Transcript MSU key messages

Biotic pests in cereal crop production:
plant pathogens
Wheat streak mosaic virus and
Stem Rust Ug99
Mary Burrows, Dai Ito, Matt Moffet, Zach Miller,
Fabian Menalled, Mareike Johnston, Luther Talbert,
Tom Blake, and Phil Bruckner
• Initiated in 2002 by USDA-CSREES with
homeland security funding
• Goal: to provide diagnostic capability to the
nation’s agricultural system
• Five regional hubs with responsibility for
diagnostics, funding, public relations,
epidemiology, and training
Regional Networks of NPDN
North Central Plant
Diagnostic Network
Michigan State University
North Eastern Plant
Diagnostic Network
Cornell University
Western Plant Diagnostic Network
University of California, Davis
Great Plains
Diagnostic Network
Kansas State University
National Agricultural
Pest Information System
Purdue University
South Eastern Plant
Diagnostic Network
University of Florida
Network Responsibilities
•
•
•
•
Data collection (detectors/diagnosticians)
Communications system
Information storage and management
Data analysis
• New events and analysis of new appearance
• Pattern recognition
• Unusual patterns of endemic problems
• GIS
• Event propagation
• Tracking
• Reporting and alerts
• Link to State Departments of Ag and US regulatory
• agencies
WSMV: The Pathogen
• Family Potyviridae, genus Tritimovirus
• Mite-transmitted virus
Wheat streak mosaic virus
• Infects both winter and spring wheat
– Symptoms in spring
• Earlier infection = greater yield loss
• Grassy weeds, volunteer wheat, corn, etc.
can harbor both WSMV and the mite vector
• 5-10% yield loss/yr across Great Plains
• 100% yield loss in individual fields
SDSU Extension
Disease cycle of WSMV
Weed Host: Volunteer Wheat
Table 2. Capacity of prevalent grassy weeds in Montana to serve as mite and virus hosts.*
Common name
Scientific name
Life cycle Mite host WSMV host
Jointed goatgrass
Aegilops cylindricae
Annual
Yes
Yes
Crested wheatgrass
Agropyron cristatum
Perennial Unknown Unknown
Wild oat
Avena fatua
Annual
No
Yes
Smooth brome
Bromus inermis
Perennial
Yes
No
Bromus japonicus
Japanese brome
Perennial
No
Unknown
Downy brome/Cheatgrass Bromus tectorum
Annual
Yes
Yes
Persian darnell
Lolium persicum
Annual
Unknown Unknown
Western wheatgrass
Pascopyrum smithii
Perennial
Yes
No
Feral rye
Secale cereale
Annual
Unknown Unknown
Yellow foxtail
Setaria glauca
Annual
No
No
Green foxtail
Setaria viridis
Annual
Yes
Yes
*data taken from literature cited in text
WSMV in Montana weeds, 2008
Volunteer wheat is the best non-crop host, but weed species are
also are infected with virus and may serve as a source
Which weeds are susceptible?
Common name
Jointed goatgrass
Literature1
Yes
ELISA2
Local
Wild oat
Yes
+
Downy Brome
Crested Wheatgrass
Yes
No
No
No
No
No
Yes
Yes
Local
+
+
-
Thickspike Wheatgrass
Quackgrass
Slender Wheatgrass
Smooth Brome
Barnyardgrass
Green Foxtail
1WSMV
2Data
host data taken from Somsen 1970, Townsend 1996, and Brey, 1998.
from MSU: 'Local' = Virus restricted to inoculated leaves in preliminary assay
Regional variation in the
susceptibility of weeds to WSMV
Figure 1. Susceptibility of grassy weed species in five Great Plains states to Wheat streak mosaic virus (WSMV) as measured by
ELISA of mechanically inoculated plants.
α-WSMV ELISA absorbance relative to infected wheat
(where wheat = 1)
1.6
1.4
1.2
Colorado
Idaho
Montana
Nebraska
Oklahoma
Wheat = 1
1
0.8
0.6
0.4
0.2
0
Downy brome
-0.2
Green Foxtail
Jointed goatgrass
Quackgrass
Wild oat
Increase in regional virus incidence?
Host
SDSU Extension
Vector
（New York Times)
Pathogen
Environment
Wheat virus survey, 2008:
Objectives
• Determine prevalence of wheat viruses in the Great
Plains (WSMV, HPV, TriMV, BYDV-PAV and CYDV-RPV)
• Nine states: WY, MT, CO, KS, OK, TX, SD, ND, NE
• Determine geographic distribution for TriMV & HPV
• Determine if host symptoms are diagnostic among virus
species for single and multiple infections
• Collect and provide virus infected plant tissues to support
research efforts
• Increase communication about wheat viruses in the
Great Plains Region
Objective: Determine prevalence of
wheat viruses
• WSMV detected in all GPDN states at
high percentage infection (10 – 83 %)
• HPV detected in all GPDN states
• HPV identified in MT and WY for the first
time
• TriMV identified in all states, all but KS
new reports
2008
Colorado
Kansas
Montana
Nebraska
North Dakota
Oklahoma
South Dakota
Texas
Wyoming
Total
n
51
53
23
66
44
93
96
307
21
754
WSMV
61
62
43
39
40
27
28
83
38
47
WMoV
10
38
9
8
12
30
7
41
19
19
TriMV
10
30
0
27
0
6
2
57
24
17
145
62
150
100
92
77
44
322
21
1013
50
14
29
14
52
49
27
44
10
32
24
0
4
16
12
17
14
4
19
12
21
2
7
44
.
