Evaluation of N orth A merican isolates of S oybean mosaic virus for gain of virulence on Rsv ‐genotype soybeans with special emphasis on resistance‐breaking determinants on Rsv4
Summary Resistance to S oybean mosaic virus ( SMV ) in soybean is conferred by three dominant genes: Rsv1 , Rsv3 and Rsv4 . Over the years, scientists in the USA have utilized a set of standard pathotypes, SMV ‐ G1 to SMV ‐ G7 , to study interaction with Rsv ‐genotype soybeans. However, these pathot...
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Published in | Molecular plant pathology Vol. 13; no. 9; pp. 1077 - 1088 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
01.12.2012
|
Online Access | Get full text |
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Summary: | Summary
Resistance to
S
oybean mosaic virus
(
SMV
) in soybean is conferred by three dominant genes:
Rsv1
,
Rsv3
and
Rsv4
. Over the years, scientists in the
USA
have utilized a set of standard pathotypes,
SMV
‐
G1
to
SMV
‐
G7
, to study interaction with
Rsv
‐genotype soybeans. However, these pathotypes were isolated from a collection of imported soybean germplasm over 30 years ago. In this study, 35
SMV
field isolates collected in recent years from 11 states were evaluated for gain of virulence on soybean genotypes containing individual
Rsv
genes. All isolates were avirulent on
L
78‐379 (
Rsv1
), whereas 19 were virulent on
L
29 (
Rsv3
). On
PI
88788 (
Rsv4
), 14 of 15 isolates tested were virulent; however, only one was capable of systemically infecting all of the inoculated
V
94‐5152 (
Rsv4
). Nevertheless, virulent variants from 11 other field isolates were rapidly selected on initial inoculation onto
V
94‐5152 (
Rsv4
). The
P
3 cistrons of the original isolates and their variants on
Rsv4
‐genotype soybeans were sequenced. Analysis showed that virulence on
PI
88788 (
Rsv4
) was not associated, in general, with selection of any new amino acid, whereas
Q1033K
and
G1054R
substitutions were consistently selected on
V
94‐5152 (
Rsv4
). The role of
Q1033K
and
G1054R
substitutions, individually or in combination, in virulence on
V
94‐5152 (
Rsv4
) was confirmed on reconstruction in the
P
3 cistron of avirulent
SMV
‐
N
, followed by biolistic inoculation. Collectively, our data demonstrate that
SMV
has evolved virulence towards
Rsv3
and
Rsv4
, but not
Rsv1
, in the
USA
. Furthermore, they confirm that
SMV
virulence determinants on
V
94‐5152 (
Rsv4
) reside on
P
3. |
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ISSN: | 1464-6722 1364-3703 |
DOI: | 10.1111/j.1364-3703.2012.00817.x |