Influence of the cell wall on the organisation and dynamics of intracellular components in Arabidopsis Thaliana
This study used live cell imaging of fluorescently labelled marker proteins to quantify the organisation and dynamics of the actin cytoskeleton and to determine if and how it was affected when the connection between the cell wall and plasma membrane was disturbed. Two image analysis techniques were developed to measure the dynamic remodelling of the actin cytoskeleton: Pairwise image subtraction and Cumulative fluorescence intensity. Both these analysis techniques showed that the actin cytoskeleton had a decreased rate of bulk remodelling when the cell wall-plasma membrane-actin continuum was disrupted either by plasmolysis or with isoxaben, a drug that specifically inhibits cellulose deposition. Changes in the rate of actin remodelling also affected its functionality as observed by alteration in Golgi body motility. The possibility that the changes seen were part of a general abiotic stress response by the actin cytoskeleton was refuted by showing that temperature stress did not decrease the rate of bulk remodelling. The effect of complete cell wall removal on the actin cytoskeleton was also investigated, but there was little difference in bulk remodelling between protoplasts immediately post-cell wall removal and after 24 h of cell wall re-growth. In addition to actin cytoskeleton remodelling, this study also aimed to discover if plasma membrane protein mobility was altered in cells with a perturbed cell wall. It is known that the mobility of plasma membrane proteins can be increased in plant cells that have had their cell wall removed or separated from the plasma membrane. In this study, cell wall perturbations were caused by mutations leading to a lack of detectable xyloglucan. Some of the plasma membrane proteins examined had altered mobility in cells with a disturbed cell wall, but others did not, suggesting different components in the cell wall affect specific plasma membrane associations. Together these results show that disturbing the cell wall-plasma membrane interface reduces the dynamic remodelling of the actin cytoskeleton and affects plasma membrane protein mobility.
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