The co-localization and possible interactions of integrin-like protein and alpha-tubulin in the root cells of Zea mays.

Plant cell wall-plasma membrane-cytoskeleton (CW-PM-CSK) continuum plays important roles in the regulation of plant responses to environmental cues. It has been found in our previous study that an integrin-like protein identified in Arabidopsis and Zea mays plasma membrane mediates the interactions between cell wall and plasma membrane and cell responses to osmotic stress. In the present study, the co-localization of integrin-like protein and alpha-tubulin and their possible interactions were investigated in the root cells of maize using an indirect immunofluorescence technique combined with pharmacological approach. As compared with the control, after treatment with GRGDS, a synthetic peptide contained the RGD domain which binds specifically to integrin-like protein, the integrin-like protein was distributed more evenly over the plasma membrane and the density of alpha-tubulin array became lower. However, treatment with SDGRG, a GRGDS analog which does not contain the RGD domain, had no influences on them. Microtubule-depolymering or -stabilizing reagents exerted their effects either on the distribution over the plasma membrane or on the expression of integrin-like protein. The above results showed that the distribution of integrin-like protein on plasma membrane was closely linked to the alignment of microtubule arrays. Integrin-like protein mediates the interaction between cell wall and plasma membrane, and this interaction in return affected the alignment of microtubule arrays. Changes in cytoskeleton dynamics had significant effect on the distribution of integrin-like protein on the plasma membrane. These results strongly suggest that there are interactions between integrin-like protein and cytoskeleton in plant cells which are very complicated. It is worthy of extensive study to work out the mechanisms of plant responses to intracellular and extracellular signals.