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Doctoral thesis, 2010

Integration of Arabidopsis and poplar model systems to elucidate gene function during wood formation

Edvardsson, Ellinor


Wood is an essential raw material being used for a number of different applications including construction, pulp and paper production and as a source of biomass for bioenergy generation. The increasing number of sequenced plant genomes provides powerful tools to evaluate plant gene function. Cross-species integration is increasingly being used as a way to facilitate gene discovery and functional characterisation. In this thesis poplar and Arabidopsis model systems were integrated with the aim of identifying and characterising cell wall biosynthesis or modifying genes. Wood forming tissues of poplar represent an ideal model system to study developmental processes from cell division through to cell death. However, the relatively large size and slow growth rate of poplar make it practically challenging to use as an experimental system. An alternative is to identify closely related genes in Arabidopsis where their function can be analysed using T-DNA knockout lines and then transfer this knowledge back to tree species. Transcriptomics data for the wood forming tissues of poplar was used to identify genes which were specifically upregulated in the zone of secondary wall formation. Several of these poplar genes were used to identify the closest Arabidopsis homologs in a 3-step screening filter. One of these genes was selected for further analysis in Arabidopsis resulting in the identification of a small family of 4 related sequences which were named DUF DOMAIN PROTEINs (DDPs). T-DNA knockouts were generated for each of the genes and all possible mutant combinations made. ddp mutants affected root elongation, lateral root formation and seed development. Analysis of the biochemical composition of the ddp mutant combinations revealed possible changes in the relative amount of hemicellulose, pectin and/or lignin, compounds important in the secondary cell wall. The Arabidopsis epc1 mutant was identified previously as having severe growth defects, with reduced cell-cell adhesion and increased secondary growth. Two poplar EPC1 homologs were identified and complementation studies show that they are able to rescue the Arabidopsis epc1 mutant. RNAi downregulation of PtEPC1 resulted in only minor effects on growth which may be due to residual message producing sufficient functional protein.


arabidopsis; populus; lignification; models; genes; cell walls; genetics

Published in

Acta Universitatis Agriculturae Sueciae
2010, number: 2010:31
ISBN: 978-91-576-7508-8
Publisher: Dept. of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences

Authors' information

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

UKÄ Subject classification

Plant Biotechnology

URI (permanent link to this page)