SCAR mediates light-induced root elongation in Arabidopsis through photoreceptors and proteasomes

Julia Dyachok, Ling Zhu, Fuqi Liao, Ji He, Enamul Huq, Elison B. Blancaflor

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


The ARP2/3 complex, a highly conserved nucleator of F-actin, and its activator, the SCAR complex, are essential for growth in plants and animals. In this article, we present a pathway through which roots of Arabidopsis thaliana directly perceive light to promote their elongation. The ARP2/3-SCAR complex and the maintenance of longitudinally aligned F-actin arrays are crucial components of this pathway. The involvement of the ARP2/3-SCAR complex in light-regulated root growth is supported by our finding that mutants of the SCAR complex subunit BRK1/HSPC300, or other individual subunits of the ARP2/3-SCAR complex, showed a dramatic inhibition of root elongation in the light, which mirrored reduced growth of wildtype roots in the dark. SCAR1 degradation in dark-grown wild-type roots by constitutive photomorphogenic 1 (COP1) E3 ligase and 26S proteasome accompanied the loss of longitudinal F-actin and reduced root growth. Light perceived by the root photoreceptors, cryptochrome and phytochrome, suppressed COP1-mediated SCAR1 degradation. Taken together, our data provide a biochemical explanation for light-induced promotion of root elongation by the ARP2/3-SCAR complex.

Original languageEnglish (US)
Pages (from-to)3610-3626
Number of pages17
JournalPlant Cell
Issue number10
StatePublished - Dec 2011

ASJC Scopus subject areas

  • Plant Science
  • Cell Biology


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