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.