18
.
14
0
20
2009
Colorado
Kansas
Montana
Nebraska
North Dakota
Oklahoma
South Dakota
Texas
Wyoming
Total
2008
Colorado
Kansas
Montana
Nebraska
North Dakota
Oklahoma
South Dakota
Texas
Wyoming
Total
n WSMV + WMoV WSMV + TriMV
51
8
8
53
15
21
23
9
0
66
8
18
44
9
0
93
16
4
96
7
2
307
37
53
21
5
10
754
13
13
WMoV + TriMV All mite
0
0
13
8
0
0
5
5
0
0
3
3
1
1
28
26
10
0
13
5
2009
Colorado
145
Kansas
62
Montana
150
Nebraska
100
North Dakota
92
Oklahoma
77
South Dakota 44
Texas
322
Wyoming
21
Total
1013
70
14
3
31
63
66
41
48
76
46
67
16
5
57
.
68
.
58
14
46
46
2
1
60
.
36
.
18
10
29
6
0
1
3
.
0
.
2
0
2
Winter wheat: inoculated trials
Winter wheat: inoculated trials
Yield reductions due to spring inoculation with WSMV, 2008 & 2009
Variety
Genou
2008
Yield of control
% yield
(bu/a)
reduction
42.4
24.8
2009
Yield of control
% yield
(bu/a)
reduction
91.4
15.2
CDC Falcon
38.3
-25.1
79.0
18.3
Rampart
45.4
15.6
84.8
15.8
Neeley
35.9
42.6
111.8
34.9
Ledgar
48.5
-31.2
81.3
8.2
Jagalene
37.7
10.3
64.9
0.1
Tiber
32.1
40.9
94.6
26.6
Yellowstone
40.1
13.7
118.3
22.6
Rocky
28.6
19.0
79.5
19.6
Pryor
45.9
-14.4
108.6
14.7
Morgan
38.2
24.2
90.2
23.0
MTV0734
41.6
37.1
78.6
19.7
Average
39.56
13.11
90.26
18.2
Spring wheat: inoculated trials
Spring wheat: inoculated trials
Yield reductions due to inoculation with WSMV, 2008 & 2009
Variety
Reeder
2008
Yield of control
% yield
(bu/A)
reduction
17.7
22.8
2009
Yield of control
% yield
(bu/A)
reduction
67.8
34.2
Choteau
28.5
33.6
60.0
51.9
McNeal
25.5
39.9
60.5
50.4
Conan
25.3
24.2
56.3
32.5
Fortuna
21.0
32.7
52.9
42.2
Ernest
18.5
34.7
64.8
57.3
Corbin
24.4
18.0
56.2
31.9
Hank
31.9
21.8
61.7
28.4
Amidon
11.5
8.8
71.1
38.7
Scholar
18.2
45.9
61.8
44.3
Metcalfe
N/A
N/A
96.1
16.7
Haxby
N/A
N/A
98.4
13.3
Mean
22.2
28.2
67.3
36.8
Race Evolution in TTKS (Ug99) Lineage
&
Implications to Resistance Breeding
Yue Jin, USDA-ARS
Ug99
First reported in Uganda in 1999
--Pretorius et al. 2000 Plant Dis 84:203
Virulent on Sr31
Sr31 is located on 1BL.1RS translocation
Also carries Lr26, Yr9
Increased adaptation and higher yield. As a result,
widely spread in wheat worldwide
Helped to reduce stem rust population worldwide
Virulence to Yr9, originated in the eastern Africa
in mid 80s, caused worldwide epidemics
TTKS
In 2002 and 2004, CIMMYT nursery planted in Njoro,
Kenya were severely infected by stem rust.
In 2005, we identified Kenyan isolates from 2004 were
race TTKS.
--Wanyera, Kinyua, Jin, Singh 2006 Plant Dis 90:113
Broad virulence of TTKS
to North American spring wheat
 US spring wheat CVs of the Northern Great Plains,
known to have broad-based resistance to stem rust,
were mostly susceptible (84%).
 500 CIMMYT CVs released
since 1950’s, 84% were
susceptible.
Conclusion:
Ug99 possesses a unique
virulence combination that
renders many resistance
genes ineffective.
