Targeting of TMV movement protein to plasmodesmata requires the actin/ER network: evidence from FRAP.
Fluorescence recovery after photobleaching (FRAP) was used to study the mechanism by which fluorescent-protein-tagged movement protein (MP) of tobacco mosaic virus (TMV) is targeted to plasmodesmata (PD). The data show that fluorescence recovery in PD at the leading edge of an infection requires elements of the cortical actin/endoplasmic reticulum (ER) network and can occur in the absence of an intact microtubule (MT) cytoskeleton. Inhibitors of the actin cytoskeleton (latrunculin and cytochalasin) significantly inhibited MP targeting, while MT inhibitors (colchicine and oryzalin) did not. Application of sodium azide to infected cells implicated an active component of MP transfer to PD. Treatment of cells with Brefeldin A (BFA) at a concentration that caused reabsorption of the Golgi bodies into the ER (precluding secretion of viral MP) had no effect on MP targeting, while disruption of the cortical ER with higher concentrations of BFA caused significant inhibition. Our results support a model of TMV MP function in which targeting of MP to PD during infection is mediated by the actin/ER network.
Wright
Kathryn M
KM
Programme of Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK. kwrigh@scri.ac.uk
Wood
Nicola T
NT
Roberts
Alison G
AG
Chapman
Sean
S
Boevink
Petra
P
Mackenzie
Katrin M
KM
Oparka
Karl J
KJ
D000199:Actins / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D053830:Plant Viral Movement Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000378:metabolism*; D019810:Sodium Azide / Q000494:pharmacology; D053778:Thiazolidines / Q000494:pharmacology; D014026:Nicotiana / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D053830:Plant Viral Movement Proteins; D053778:Thiazolidines; D020126:Brefeldin A; D003571:Cytochalasin B; D019810:Sodium Azide; C037068:latrunculin B