Adaptor protein complex 2-mediated endocytosis is crucial for male reproductive organ development in Arabidopsis

Plant Cell. 2013 Aug;25(8):2970-85. doi: 10.1105/tpc.113.114264. Epub 2013 Aug 23.


Fertilization in flowering plants requires the temporal and spatial coordination of many developmental processes, including pollen production, anther dehiscence, ovule production, and pollen tube elongation. However, it remains elusive as to how this coordination occurs during reproduction. Here, we present evidence that endocytosis, involving heterotetrameric adaptor protein complex 2 (AP-2), plays a crucial role in fertilization. An Arabidopsis thaliana mutant ap2m displays multiple defects in pollen production and viability, as well as elongation of staminal filaments and pollen tubes, all of which are pivotal processes needed for fertilization. Of these abnormalities, the defects in elongation of staminal filaments and pollen tubes were partially rescued by exogenous auxin. Moreover, DR5rev:GFP (for green fluorescent protein) expression was greatly reduced in filaments and anthers in ap2m mutant plants. At the cellular level, ap2m mutants displayed defects in both endocytosis of N-(3-triethylammonium-propyl)-4-(4-diethylaminophenylhexatrienyl) pyridinium dibromide, a lypophilic dye used as an endocytosis marker, and polar localization of auxin-efflux carrier PIN FORMED2 (PIN2) in the stamen filaments. Moreover, these defects were phenocopied by treatment with Tyrphostin A23, an inhibitor of endocytosis. Based on these results, we propose that AP-2-dependent endocytosis plays a crucial role in coordinating the multiple developmental aspects of male reproductive organs by modulating cellular auxin level through the regulation of the amount and polarity of PINs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Protein Complex 2 / metabolism*
  • Arabidopsis / cytology
  • Arabidopsis / drug effects
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Clathrin / metabolism
  • Cytosol / drug effects
  • Cytosol / metabolism
  • Endocytosis* / drug effects
  • Fertilization / drug effects
  • Germination / drug effects
  • Green Fluorescent Proteins / metabolism
  • Indoleacetic Acids / pharmacology
  • Mutation / genetics
  • Pollen / cytology
  • Pollen / drug effects
  • Pollen / growth & development*
  • Pollen / metabolism
  • Pollen Tube / drug effects
  • Pollen Tube / growth & development
  • Pollen Tube / metabolism
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • Seeds / drug effects
  • Seeds / growth & development
  • Seeds / metabolism


  • Adaptor Protein Complex 2
  • Arabidopsis Proteins
  • Clathrin
  • Indoleacetic Acids
  • PIN2 protein, Arabidopsis
  • Green Fluorescent Proteins