Interphase microtubule re-orientation predicts a new cell polarity in wounded pea roots

We have developed a useful infiltration and embedding technique for cryosectioning and immunostaining plant tissues, which allows the examination of microtubule (MT) arrays across large areas of sub-epidermal tissue. Using the wound response as a tool for investigating the processes underlying the establishment of a new cell polarity, we have found that a re-orientation of interphase arrays is initiated between 2 and 5 hours post-wounding. This demonstrates that new cell polarity is established sooner after wounding than was previously thought. This cytoskeletal shift appears to act as a spatial precursor for the subsequent change in growth axis, which is manifested in the cell expansion planes, and positioning of the pre-prophase band (PPB) and new cell walls. We have demonstrated that interphase MT reorientation precedes and predicts new cell polarity in a higher plant tissue. Possible mechanisms important in orchestrating this dramatic developmental change could be electric fields, generated by ionic wound currents, and the alteration of mechanical stress patterns within the wounded tissue.