Molecular Plant Pathology - Pathogen Profiles
Potato leafroll virus: a classic pathogen shows some new
Michael Taliansky, Mike A. Mayo and Hugh Barker
Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, UK
||PLRV is the type species of the
genus Polerovirus, in the family Luteoviridae. Isolates are
known from most continents, presumably all spread in potato material
derived from the Andean region of South America.
||PLRV particles are isometric and c.
25 nm in diameter. They contain one major (c. 23 kDa) and one minor
(c. 80 kDa) protein. The genome is a single 5.8 kb positive sense
RNA that has neither a 5'-cap nor 3' poly(A) but carries a VPg.
||PLRV has a limited host range;
about 20 largely solanaceous species have been infected experimentally.
PLRV is a common pathogen of potato, and closely related isolates are
occasionally found in tomato, but no other crops are affected.
||Infection, especially from infected
seed potato stocks, causes leafrolling and stunting, the extent depending
on the potato cultivar.
||The biology of PLRV is that of a
classic luteovirus. Its isometric particles are persistently transmitted
by aphids in a non-propagative manner, it multiplies largely in phloem
tissue and disease symptoms reflect this localization. A decade or so of
molecular study has revealed the many features of PLRV that are
characteristic of its family.
||In recent years some interesting
features of PLRV have emerged that are the focus of further investigation.
These are, its phloem confinement, its movement in infected plants, its
ability to suppress gene silencing and new ideas about the structure of
its particles. This review describes the background to PLRV and points
towards these new developments.
Models of the predicted structure of a reconstituted trimer of PLRV
coat protein. With permission from Terradot et al. (2001; Academic Press
Inc.). (A) Surface (left) or section (right) views. Monomer units are in
light green, dark green or blue. Epitope 5 (residues 83–89) is shown in
red, epitope 120 (residues 172-178) is shown in yellow. (B) Surfaces
coloured according to the properties of the constituent amino acids: D,
E-magenta; R, H, K-blue; A, V, L, I, P, M, F, W-orange; G, S, T, C, N, Q,
Y-green. The acidic patch on the trimer surface is circled.
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