Gravitropism in the Salt-Stressed Primary Root of Maize (Zea mays)

We investigated gravitropic responses in the primary root of maize (Zea mays) seedlings which were exposed to salt stress. The maize roots salt-stressed with higher than 100 mM NaCl or KCl started to reveal enhanced gravitropic curvature after 2 hours form the gravi-stimulation. Such a promotion was not caused by sodium phosphate, but invoked by potassium phosphate, indicating the active component is . Because NaCl increased gravitropic curvature, despite that did not played any role, we evaluated the role for by comparing the effects of and . The enhancement of the curvature only with revealed that played a role in the gravi-response, indicating the involvement of anion channels. These results suggest that both of and play roles in the regulation of osmosis that is required for cell expansion in gravitropism as well as in nyctinasty and stomatal opening.