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Doctoral thesis, 2013

Metabolomics and wood development

Johansson, Annika


The tree industry is one of Sweden's most important economic sectors, producing pulp, paper, wooden goods and wood as a bioenergy source. Understanding the biology behind the processes of tree growth and wood development is a key to maximizing the use of wood as raw material. The term "metabolome" refers to the complete set of small-molecule metabolites to be found within a biological sample. Since metabolites can be viewed as down-stream products of gene transcription, protein expression and enzymatic activity the metabolites are believed to reflect activity in cells more accurately than the transcript and protein complements. Metabolomics aims to identify and quantify all metabolites in a biological sample and thereby link biochemical information to a phenotype. In the course of the work underlying this thesis we have developed analytical tools for metabolomics and applied these tools to reveal metabolite patterns, with a focus on various aspects of wood development. Firstly we development of a rapid and reliable method for processing GC-TOFMS data, that enables us to move from GC-MS chromatograms via metabolite identification to biological interpretation. To address the low identification ratios characteristic of GC-MS metabolomics studies, a database containing the predicted retention indices of ~13 000 metabolite structures was developed. Since metabolomic studies only gives a snapshot of the metabolic status of a cell and it is the metabolic fluxes within the cell that are the key determinant of cell activity, an LC-MS based method for the measurement of nitrogen fluxes was evaluated using plants fed with ¹⁵N. As winter approaches trees in temperate zones halt the growth of the vascular cambium and put the meristems into a dormant state. In order to gain a better understanding of the environmental and hormonal regulation of the process of activity-dormancy transitions in aspen trees we performed metabolite profiling of the cambial tissue at different stages over the year. Finally a metabolic roadmap of wood development in Populus was created by combining targeted analysis of plant hormones and amino acids in parallel with high sensitivity untargeted LC-MS and GC-MS analyses. We were able, for the first time in a plant metabolomics study, to describe changes in metabolite profiles following the route of differentiation from cell division to cell death.


metabolomics; wood development; mass spectrometry; retention index; QSRR; nitrogen flux

Published in

Acta Universitatis Agriculturae Sueciae
2013, number: 2013:92
ISBN: 978-91-576-7922-2, eISBN: 978-91-576-7923-9
Publisher: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology

UKÄ Subject classification

Biochemistry and Molecular Biology
Analytical Chemistry
Developmental Biology

URI (permanent link to this page)