Arabidopsis AIP1-1 regulates the organization of apical actin filaments by promoting their turnover in pollen tubes

Sci China Life Sci. 2020 Feb;63(2):239-250. doi: 10.1007/s11427-019-9532-0. Epub 2019 Jun 25.

Abstract

Apical actin filaments are highly dynamic structures that are crucial for rapid pollen tube growth, but the mechanisms regulating their dynamics and spatial organization remain incompletely understood. We here identify that AtAIP1-1 is important for regulating the turnover and organization of apical actin filaments in pollen tubes. AtAIP1-1 is distributed uniformly in the pollen tube and loss of function of AtAIP1-1 affects the organization of the actin cytoskeleton in the pollen tube. Specifically, actin filaments became disorganized within the apical region of aip1-1 pollen tubes. Consistent with the role of apical actin filaments in spatially restricting vesicles in pollen tubes, the apical region occupied by vesicles becomes enlarged in aip1-1 pollen tubes compared to WT. Using ADF1 as a representative actin-depolymerizing factor, we demonstrate that AtAIP1-1 enhances ADF1-mediated actin depolymerization and filament severing in vitro, although AtAIP1-1 alone does not have an obvious effect on actin assembly and disassembly. The dynamics of apical actin filaments are reduced in aip1-1 pollen tubes compared to WT. Our study suggests that AtAIP1-1 works together with ADF to act as a module in regulating the dynamics of apical actin filaments to facilitate the construction of the unique "apical actin structure" in the pollen tube.

Keywords: ADF; AIP1; actin dynamics; actin turnover; apical actin structure; pollen tube.

MeSH terms

  • Actin Cytoskeleton / genetics*
  • Actin Cytoskeleton / metabolism*
  • Actin Depolymerizing Factors / genetics
  • Actin Depolymerizing Factors / metabolism
  • Actins / metabolism
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Carrier Proteins / metabolism*
  • Cytoskeleton / metabolism
  • Gene Expression Regulation, Plant
  • Pollen Tube / metabolism*
  • Protein Multimerization
  • Recombinant Proteins / metabolism*

Substances

  • ADF1 protein, Arabidopsis
  • AIP1 protein, Arabidopsis
  • Actin Depolymerizing Factors
  • Actins
  • Arabidopsis Proteins
  • Carrier Proteins
  • Recombinant Proteins