Abstract
Plant roots perceive the hardness of soil. However, it remained unclear whether they perceive the pore size of soil. To investigate the effects of soil-pore size on root behavior, we have designed a novel bioassay.
Various sizes of nylon mesh were suspended on plastic supports in petri dishes and phytagel was added, embedding the mesh in the middle of the culture medium. Four days after Arabidopsis seeds were sown on the surface of medium, root behavior was observed.
When the roots reached the mesh, they exhibited one of 3 behaviors (bending, coiling and passing). Roots bent upon reaching mesh with sizes below 42 μm. On the other hand, they passed through the mesh with sizes greater than 95 μm, which is the mean diameter of the boundary between the root cap and elongation zone. This suggests that the root cap is involved in determining root behavior to mesh pore size.
