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Improving biomass production in trees - exploitation of transcription factors |
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The proposed PhD project will focus on identifying the key regulators of growth and biomass production using hybrid aspen and Arabidopsis thaliana. In the first part of the project an existing collection of transcription factor overexpressing hybrid aspen plants will be screened to identify transcriptional regulators enhancing growth. In a related approach we will also identify regulators that will alter seasonal responses to extend the growing season and improve stress tolerance especially as the length of growing season and low stress tolerance are major limitations to biomass production in the northern latitudes. Once the key regulators are identified their downstream targets will be identified through overexpression using inducible and tissue specific promoters and RNAi based downregulation to gain further knowledge about their mode of action.Supervisor: Rishi Bhalerao (
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PhD student: Szymon Tylewicz |
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Improving biomass production in trees – diversion of the carbon flow |
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The aim of the PhD project is to increase the amount of carbon allocated to cellulose biosynthesis. We have ongoing research on several novel candidate genes/proteins in the biosynthesis of cellulose. In this project the PhD student will unravel the function and biochemistry of these genes/proteins as well as study the regulation of known components in cellulose biosynthesis. Both Arabidopsis thaliana and hybrid aspen are used as model systems. The student will have the opportunity to be trained in state-of-the-art techniques in Arabidopsis and aspen genetics, plant molecular biology, biochemistry, cell wall analysis and microscopy. Flexibility to travel is required, as part of the research will be carried out at the Max Planck Institute for Molecular Plant Physiology in Germany.
Supervisor: Totte Niittylä (
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Improving biomass production in trees – Stimulation of cambial activity |
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This project focuses on the growth control of the vascular cambium, which is the meristematic region of the tree stem determining how much wood is produced, and investigate whether the same regulatory loops that control shoot apical meristem identity and activity are also operating in the vascular cambium. We have already found that an aspen tree gene, PttWOX4, which is similar to a gene that is necessary for shoot apical meristem identity is also necessary for the identity and activity of the vascular cambium. We have also found several other Populus genes, that together with this gene seems to be involved in a regulatory loop controlling the activity of the vascular cambium. We will characterize RNAi lines and overexpression lines of these genes in transgenic hybrid aspen and Arabidopsis, and determine how these genes affect biomass production and other properties of wood such as the saccharification potential.
Supervisor: Ove Nilsson (
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Recalcitrance of the lignocellulose – focus on lignin |
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In this PhD project, novel genes in lignin polymerisation will be identified using two complementary biological systems – one simplified (in vitro cell culture) and one integrated (whole hybrid aspen trees). The overall research strategy resides in using first the simplified system to rapidly and specifically identify and characterise lignin polymerisation candidate genes by combining bioinformatic and proteomic approaches. The most interesting candidate genes will then be functionally demonstrated in the in vitro cell culture using stable transgenic cell lines for overexpression and RNAi. The resulting best candidate genes will then be similarly functionally characterised in hybrid aspen by producing stable transgenic poplar trees for overexpression and RNAi. In each case, the impact on lignification will be estimated using both microscopical and biochemical (wood chemistry, saccharification) techniques.
Supervisor: Edouard Pesquet (
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Recalcitrance of the lignocellulose – focus on cellulose |
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Cellulose biosynthesis will be investigated by utilising microarray and co-expression data to identify novel genes that are highly co-regulated with the cellulose biosynthetic CesA genes during tension wood formation of hybrid aspen. Arabidopsis mutants in some of these genes have revealed interesting cell wall phenotypes, suggesting that they are important parts of cellulose biosynthesis. We will analyse localization and function of these genes in Arabidopsis. We will also modify expression levels of some these genes in transgenic hybrid aspen trees for functional analysis in cellulose biosynthesis and related processes. In addition to the analysis of wood chemistry and saccharification potential, the novel lines will be analysed for the structure of cellulose and for mechanical analysis (3.5.2) in collaboration with Dr. Ingo Burgert.
Supervisor: Björn Sundberg (
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Improving biomass production in trees –modification of the wood density |
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The aim of this PhD project is to improve biomass accumulation in the stem by controlling the lifetime of the individual xylem elements. The idea is to prolong the lifetime of the xylem elements in order to prolong the phase of wood cell wall deposition, which is then expected to result in increased wood density and therefore also increased biomass accumulation in the stem. In this project, cell death is modified in transgenic Populus trees by modifying expression pattern of a recently identified protein which regulates the interplay between lignification and cell death, followed by analysis of wood properties and saccharification potential. The function of this protein is also further characterised in the herbaceous woody model system Arabidopsis thaliana by using modern molecular, genetic and biochemical tools.
Supervisor: Hannele Tuominen (
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PhD Student: Sacha Escamez |
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Recalcitrance of the lignocellulose – focus on cell wall acetylation |
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The PhD project aims at elucidation of xylan-lignin interactions in cell walls that are mediated by xylan acetylation. Xylan and lignin are most important repositories of carbon within the terrestial biomass, and major determinants of lignocellulose conversion to biofuels. Xylan and lignin are known to interact in cell wall however, the structural basis of these interactions are not well understood. The knowledge of these interactions will let us design better methods for lignocellulose utilization. In particular, we will be better equipped to design pretreatment conditions for separation of lignin, hemicellulose and cellulose. The xylan acetylation will be modified in model plant species, hybrid aspen and Arabidopsis thaliana using either native biosynthetic genes or genes of wood-degrading fungi. Effects of these modifications on cell wall organization and on lignocellulose properties will be assessed with an array of biochemical, spectroscopy- and microscopy- based approaches.
Supervisor: Ewa Mellerowicz (
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PhD Student: Prashant Mohan Pawar |
Ogonna Obudulu
In this PhD project, selected hybrid aspen trees will be analysed for their metabolome and proteome utilizing recently established UPSC platforms (http://www.upsc.se/metabolomics-facility, www.chem.umu.se/upa). Wood samples will be collected from the stem, and analysed with the help of the personnel employed by facility. The PhD student will be involved in integration of the metabolomic and proteomic data using multivariate methods, such as O2PLS (bidirectional orthogonal projections to latent structures) that have been developed at UPSC. Furthermore, co-expression network analysis will be performed, which will provide a systems biology platform for experimental tree biology that will have a profound effect on e.g. experimental planning and the ability to seek underlying molecular explanations for phenotypic data.
Supervisor: Gunnar Wingsle (
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PhD Student:
Ogonna Obudulu |
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Bioprocessing properties in Populus wood |
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Venkata SoudhamIn this PhD project, selected hybrid aspen lines will be evaluated with regard to chemical properties and processability. Wood samples will be pretreated and the susceptibility of the pretreated lignocellulose to enzymatic hydrolysis will be investigated. The studies will include novel approaches to pretreat lignocellulosic feedstocks. Factors that govern the recalcitrance of lignocellulose to pretreatment and enzymatic conversion processes will be investigated. The chemical composition and the fermentability of the resulting hydrolysate will be studied as well as the properties of the lignin-rich residue obtained after enzymatic hydrolysis. Multivariate data analysis will be employed to study differences between the investigated lines, the chemical composition of the various fractions, and the processability. The evaluation process will offer information about conversion of the feedstock not only for the production of cellulosic ethanol, but also for other biofuels and chemicals. The work will in part be performed in laboratories in Örnsköldsvik and in collaboration with regional biorefinery companies, such as Processum Biorefinery Initiative, MoRe Research, SEKAB E-Technology, and Domsjö Fabriker.
Supervisor: Leif Jönsson (
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PhD Student: Venkata Soudham |
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Research 
