Root gravitropism: a complex response to a simple stimulus?
Roots avoid depleting their immediate environment of essential nutrients by continuous growth. Root growth is directed by environmental cues, including gravity. Gravity sensing occurs mainly in the columella cells of the root cap. Upon reorientation within the gravity field, the root-cap amyloplasts sediment, generating a physiological signal that promotes the development of a curvature at the root elongation zones. Recent molecular genetic studies in Arabidopsis have allowed the identification of genes that play important roles in root gravitropism. Among them, the ARG1 gene encodes a DnaJ-like protein involved in gravity signal transduction, whereas the AUX1 and AGR1 genes encode proteins involved in polar auxin transport. These studies have important implications for understanding the intra- and inter-cellular signaling processes that underlie root gravitropism.
Rosen
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Laboratory of Genetics, University of Wisconsin-Madison 53706, USA.
Chen
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Masson
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D017360:Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D017343:Genes, Plant; D018522:Gravitropism / Q000235:genetics* / Q000502:physiology*; D018466:Gravity Sensing / Q000502:physiology; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000502:physiology; D010940:Plant Proteins; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018087:Plastids / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007210:Indoleacetic Acids; D010940:Plant Proteins; C100794:AUX1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis