Poster: Tropisms

Abs # 676: Localization of Amyloplasts in the Distal Elongation Zone of Zea Mays Roots

Presenter:	Stinemetz, Chuck , Stinemetz@Rhodes.edu
Authors	Stinemetz, Chuck  (A)   Keogh, Matthew  (A)   Hoggard, Tim  (A)
Affiliations:	(A): Rhodes College, Department of Biology

Studies have demonstrated that a unique zone of development in roots termed the distal elongation zone plays an important role in the gravitropic response of roots. Recent studies using a “gravity clamp” have suggestd that gravisensing may occur outside of the commonly accepted site of sensing, the root cap, and may in fact take place in the DEZ region. In our TEM and light microscope studies, we found that amyloplasts (the gravisensing statolith) are present in the DEZ region of roots. The amyloplasts are larger than root cap amyloplasts have less starch, and do not clearly sediment in response to gravistimulation. However, this lack of a clear sedimentation pattern, does not rule out the possibility that small displacements of amyloplasts might still allow for a gravisensing mechanism in the DEZ region.