Lignin for dynamic adaptability of Plant Biomechanics to climate changes

Climate models predict more drastic changes for Scandinavian countries with dryer summer and warmer, rainier winter climates and more frequent short but extreme weather events. Crops and forest flora will face a combination of drought stresses, water logging and mechanical stresses such as wind due to extreme weather events throughout the seasons. The plant vascular system, that both transports water and provides skeletal support, is the primary element to counter climate related stresses. Drought and waterlogging will thus strain hydraulic and biomechanics capabilities of plant vasculature in order to resist lodging and/or mechanical failure due to external forces while maintaining normal hydration and oxygenation. A key element to adjust vascular tissues to hydraulic and mechanical constraints is lignin, polyphenolic cell wall polymers that impregnate each vascular cell with different chemistry in plants. Lignin represents around 30% of the carbon in the entire biosphere and regroups a multitude of aromatic polymers with different water-repelling and/or biomechanical properties depending on their biochemical composition. Lignin forms a complex multi-branched structure of linked C6C3 phenylpropanoids that differ in both their C6 and C3 chemistry. Lignin chemistry specifically changes in each cell types in response to developmental and/or environmental constraints throughout the plant life. The exact function of each unit in the lignin “chemical code” still remains unclear, although recently the host team demonstrated the functional difference between two units with similar C6 but distinct C3 chemistry. To further decipher the lignin code, the herein project aims to define the link between plant cell specific lignin chemistries altered by genetic modifications, plant vascular tissue organisation and the biomechanical properties to resist/recover from various climate changes (drought, waterlogging or high wind). Determining these relationships will establish key insights into the biomechanical convergence and/or divergence that lignin chemistry provide to different plant species to grow and cope with climate change challenges.

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• Anatomical limitations in adventitious root formation revealed by magnetic resonance imaging, infrared spectroscopy, and histology of rose genotypes with contrasting rooting phenotypes 

  2024. David Wamhoff (et al.). Journal of Experimental Botany

  Artikel

  Adventitious root (AR) formation is one of the most important developmental processes in vegetative propagation. Although genotypic differences in rose rooting ability are well known, the causal factors are not well understood. The rooting of two contrasting genotypes, ‘Herzogin Friederike’ and ‘Mariatheresia’, was compared following a multiscale approach. Using magnetic resonance imaging, we non-invasively monitored the inner structure of stem cuttings during initiation and progression of AR formation for the first time. Spatially resolved Fourier-transform infrared spectroscopy characterized the chemical composition of the tissues involved in AR formation. The results were validated through light microscopy and complemented by immunolabelling. The outcome demonstrated similarity of both genotypes in root primordia formation, which did not result in root protrusion through the shoot cortex in the difficult-to-root genotype ‘Mariatheresia’. The biochemical composition of the contrasting genotypes highlighted main differences in cell wall-associated components. Further spectroscopic analysis of 15 contrasting rose genotypes confirmed the biochemical differences between easy- and difficult-to-root groups. Collectively, our data indicate that it is not the lack of root primordia limiting AR formation in these rose genotypes, but the firmness of the outer stem tissue and/or cell wall modifications that pose a mechanical barrier and prevent root extension and protrusion. 

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