Acrylamide inhibits gravitropism and affects microtubules in rice coleoptiles

To find components which participate in gravitropic signal transmission, we screened different cell biological inhibitors for their effect on gravitropic bending of rice coleoptiles. Acrylamide, which is known to affect intermediate filaments in mammalian cells, strongly inhibited gravitropic bending at concentrations that did not inhibit growth of coleoptile segments. This inhibition was reversible. Investigating the acrylamide effect further, we found that it interferes with an event that occurs around 15 min after the onset of stimulation. We also observed that acrylamide inhibits polar indolyl-3-acetic acid transport. Furthermore, acrylamide efficiently eliminated microtubules, whereas actin filaments remained intact. To our knowledge this is the first report of effects of monoacrylamide in plant cells.