Cell wall heterogeneity during root growth

• Applicant: Dr. Marc Somssich
• Subject Area: Plant Cell and Developmental Biology ; Plant Genetics and Genomics ; Plant Physiology
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 344523413

A defining feature of plant cells are their walls. Plant cell walls largely consist of polysaccharides, including cellulose, hemicelluloses and pectins; however, the exact composition of the cell walls may differ depending on type and the developmental state of the cells. Nevertheless, a detailed chart of the cell wall patterning across cell types and root development, and the function of these walls for individual cells is largely lacking. The root with its different developmental zones and specialized differentiated cells offers a suitable model to analyze these differences.To create such a chart, I will first establish a root cell wall map using over 200 available antibodies recognizing specific bonds and sugars in the wall. Labeling of root sections with these antibodies will reveal regional differences in cell wall composition and visualize transition zones, intermediate states and changes caused by differentiation events. These data will then be combined with available transcriptomic and translatomic datasets of specific root cell types to infer relationships between wall epitopes, expressed genes and synthesized proteins with relevance to root development. To analyze how these local wall differences are created, I will then monitor xyloglucan endotransglycosylase/hydrolase (XTH) enzyme activity. XTH-dependent wall-integration of labeled xyloglucan polysaccharides will be monitored using time-lapse and super-resolution microscopy providing spatio-temporal information about localized cell wall modifications in different developmental root zones and on individual cell level. This will then be combined with transcriptional and translational reporter lines for the different XTH enzymes. Finally, I will perturb cell wall modification by the use of higher-order XTH mutants to link the function of individual enzymes to specific root domains and developmental zones, or other pathways involving the diurnal cycle or phytohormones. The resulting virtual root will serve as an important resource to better understand root growth and function.

• DFG Programme: Research Fellowships
• International Connection: Australia
• Host: Professor Dr. Staffan Persson