September
2000
, Volume
13
, Number
9
Pages
962
-
974
Authors
Tony J.
Lough
,
1
,
3
Natalie E.
Netzler
,
1
Sarah J.
Emerson
,
1
Paul
Sutherland
,
1
Fiona
Carr
,
2
David L.
Beck
,
1
William J.
Lucas
,
1
,
3
and
Richard L. S.
Forster
1
Affiliations
1Horticulture and Food Research Institute of New Zealand, Plant Health and Development Group, Private Bag 92 169, Auckland, New Zealand; 2Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, U.K.; 3Section of Plant Biology, Division of Biological Sciences, University of California, Davis 95616, U.S.A.
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RelatedArticle
Accepted 11 May 2000.
Abstract
The triple gene block proteins (TGBp1-3) and coat protein (CP) of potexviruses are required for cell-to-cell movement. Separate models have been proposed for inter-cellular movement of two of these viruses, transport of intact virions, or a ribonucleoprotein complex (RNP) comprising genomic RNA, TGBp1, and the CP. At issue therefore, is the form(s) in which RNA transport occurs and the roles of TGBp1-3 and the CP in movement. Evidence is presented that, based on microprojectile bombardment studies, TGBp1 and the CP, but not TGBp2 or TGBp3, are co-translocated between cells with viral RNA. In addition, cell-to-cell movement and encapsidation functions of the CP were shown to be separable, and the rate-limiting factor of potexvirus movement was shown not to be virion accumulation, but rather, the presence of TGBp1-3 and the CP in the infected cell. These findings are consistent with a common mode of transport for potex-viruses, involving a non-virion RNP, and show that TGBp1 is the movement protein, whereas TGBp2 and TGBp3 are either involved in intracellular transport or interact with the cellular machinery/docking sites at the plasmodesmata.
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© 2000 The American Phytopathological Society