Dynamic reorientation of cortical microtubules, from transverse to longitudinal, in living plant cells

摘要: Abstract The direction in which plant tissue cells expand is reflected the alignment of microtubules cortical array. When and coaligned wall microfibrils are arranged transversely around cell, turgor pressure chaneled into cell elongation. However, various agents (such as wounding, ethylene, abscisic acid) can cause to reorientate by 90 degrees so that they become aligned parallel cell's long axis, allowing lateral expansion instead The mechanism undergo rapid shifts crucial understanding growth control plants, but because current models derived from studies on fixed cells, nothing known about dynamics converting one microtubule another. Cells tend have predominant alignment--transverse, oblique, or longitudinal--but it not established whether each represents a stable independent set only changes rounds complete de- repolymerization, reorientation more continuous process involving movement dynamic microtubules. By microinjecting pea (Pisum sativum) epidermal with rhodamine-conjugated brain tubulin optically sectioning them confocal laser scanning microscopy, we could follow labeled for up 2 hr reorientate. Reorientation does occur depolymerization orientation followed polymerization new array another orientation. Instead, increased numbers discordant nontransverse appear particular locations. Neighboring then adopt alignment, there stage during different alignments coexist before outer tangential face finally adopts uniform steeply oblique/longitudinal configuration. Rapid fluorescence recovery after photobleaching confirms bundles exhibit properties consistent instability. Dynamic offer responses range physiological stimuli.