IRREGULAR TRICHOME BRANCH1 in arabidopsis encodes a plant homolog of the actin-related protein2/3 complex activator Scar/WAVE that regulates actin and microtubule organization

Xiaoguo Zhang, Julia Dyachok, Sujatha Krishnakumar, Laurie G. Smith, David G. Oppenheimer

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

The dynamic actin cytoskeleton is important for a myriad of cellular functions, including intracellular transport, cell division, and cell shape. An important regulator of actin polymerization is the actin-related protein2/3 (Arp2/3) complex, which nucleates the polymerization of new actin filaments. In animals, Scar/WAVE family members activate Arp2/3 complex-dependent actin nucleation through interactions with Abi1, Nap1, PIR121, and HSCP300. Mutations in the Arabidopsis thaliana genes encoding homologs of Arp2/3 complex subunits PIR121 and NAP1 all show distorted trichomes as well as additional epidermal cell expansion defects, suggesting that a Scar/WAVE homolog functions in association with PIR121 and NAP1 to activate the Arp2/3 complex in Arabidopsis. In a screen for trichome branching defects, we isolated a mutant that showed irregularities in trichome branch positioning and expansion. We named this gene IRREGULAR TRICHOME BRANCH1 (ITB1). Positional cloning of the ITB1 gene showed that it encodes SCAR2, an Arabidopsis protein related to Scar/WAVE. Here, we show that itb1 mutants display cell expansion defects similar to those reported for the distorted class of trichome mutants, including disruption of actin and microtubule organization. In addition, we show that the scar homology domain (SHD) of ITB1/SCAR2 is necessary and sufficient for in vitro binding to Arabidopsis BRK1, the plant homolog of HSPC300. Overexpression of the SHD in transgenic plants causes a dominant negative phenotype. Our results extend the evidence that the Scar/WAVE pathway of Arp2/3 complex regulation exists in plants and plays an important role in regulating cell expansion.

Original languageEnglish (US)
Pages (from-to)2314-2326
Number of pages13
JournalPlant Cell
Volume17
Issue number8
DOIs
StatePublished - 2005

Fingerprint

Trichomes
Arabidopsis
Microtubules
microtubules
Cicatrix
actin
Actins
trichomes
microfilaments
sequence homology
Actin Cytoskeleton
Polymerization
polymerization
mutants
Defects
cells
Genes
genes
Cell Shape
Genetically Modified Plants

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

IRREGULAR TRICHOME BRANCH1 in arabidopsis encodes a plant homolog of the actin-related protein2/3 complex activator Scar/WAVE that regulates actin and microtubule organization. / Zhang, Xiaoguo; Dyachok, Julia; Krishnakumar, Sujatha; Smith, Laurie G.; Oppenheimer, David G.

In: Plant Cell, Vol. 17, No. 8, 2005, p. 2314-2326.

Research output: Contribution to journalArticle

Zhang, Xiaoguo ; Dyachok, Julia ; Krishnakumar, Sujatha ; Smith, Laurie G. ; Oppenheimer, David G. / IRREGULAR TRICHOME BRANCH1 in arabidopsis encodes a plant homolog of the actin-related protein2/3 complex activator Scar/WAVE that regulates actin and microtubule organization. In: Plant Cell. 2005 ; Vol. 17, No. 8. pp. 2314-2326.
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