Plant Cell Walls - Class Integrin - Cytoskeleton Continuum In Plant Responses To Osmotic Stress Signal Process

To explore the mechanisms of how plants response to environmental stresses and thus to improve the resistance of plants to environmental stresses is very important both for the theoretic study and for the practical applications. In this study, the suspension cell lines of Arabidopsis Thaliana and the root tips of Zea Mays L were used as experimental materials to investigate the roles of cell wall-plasma membrane-cytoskeleton continuum in the responses of plant cells to osmotic stress. The main results obtained are summarized as follows:1. Western blotting and immuno-fluorescent localization studies, using a monoclonal antibody against (31 subunit of rabbit integrin, showed that the integrin-like protein localized in the plasma membrane fraction in Arabidopsis suspension cells and both cell membrane and nucleus of maize root cells with a molecular weight of ca.100 kDa and 80 kDa for Arabidopsis suspension cells and maize root cells, respectively.2. Under normal conditions (non-osmotic stress), the cell wall and plasma membrane was adhered together around the cells. However, the cell wall and plasma membrane was separated (plasmolyzed) partially when cells were exposed to osmotic stress. When cells were pretreated with RGD, a three peptide that blocks the link between cell wall and plasma membrane by binding specially to integrin protein, the cell wall-plasma membrane adhesion of osmotic stressed cells was not observed, suggesting that the integrin-like protein involved in the cell wall-plasma membrane adhesion.3. Under an osmotic stress condition, the ABA content of cells and protoplasts increased significantly, as compared with that of controlled cells and protoplasts (non stressed). However, the increase in ABA content of stressed protoplasts (1.7-fold higher than that of control) was much lower than that of stressed cells (2.3-fold higher than that of controlled cells). RGD treatment obviously inhibited the osmotic stress-induced ABA biosynthesis. These results implied that cell wall itself and/or the interaction between...