Plasma membrane-associated SCAR complex subunits promote cortical F-actin accumulation and normal growth characteristics in arabidopsis roots

Julia Dyachok, Mon Ray Shao, Kevin Vaughn, Andrew Bowling, Michelle Facette, Stevan Djakovic, Lauren Clark, Laurie Smith

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

The ARP2/3 complex, a highly conserved nucleator of F-actin polymerization, and its activator, the SCAR complex, have been shown to play important roles in leaf epidermal cell morphogenesis in Arabidopsis. However, the intracellular site(s) and function(s) of SCAR and ARP2/3 complex-dependent actin polymerization in plant cells remain unclear. We demonstrate that putative SCAR complex subunits BRK1 and SCAR1 are localized to the plasma membrane at sites of cell growth and wall deposition in expanding cells of leaves and roots. BRK1 localization is SCAR-dependent, providing further evidence of an association between these proteins in vivo. Consistent with plasma membrane localization of SCAR complex subunits, cortical F-actin accumulation in root tip cells is reduced in brk1 mutants. Moreover, mutations disrupting the SCAR or ARP2/3 complex reduce the growth rate of roots and their ability to penetrate semi-solid medium, suggesting reduced rigidity. Cell walls of mutant roots exhibit abnormal structure and composition at intercellular junctions where BRK1 and SCAR1 are enriched in the adjacent plasma membrane. Taken together, our results suggest that SCAR and ARP2/3 complex-dependent actin polymerization promotes processes at the plasma membrane that are important for normal growth and wall assembly.

Original languageEnglish (US)
Pages (from-to)990-1006
Number of pages17
JournalMolecular Plant
Volume1
Issue number6
DOIs
StatePublished - Nov 2008

Keywords

  • Arabidopsis
  • Cell expansion
  • Cell morphogenesis
  • Cytoskeleton
  • Root biology

ASJC Scopus subject areas

  • Molecular Biology
  • Plant Science

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    Dyachok, J., Shao, M. R., Vaughn, K., Bowling, A., Facette, M., Djakovic, S., Clark, L., & Smith, L. (2008). Plasma membrane-associated SCAR complex subunits promote cortical F-actin accumulation and normal growth characteristics in arabidopsis roots. Molecular Plant, 1(6), 990-1006. https://doi.org/10.1093/mp/ssn059