A basic helix-loop-helix transcription factor controls cell growth and size in root hairs.
Postmitotic cell growth defines cell shape and size during development. However, the mechanisms regulating postmitotic cell growth in plants remain unknown. Here we report the discovery of a basic helix-loop-helix (bHLH) transcription factor called RSL4 (ROOT HAIR DEFECTIVE 6-LIKE 4) that is sufficient to promote postmitotic cell growth in Arabidopsis thaliana root-hair cells. Loss of RSL4 function resulted in the development of very short root hairs. In contrast, constitutive RSL4 expression programmed constitutive growth, resulting in the formation of very long root hairs. Hair-cell growth signals, such as auxin and low phosphate availability, modulate hair cell extension by regulating RSL4 transcript and protein levels. RSL4 is thus a regulator of growth that integrates endogenous developmental and exogenous environmental signals that together control postmitotic growth in root hairs. The control of postmitotic growth by transcription factors may represent a general mechanism for regulating cell size across diverse organisms.
Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom.
Keke
K
Yi
Benoît
B
Menand
Elizabeth
E
Bell
Liam
L
Dolan
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000502:physiology*; D049109:Cell Proliferation; D048429:Cell Size; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D003513:Cycloheximide; D003907:Dexamethasone; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011500:Protein Synthesis Inhibitors; C548371:RSL4 protein, Arabidopsis