Project leader: Gunnar Henriksson

Characterization of lignin from surface cell wall layers

Aim: Isolate and characterize lignin from outer cell wall layers

Background: The projects goal is to obtain information regarding the differences in the lignin structure within the individual cell walls, i.e., the cell wall layers in spruce and aspen. It has been suggested that such differences occur, but the experimental evidence for this have so far been limited, to a large extent due to the difficulties in obtaining sufficient amounts of material for lignin analysis of separate cell wall layers. In this project we prepare plant materials enriched in primary cell wall/middle lamella/S1 layers and analyze the lignin structures with GC-MS, GPC and NMR. To verify that the material has an increased proportion of outer cell wall material AFM and confocal microscopy are employed. Carbohydrate monomer distribution is also determined since it is diagnostic for different cell wall layers.

Project description: So far three different sources for plant materials with an increased amount of outer cell layers as compared to woody tissue, which contain mostly secondary cell, wall have been analyzed.

Firstly poplar cell suspension cultures, have been investigated.

Secondly, three approximately 10 year old aspen trees were collected at the end of June 2003, frozen and de-barked while semi frozen. Thereafter the phloem rich region inside the bark and the xylem rich side of the log were collected separately by scraping the semi frozen tissue with scalpels. This area, the vascular region, produces new cells for the tree and even though some of these cells contain secondary cell walls the hypothesis was that in early summer  most of the cells that produce secondary cell walls would not have had time to lignify the inner layers yet.

Thirdly, white spruce that have been preserved under anaerobic conditions for 10 000 years has been investigated. The sample has an intact outer cell wall and middle lamella, but the secondary cell wall have been selectively removed by microorganisms.

Project group
Gunnar Henriksson, KTH
Maria Christiernin
, Ph.D student, KTH

Competence linked to the group:
Anna Ohlsson, KTH
Torkel Berglund, KTH
Liming Zhang, KTH
Shannon Notley, KTH