Dynamical and Microrheological Analysis of Amyloplasts in the Plant Root Gravity-Sensing Cells

Abstract

Gravitropism in plants is one of the most controversial issues. In the most wildly accepted starch-statolith hypothesis the sedimentation movement of amyloplasts in the gravisensing columella cells primarily triggers the asymmetric distribution of auxin which leads to the differential growth of the plant root. It has been gradually recognized that the inhomogeneous structures in statocytes arising from intracellular components such as cytoskeletons significantly affect the complex movements of amyloplasts and the final gravimorphogenesis. In this letter, we implement a diffusive dynamics measurement and inplanta microrheological analysis of amyloplasts in the wild-type plants and actin cytoskeleton mutants for the first time. We found that the intracellular environment of columella cells exhibits the Zhongyu Zheng

Both gravistimulation onset and removal trigger an increase of cytoplasmic free calcium in statocytes of roots grown in microgravity

“…In maize, it decreases from 19.1 µm min −1 to 3.7 µm min −1 , a few seconds to 30 seconds after change of inclination 32 . Statolith sedimentation has been reported to be over after 400 seconds in Arabidopsis roots 33 . Accordingly, the mean difference of 3.2 µm observed between statolith positioning in microgravity and simulated gravity should disappear when microgravity roots are submitted to ten minutes of simulated gravity.…”