A small, novel protein highly conserved in plants and animals promotes the polarized growth and division of maize leaf epidermal cells

Curr Biol. 2002 May 14;12(10):849-53. doi: 10.1016/s0960-9822(02)00819-9.


Plant cell shapes are defined by their surrounding walls, but microtubules and F-actin both play critical roles in cell morphogenesis by guiding the deposition of wall materials in expanding cells. Leaf epidermal cells have lobed shapes, which are thought to arise through a microtubule-dependent pattern of locally polarized growth. We have isolated a recessive mutation, brk1, which blocks the formation of epidermal cell lobes in the maize leaf. Mutant epidermal cells expand to the same extent as wild-type cells but fail to establish polar growth sites from which lobes arise. In expanding brk1 epidermal cells, microtubule organization differs little from that in wild-type, but localized enrichments of cortical F-actin seen at the tips of emerging lobes in wild-type cells fail to form. These observations suggest a critical role for F-actin in lobe formation and together with additional effects of brk1 on the morphogenesis of stomata and hairs suggest that Brk1 promotes multiple, actin-dependent cell polarization events in the developing leaf epidermis. The Brk1 gene encodes a novel, 8 kD protein that is highly conserved in plants and animals, suggesting that BRK1-related proteins may function in actin-dependent aspects of cell polarization in a wide spectrum of eukaryotic organisms.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actins / metabolism
  • Amino Acid Sequence
  • Animals
  • Cell Division
  • Cell Polarity*
  • Conserved Sequence*
  • Gene Expression Regulation, Plant
  • Genes, Plant / genetics
  • Humans
  • Molecular Sequence Data
  • Plant Epidermis / cytology*
  • Plant Epidermis / genetics
  • Plant Epidermis / metabolism*
  • Plant Leaves* / cytology
  • Plant Leaves* / genetics
  • Plant Leaves* / metabolism
  • Plant Proteins / chemistry*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Sequence Homology, Amino Acid
  • Zea mays* / cytology
  • Zea mays* / genetics
  • Zea mays* / metabolism


  • Actins
  • Plant Proteins
  • RNA, Messenger

Associated data

  • GENBANK/AY093614