ratio does not affect the glass transition temperature, but a reduction in lignin content decreased the softening temperature of transgenic wood. This research revealed that a reduction in lignin content had a more severe effect on wood properties than an increase in S/G ratio. However, diameter growth of transgenic trees with increased S/G ratio was lower. The combined effect of reduced lignin content and increased S/G ratio was inconsistent and needs further investigation. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Populus tremuloides Michx. en_US
dc.subject transgenic trees en_US
dc.subject lignin content en_US
dc.subject syringyl to guaiacyl ratio en_US
dc.subject wood anatomy en_US
dc.subject wood physics en_US
dc.subject wood mechanics en_US
dc.subject quaking aspen en_US
dc.title Effect of lignin content and structure on the anatomical, physical and mechanical properties of genetically engineered aspen trees. en_US
dc.degree.name PhD en_US
dc.degree.level dissertation en_US
dc.degree.discipline Wood and Paper Science en_US

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