title: Lignin biosynthesis in transgenic Norway spruce plants harboring an antisense construct for cinnamoyl CoA reductase (CCR).
abstract: An attractive objective in tree breeding is to reduce the content of lignin or alter its composition, in order to facilitate delignification in pulping. This has been achieved in transgenic angiosperm tree species. In this study we show for the first time that changes in lignin content and composition can be achieved in a conifer by taking a transgenic approach. Lignin content and composition have been altered in five-year-old transgenic plants of Norway spruce (Picea abies [L.] Karst) expressing the Norway spruce gene encoding cinnamoyl CoA reductase (CCR) in antisense orientation. The asCCR plants had a normal phenotype but smaller stem widths compared to the transformed control plants. The transcript abundance of the sense CCR gene was reduced up to 35% relative to the transformed control. The corresponding reduction in lignin content was up to 8%, which is at the lower limit of the 90-99% confidence intervals reported for natural variation. The contribution of H-lignin to the non-condensed fraction of lignin, as judged by thioacidolysis, was reduced up to 34%. The H-lignin content was strongly correlated with the total lignin content. Furthermore, the kappa number of small-scale Kraft pulps from one of the most down-regulated lines was reduced 3.5%. The transcript abundances of the various lignin biosynthetic genes were down-regulated indicating co-regulation of the biosynthetic pathway.
authors.affiliation: Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences (SLU), P.O. Box 7080, 750 07 Uppsala, Sweden. johan.wadenback@vbsg.slu.se
authors.forename: Johan
authors.initials: J
authors.lastname: Wadenbäck
authors.forename: Sara
authors.initials: S
authors.lastname: von Arnold
authors.forename: Ulrika
authors.initials: U
authors.lastname: Egertsdotter
authors.forename: Michael H
authors.initials: MH
authors.lastname: Walter
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Grima-Pettenati
authors.forename: Deborah
authors.initials: D
authors.lastname: Goffner
authors.forename: Göran
authors.initials: G
authors.lastname: Gellerstedt
authors.forename: Terry
authors.initials: T
authors.lastname: Gullion
authors.forename: David
authors.initials: D
authors.lastname: Clapham
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D016373:DNA, Antisense / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000096:biosynthesis* / Q000235:genetics; D008954:Models, Biological; D028222:Picea / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D018547:Plant Stems / Q000033:anatomy & histology; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000378:metabolism; D019076:Transgenes; D014934:Wood / Q000378:metabolism / Q000502:physiology
chemical_list: D016373:DNA, Antisense; D012333:RNA, Messenger; D008031:Lignin; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase