Root hair-specific expansins modulate root hair elongation in rice

Plant J. 2011 Jun;66(5):725-34. doi: 10.1111/j.1365-313X.2011.04533.x. Epub 2011 Mar 21.


Root hair growth requires intensive cell-wall modification. This study demonstrates that root hair-specific expansin As, a sub-clade of the cell wall-loosening expansin proteins, are required for root hair elongation in rice (Oryza sativa L.). We identified a gene encoding EXPA17 (OsEXPA17) from a rice mutant with short root hairs. Promoter::reporter transgenic lines exhibited exclusive OsEXPA17 expression in root hair cells. The OsEXPA17 mutant protein (OsexpA17) contained a point mutation, causing a change in the amino acid sequence (Gly104→Arg). This amino acid alteration is predicted to disrupt a highly conserved disulfide bond in the mutant. Suppression of OsEXPA17 by RNA interference further confirmed requirement for the gene in root hair elongation. Complementation of the OsEXPA17 mutant with other root hair EXPAs (OsEXPA30 and Arabidopsis EXPA7) can restore root hair elongation, indicating functional conservation of these root hair EXPAs in monocots and dicots. These results demonstrate that members of the root hair EXPA sub-clade play a crucial role in root hair cell elongation in Graminaceae.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Cell Enlargement
  • Cloning, Molecular
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • Genetic Complementation Test
  • Genetic Vectors
  • Oryza / genetics
  • Oryza / growth & development*
  • Oryza / metabolism
  • Plant Proteins / metabolism*
  • Plant Roots / genetics
  • Plant Roots / growth & development*
  • Plant Roots / metabolism
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism
  • Point Mutation
  • Protein Structure, Tertiary
  • RNA Interference


  • Arabidopsis Proteins
  • Plant Proteins
  • expansin protein, plant