PRESSURE-INDUCED REORIENTATION OF CORTICAL MICROTUBULES IN EPIDERMAL-CELLS OF LOLIUM-RIGIDUM LEAVES

In order to assess the effect on microtubule arrays of slowly pressuri sing cells over 50 s from 0.1 MPa (atmospheric pressure) to 55 MPa, mi crotubules in epidermal cells of Lolium rigidum leaves were visualised by immunofluorescent staining and fluorescence microscopy. In both co ntrol and pressure-treated leaves cell shape, measured as the ratio of cell length and width, can be correlated to the arrangement of cortic al microtubules. Microtubule arrays change from random to organised in cells whose length is greater than their width. In untreated leaves, elongated cells have microtubules aligned predominantly transversely. In pressure-treated leaves, elongated cells have microtubules aligned predominantly longitudinally. Thus, pressure treatment results in the rapid reorientation of organised cortical microtubules from a transver se to a longitudinal orientation .