The plasmodesmatal transport pathway for homeotic proteins, silencing signals and viruses

Curr Opin Plant Biol. 2004 Dec;7(6):641-50. doi: 10.1016/j.pbi.2004.09.012.


Non-cell-autonomous signals in the form of microRNAs and transcription factors could have important developmental functions. Plasmodesmata (PD) form a cytoplasmic network throughout the plant body and provide the means of symplasmic cell-to-cell transport in plants. Homeodomain transcription factors, small RNA molecules and viral genomic information move selectively to adjacent cells via PD microchannels. Tissue-specific expression studies of non-cell-autonomous transcription factors and RNA molecules have confirmed that their intercellular transport is a highly regulated process, which depends on the tissue, developmental stage and nature of the transported macromolecule. We have known for some time that gene-silencing signals spread both locally from cell to cell and across long distances following the source to sink transition. Recent work has provided evidence that small single-stranded silencing-induced RNAs and microRNA molecules are present in the phloem transport system of different plant species. Further, recent evidence has confirmed that the transport of silencing RNA via PD is a regulated and active process, and that an amplification-relay mechanism is in place for the long-distance spread of silencing signals.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biological Transport*
  • Homeodomain Proteins / metabolism*
  • Models, Biological
  • Plants / metabolism*
  • Plasmodesmata / metabolism*
  • RNA Interference
  • RNA, Plant / metabolism
  • RNA-Binding Proteins / metabolism
  • Signal Transduction


  • Homeodomain Proteins
  • RNA, Plant
  • RNA-Binding Proteins