Short description
(English)
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The aim of our research is to discover how plants form wood, in particular when they are exposed to mechanical stimuli, such as wind and mechanical loads, using a genomic approach combined with biochemical and histological methods. Wood is generated by the meristematic tissue cambium during xylem differentiation and secondary cell wall formation. In this process, lignins are incorporated into the cell wall composed of cellulose microfibrils, hemicellulose and pectins. The formation of wood and its chemical and physical properties vary during different growth seasons and are influenced by external factors, such as wind, light and temperature. For instance, reaction wood forms, when a stem or branch is displaced from its upright position. Differential growth at the upper and lower side of a stem, coupled with changes in cell wall composition in fibres and tracheids, force it back to its original position, generating wood cells with altered anatomical, physical and chemical properties. In this study we aim to isolate regulators of wood formation. In particular we seek to understand, whether a mechanical force may be a signal for the formation of wood in general and reaction wood in particular. As a model system we use Arabidopsis thaliana, since wood formation has been observed in stems, hypocotyls and roots.
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Partners and International Organizations
(English)
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AT, BE, CH, DE, FI, LU, LV, NL, PL, SE, SI, UK
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Abstract
(English)
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Mechanical interferences of insects or environmental conditions with plants influence their morphology and often lead to ectopic depositions of lignin and callose. For example, bending of tree stems provokes the formation of reaction wood. The goal of our work is to identify the role of mechanical pressure in vascular tissue formation and xylem differentiation. We have developed an experimental set up to apply mild mechanical pressure on growing plants. Inflorescence stems of Arabidopsis thaliana were submitted to compression by centrifuging the plants horizontally at 11 ms-2 with the inflorescence tips pointing to the centre of the centrifuge. The treatment induced secondary growth at the base of inflorescences and slightly changed the amount and composition of lignin monomer and polymers. These changes were not observed, when the treatment was applied to the ethylene insensitive mutant ein2. Our results so far suggest that mechanical signals are involved and that ethylene plays a role in secondary growth regulation. We are currently analysing changes in gene expression profiles upon a short time of mechanical pressure on inflorescences of wild type and ethylene mutant plants, in order to elucidate primary regulators of mechanically induced secondary growth.
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