Physical strain‐mediated microtubule reorientation in the epidermis of gravitropically or phototropically stimulated maize coleoptiles

摘要: During gravitropic and phototropic curvature of the maize coleoptile, cortical microtubules (MTs) adjacent to outer epidermal cell wall assume opposite orientations at two sides organ. Starting from a uniformly random pattern during straight growth in darkness, MTs reorientate perpendicularly organ axis (faster growing) side parallel inner (slower side. As similar reorientations can be induced by increasing or decreasing effective auxin concentration, it has been proposed that these may used as diagnostic test for assessing status cells tropic curvature. This idea was tested determining MT coleoptile intact seedlings which prevented inversed an appropriate mechanical counterforce. Forces just curving gravity light field MTs. strong enough overcompensate stimuli enforcing direction those produced stimulation. These results show surface respond changes tissue strain rather than associated level any other element signal transduction chain between perception asymmetric response. It is act gauges positive feed-back regulatory circle utilized amplification stabilization environmentally elongation growth.