Cortical microtubule reorientation in higher plants: Dynamics and regulation

This paper aims to review aspects of cortical microtubule reorientation in higher plant cells. First, we look at the divergent environmental and developmental signals that can elicit the realignment of microtubules in interphase cells. Second, the regulatory factors that might orchestrate microtubule reorientation are examined. In particular, we address the questions of how these extracellular signals are perceived, by what mechanisms this information might be transmitted to the cortical microtubules, and what molecular factors regulate the process of realignment. We put forward an hypothesis of how electric fields reorientate microtubules in plant cells, focusing on the role of transmembrane proteins which might link cortical microtubules in the cytoplasm to the extracellular matrix. Finally, the need to examine microtubule reorientation in live cells is discussed, and we describe the novel visualization of microtubules in live cells of an intact plant. We conclude with our perspective of the future path of research which will be necessary to broaden our understanding of how microtubules undergo rapid reorientation in plant cells.