Jin & Singh, 2006, Plant Dis:90:476-480
Evolution of the TTKS lineage
Our data point to:
TTKSK
TTKST
Jin et al. 2008. Plant Dis. 92:923-926
Jin et al. 2009. Plant Dis. (in Press)
Sr24+
Sr31+
Sr36-
Sr24Sr31+
Sr36-
TTTSK
Sr24Sr31+
Sr36+
Ramification of Sr24/Sr36 virulence to US Wheat
based on testing of 2007 elite breeding germplasm
% of resistance to
Type
Entry
TTKSK
TTKST
TTTSK
(Ug99)
Sr24v
Sr36v
Hard red spring
89
21%
12%
21%
Hard red winter
416
29%
15%
28%
Soft red winter
377
27%
25%
11%
Western wheat
60
3%
3%
3%
Total
942
26%
18%
19%
Current status of Ug99
• New races constantly evolving
• Ug99 stalled in Iran due to long drought
• If moves to Pakistan/India will affect 15% of
world’s wheat crop that feeds 1 billion of the
world’s poorest people
• Strain of stem rust in India that overcomes Sr25
• ‘Likely’ Ug99 has already spread beyond Iran Rick Ward, co-coordinator of the Durable Rust Resistance in Wheat project, based
at Cornell university; http://rustopedia.org/traction/permalink/Resources905
Projected potential pathways for Ug99
based on the migration of Yr9 virulence
Singh et al. 2006. CAB Review 1, 54
Ug99 migration
2007
2006
2006
2003?
2005
1998
2001?
2004
Singh et al. 2008. Advances in Agronomy v98
The good news
• Phil and Luther are both working on it
already!
• Li Huang, PSPP, has identified spring wheat
mutants from a population derived by Mike
Giroux with resistance to leaf, stem, and
stripe rust – including all Ug99 derivatives
• Fungicide trials with great results
• Communication and education ramping up!
Wheat stem rust fungicide trial results (2008)
Stem rust (% leaf area)
Stein and Gupta, SDSU
Triazole + Strobilurin
Triazoles
Fungicide modes of action: Triazoles
• FRAC group 3
• DMI (demethylation) inhibitors; biosynthesis of sterols
in fungal cell membrane; spore penetration and
mycelial growth
• Provides 14-21 days of protection
• Medium risk of resistance development
• Greater mobility in plant than strobilurin fungicides
• Most widely used class of fungicide in the world
• Control a wide array of fungal diseases
• Protective and curative effects (if applied early in
disease development)
Fungicide movement in the plant
From: Tenuta, A., D.
Hershman, M. Draper and A.
Dorrence. 2007. Using foliar
fungicides to manage
soybean rust.. Land-Grant
Universities Cooperating
NCERA-208 and OMAF.
Available online at
http://www.oardc.ohiostate.edu/SoyRust/
Fungicide modes of action:
Strobilurins
• FRAC group 11
• QoI (quinone outside) inhibitors (respiration); spore germination,
penetration, and mycelial growth
• Provides 14-21 days of protection
• High risk of resistance development because it has a very
specific mode of action (they block electron transfer at the site of
quinol oxidation (the Qo site) in the cytochrome bc1 complex,
thus preventing ATP formation)
• Originally isolated from wood-rotting fungi Strobilurus tenacellus
• ‘Reduced-risk’ pesticide (pose less risk to human health than
other chemical options at the time of registration by EPA)
• Control a wide array of fungal diseases
• Excellent preventative fungicides, but limited curative effects
• “Plant health benefit” independent of disease control?
Figure 1. Mobility of trifloxystrobin, an example of a
QoI fungicide.
http://www.apsnet.org/education/AdvancedPlantPath/Topics
/Strobilurin/top.htm
Preventing fungicide resistance
• Limit the number of applications of a
single FRAC group per season
• Limit the number of consecutive
applications of a single FRAC group
• Mix fungicides with different modes of
action (FRAC groups)
• Use early in disease development
Stem rust fungicide trial
1. Control
2. Proline 480 SC
3. Prosaro 421 SC
4. Quilt
5. A15590C
6. Alto 100SL
7. Caramba
8. Twinline
9. Headline 2.09EC
10. Gem 500 SC
Rate
Active Ingredient
Company
5.3 oz
7.5 oz
14 oz
14 oz
4 oz
13.5 oz
9 oz
7.5 oz
2.4 oz
Prothioconazole
Tebuconazole + Prothioconazole
Azoxystrobin + Propiconazole
Azoxystrobin + Propiconazole
Cyproconazole
Metconazole
Pyraclostrobin +Metconazole
Pyraclostrobin
Trifloxystrobin
Bayer
Bayer
Syngenta
Syngenta
Syngenta
BASF
BASF
BASF
Bayer
Control (no fungicide), 14 daa
Strobilurin fungicides, 14 daa
Headline
Gem 500 SC
Strobiliurin + Trizole, 14 daa
Quilt
Quilt Xcel
Strobiliurin + Trizole, 14 daa
Twinline
Prosaro
Trizole fungicides, 14 daa
Alto
Caramba
Proline
Compare sprayed and unsprayed plots
Yield, stem rust fungicide trial
2009, Bozeman
120
bcd
bc
Yield (bu/A)
100
80
60
40
20
0
cd
cd
bc
bc
a
a
d
b