title: Reduced wood stiffness and strength, and altered stem form, in young antisense 4CL transgenic poplars with reduced lignin contents.
abstract: • Reduced lignin content in perennial crops has been sought as a means to improve biomass processability for paper and biofuels production, but it is unclear how this could affect wood properties and tree form. • Here, we studied a nontransgenic control and 14 transgenic events containing an antisense 4-coumarate:coenzyme A ligase (4CL) to discern the consequences of lignin reduction in poplar (Populus sp.). During the second year of growth, trees were grown either free-standing in a field trial or affixed to stakes in a glasshouse. • Reductions in lignin of up to 40% gave comparable losses in wood strength and stiffness. This occurred despite the fact that low-lignin trees had a similar wood density and up to three-fold more tension wood. In free-standing and staked trees, the control line had twice the height for a given diameter as did low-lignin trees. Staked trees had twice the height for a given diameter as free-standing trees in the field, but did not differ in wood stiffness. • Variation in tree morphogenesis appears to be governed by lignin x environment interactions mediated by stresses exerted on developing cells. Therefore our results underline the importance of field studies for assessing the performance of transgenic trees with modified wood properties.
authors.affiliation: Department of Wood Science & Engineering, Oregon State University, Corvallis, OR 97330, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Voelker
authors.affiliation: Department of Wood Science & Engineering, Oregon State University, Corvallis, OR 97330, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Lachenbruch
authors.affiliation: USDA Forest Service, Pacific Northwest Research Station, 3200 Jefferson Way, Corvallis, OR 97330, USA.
authors.forename: Frederick C
authors.initials: FC
authors.lastname: Meinzer
authors.affiliation: Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97330, USA.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Strauss
mesh_terms: D000704:Analysis of Variance; D018533:Biomass; D001696:Biomechanical Phenomena / Q000502:physiology; D003066:Coenzyme A Ligases / Q000378:metabolism*; D055119:Elastic Modulus; D008031:Lignin / Q000378:metabolism*; D018547:Plant Stems / Q000033:anatomy & histology*; D030821:Plants, Genetically Modified; D032107:Populus / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D016372:RNA, Antisense / Q000378:metabolism*; D014934:Wood / Q000033:anatomy & histology / Q000502:physiology*
chemical_list: D016372:RNA, Antisense; D008031:Lignin; D003066:Coenzyme A Ligases