Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Root hair curling and Rhizobium infection in Medicago truncatula are mediated by phosphatidylinositide-regulated endocytosis and reactive oxygen species

Smadar Peleg-Grossman, Hanne Volpin and Alex Levine
Journal of Experimental Botany
Vol. 58, No. 7 (2007), pp. 1637-1649
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/24036743
Page Count: 13
  • Download ($42.00)
  • Cite this Item
Root hair curling and Rhizobium infection in Medicago truncatula are mediated by phosphatidylinositide-regulated endocytosis and reactive oxygen species
Preview not available

Abstract

The symbiotic relationships between legumes and rhizobacteria involve extensive signalling between the two organisms. Studies using genetic, biochemical, and pharmacological approaches have demonstrated the involvement of calcium and reactive oxygen species in the establishment of symbiotic interactions. In the early stage of the interactions rhizobia grow as infection thread within host root hairs and are internalized into the plant cells via endocytosis. It is shown here that inoculation of Medicago truncatula roots with Sinorhizobium meliloti induced a battery of vesicle trafficking genes, including the phosphatidylinositol 3-kinase (PI3K) gene that stimulated plasma membrane endocytosis and the production of reactive oxygen species (ROS). Inhibition of the PI3K suppressed the membrane endocytosis and subsequent oxidative burst and prevented root hair curling and formation of infection threads. Similar effects were produced by inhibition of Ptdlns-specific phospholipase C (PI-PLC). However, neither inhibition of PI3K nor PI-PLC signalling blocked cytosolic Ca2+ influx or early nodulin (ENOD) gene expression. By contrast, the inhibitors induced ENODs transcription in the absence of Rhizobium, suggesting that the expression of ENODs responds to plasma membrane perturbations. In summary, the results show a major reprogramming of intracellular vesicle trafficking during the early stages of symbiotic interactions that co-ordinate the host responses. Activation of parallel signalling pathways leading to $\mathrm{C}{\mathrm{a}}_{\mathrm{c}\mathrm{y}\mathrm{t}}^{2+}$ influx and ROS production that regulate the root hair curling and ENODs expression are also shown.

Page Thumbnails

  • Thumbnail: Page 
[1637]
    [1637]
  • Thumbnail: Page 
1638
    1638
  • Thumbnail: Page 
1639
    1639
  • Thumbnail: Page 
1640
    1640
  • Thumbnail: Page 
1641
    1641
  • Thumbnail: Page 
1642
    1642
  • Thumbnail: Page 
1643
    1643
  • Thumbnail: Page 
1644
    1644
  • Thumbnail: Page 
1645
    1645
  • Thumbnail: Page 
1646
    1646
  • Thumbnail: Page 
1647
    1647
  • Thumbnail: Page 
1648
    1648
  • Thumbnail: Page 
1649
    1649