TOR dynamically regulates plant cell-cell transport

Proc Natl Acad Sci U S A. 2020 Mar 3;117(9):5049-5058. doi: 10.1073/pnas.1919196117. Epub 2020 Feb 12.


The coordinated redistribution of sugars from mature "source" leaves to developing "sink" leaves requires tight regulation of sugar transport between cells via plasmodesmata (PD). Although fundamental to plant physiology, the mechanisms that control PD transport and thereby support development of new leaves have remained elusive. From a forward genetic screen for altered PD transport, we discovered that the conserved eukaryotic glucose-TOR (TARGET OF RAPAMYCIN) metabolic signaling network restricts PD transport in leaves. Genetic approaches and chemical or physiological treatments to either promote or disrupt TOR activity demonstrate that glucose-activated TOR decreases PD transport in leaves. We further found that TOR is significantly more active in mature leaves photosynthesizing excess sugars than in young, growing leaves, and that this increase in TOR activity correlates with decreased rates of PD transport. We conclude that leaf cells regulate PD trafficking in response to changing carbohydrate availability monitored by the TOR pathway.

Keywords: Reptin; TARGET OF RAPAMYCIN; cell–cell signaling; plasmodesmata; rapamycin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / embryology
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Biological Transport
  • Carbohydrate Metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • Gene Knockdown Techniques
  • Gene Silencing
  • Nicotiana / genetics
  • Nicotiana / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Plant Cells / metabolism*
  • Plant Leaves / growth & development
  • Plant Leaves / metabolism*
  • Plasmodesmata / metabolism*
  • Protein Transport
  • Signal Transduction


  • Arabidopsis Proteins
  • TOR protein, Arabidopsis