The Roles Of Integrin-like Proteins And Tubulin In The Responses Of Plants To Osmotic Stress

Adverse environmental factors, such drought, salinity, extreme temperature, etc, have deleterious effects on plant growth and development, thus the final plant productivity. It is understandable that, when plants are imposed to drought stress, the cell wall and/or plasma membrane are the most possible candidates for the primary sensing site(s). In plants, much progress has been made in understanding the complexity of the cell wall chemistry and cell wall extension, but there is still little information concerning its dynamic nature and interaction between it and the plasma membrane. Over the past two decades, evidence has been accumulated that the plant cell wall may interact with many proteins of the plasma membrane, like the extracellular matrix (ECM) in animals, and these in turn may interact directly or indirectly with the cytoskeleton. Integrin is one of the most important plasma membrane proteins in animals, which interacts with ECM and cytoskeleton and plays important roles in many physiological processes. In present study, several techniques, including immunological, biochemical and molecular biological techniques, have been used to explore whether there existed a similar molecule in plasma membrane, like integrin in animals, and if so, its possible interaction with cell wall and cytoskeleton. In addition, what are the roles of cell wall-plasma membrane-cytoskeleton continnum in the responses to osmotic stress? The results indicated that1. Western blotting and immuno-fluorescent localization studies, using a monoclonal antibody againstβ1 subunit of human 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.110 kDa and 80 kDa for Arabidopsis suspension cells and maize roots, 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 treated with RGD, a polypeptide that blocks the link between...