Gravity signal transduction in primary roots.
OBJECTIVE
The molecular mechanisms that correlate with gravity perception and signal transduction in the tip of angiosperm primary roots are discussed.


METHODS
Gravity provides a cue for downward orientation of plant roots, allowing anchorage of the plant and uptake of the water and nutrients needed for growth and development. Root gravitropism involves a succession of physiological steps: gravity perception and signal transduction (mainly mediated by the columella cells of the root cap); signal transmission to the elongation zone; and curvature response. Interesting new insights into gravity perception and signal transduction within the root tip have accumulated recently by use of a wide range of experimental approaches in physiology, biochemistry, genetics, genomics, proteomics and cell biology. The data suggest a network of signal transduction pathways leading to a lateral redistribution of auxin across the root cap and a possible involvement of cytokinin in initial phases of gravicurvature.


CONCLUSIONS
These new discoveries illustrate the complexity of a highly redundant gravity-signalling process in roots, and help to elucidate the global mechanisms that govern auxin transport and morphogenetic regulation in roots.
Perrin
Robyn M
RM
Laboratory of Genetics, University of Wisconsin-Madison, 425-G Henry Mall, Madison, WI 53706, USA.
Young
Li-Sen
LS
Murthy U M
Narayana
N
Harrison
Benjamin R
BR
Wang
Yan
Y
Will
Jessica L
JL
Masson
Patrick H
PH
D018522:Gravitropism / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology; D010937:Plant Growth Regulators / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
D007473:Ion Channels; D010937:Plant Growth Regulators; D010940:Plant Proteins