Identification and characterization of cell wall integrity monitoring components in plants
Final Report Abstract
Plant cell walls are dynamic structures with important functions during cell expansion, differentiation, structural support and stress responses. When functional integrity is impaired due to cell wall damage (CWD; e.g. caused by cellulose biosynthesis inhibition), specific signaling responses and compensatory reactions are initiated to maintain integrity. We analyzed CWD responses in candidate receptor-like kinases (RLKs) and mechanosensitive channel KO lines and identified those that are essentially required for full CWD response. Interestingly, this group comprises RLKs and mechanosensitive channels localized to the plasma membrane and the plastid envelope. Furthermore, we showed that CWD responses require nitrate reductase function and in part S-nitrosoglutathione reductase function. Genetic and biochemical follow-up studies are performed to better understand the cell wall integrity network organization and regulation. In parallel, we quantified CWD-dependent protein phosphorylation to examine early signaling cascades and identify additional candidate proteins involved in cell wall integrity maintenance. Preliminary data point to regulation of Ca2+ signaling and chloroplast-localized proteins, which is in line with our finding that plastid-localized mechanosensitive channels are required for CWD-dependent hormone accumulation. A screening for transcriptional changes during CWD and in expanding tissues identified a gene potentially involved in membrane trafficking. Sensitivity to CWD is strongly increased in loss-of-function alleles, suggesting it has a regulatory function in cell wall integrity maintenance. By combining the results of the individual project parts we will further our understanding of the mode of action of the mechanism maintaining functional integrity of the cell wall during development and stress exposure.
