The Arabidopsis Athb-10 (GLABRA2) is an HD-Zip protein required for regulation of root hair development

Plant J. 1996 Sep;10(3):393-402. doi: 10.1046/j.1365-313x.1996.10030393.x.


Homeodomain-leucine zipper (HD-Zip) proteins are putative transcription factors identified only in plants. Related Arabidopsis homeobox genes, isolated by virtue of sequence conservation within the helix-3 region of the homeodomain, fall into four families based on sequence similarity. This paper reports the characterization of Athb-10, a 747 amino acid protein belonging to the fourth HD-ZIP family. The studies indicate that, although less conserved, the leucine zipper of Athb-10 can functionally replace that of Athb-2 in an in vitro DNA-binding assay. Gene mapping experiments and sequence comparison analysis revealed that Athb-10 corresponds to GLABRA2, a homeodomain protein involved in trichome development. The mRNA expression analysis revealed that Athb-10/GLABRA2 is expressed not only in trichome-bearing organs, but also in the root. The analysis of wild-type and mutant plants showed that the Athb-10/GLABRA2 gene expression in the aerial part of the plant and in the root is affected by mutations at the TTG locus. Morphological analysis of the g/2-1 mutant revealed that the gene is necessary not only for local outgrowth of the trichome, but also for the regulation of root hair development in a subset of epidermal cells. Interestingly, the development of root hair cells in a position normally occupied by non-hair cells is dependent upon the ethylene regime in which the gl2-1 plants are grown. Sequence analysis of the gl2-1 allele revealed that the mutant gene encodes a truncated protein that might still retain a partial activity responsible for the formation of aborted trichomes and for the ethylene-dependent regulation of root hair formation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins*
  • Ethylenes / pharmacology
  • Gene Expression Regulation, Plant / genetics
  • Genes, Plant / genetics*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Homeodomain Proteins / physiology
  • Leucine Zippers
  • Molecular Sequence Data
  • Mutation
  • Plant Growth Regulators / pharmacology
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Proteins / physiology
  • Plant Roots / growth & development*
  • RNA, Messenger / analysis
  • RNA, Plant / analysis
  • Recombinant Fusion Proteins / metabolism
  • Sequence Analysis, DNA


  • Arabidopsis Proteins
  • Ethylenes
  • GL2 protein, Arabidopsis
  • Homeodomain Proteins
  • Plant Growth Regulators
  • Plant Proteins
  • RNA, Messenger
  • RNA, Plant
  • Recombinant Fusion Proteins
  • ethylene

Associated data

  • GENBANK/Z54356