Microtubule rearrangements accompanying dedifferentiation in mesophyll cultures ofZinnia elegans L.

Summary To determine the orientation of cortical microtubule arrays in mesophyll cells ofZinnia, a new technique designed to increase the rate of fixation of excised leaf tissue and subsequent permeabilization of mesophyll cell walls was developed. This procedure resulted in immunolabeling of high percentages of mesophyll cells, making it possible to quantify cells with different types of cortical microtubule arrays. When developing palisade mesophyll cells were fixed in situ, most of the cells had cortical microtubules organized in parallel arrays oriented transverse to the long axis. Delay in the transfer of leaf tissue to fixative resulted in increased numbers of cells with random cortical microtubule orientations, indicating that arrays may become reoriented rapidly during leaf excision and cell isolation procedures. The role of wound-induced microtubule reorientation in mesophyll dedifferentiation and tracheary element development is discussed.Abbreviations BSA bovine serum albumin - CMT cortical microtubule - TE tracheary element - TBS tris-buffered saline