pest management - leonor leandro, iowa state univeristy - soybean sudden death syndrome
DESCRIPTION
Hear an update on the latest research on Soybean Sudden Death Syndrome.TRANSCRIPT
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Crop Advantage Series 2011
Soybean Sudden Death Syndrome: Research Update
Leonor Leandro, Dept. Plant Pathology, ISULinda Kull, National Soybean Research Laboratory, IUCU
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Outline
• Overview of SDS symptoms and impact• New knowledge about the pathogen
– Toxins and pathogenicity genes• Conditions that favor SDS
– Moisture – Microbial interactions
• Disease Management – New genetics– Cultural practices
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SDS Leaf Symptoms
• Yellow and brown spots or streaks between the veins
• Defoliation leaving petioles attached to the stems
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SDS Root Symptoms
• Reddish-brown to gray rot in internal tap root tissue
• Poor lateral root growth• Blue spore masses may be
visible on root surface
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SDS distribution and yield loss in US (2006-2008)
(Raw data provided by A. Wrather)
IA(1993)
AR(1971) Estimated yield
Loss (Mbu)
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SDS in 2010 Yield loss estimate: 28 MBu
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• Soilborne fungus• Species: Fusarium virguliforme• Produces sickle-shaped spores
that are blue in mass • Produces round-shaped survival
spores called chlamydospores
The SDS Pathogen
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SDS Disease Cycle
Spores infect roots of young plants
Cool soil temperatureHigh moisture
Overwinters in soil, plant debris, and SCN cysts
Toxins moved to leavesSymptoms
develop
High soil moisture
Fungus colonizes
roots
Plants die
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When do infections occur?
• Can occur as early as seed germination• Older seedlings are more resistant
17 23 290
500
1000
1500
2000
2500
0 DAP
3 DAP
7 DAP
13 DAP
Temperature (°F)
Root
Rot
Sev
erity
(AU
DPC
) Seedling age at inoculation
63 73 84
Source: Gongora-Canul and Leandro, ISU
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Does infection time affect leaf symptoms?
• Seedlings infected at older ages develop less foliar symptoms
0
500
1000
1500
2000
0 DAP3 DAP7 DAP13 DAP
Temperature (F)
Folia
r sev
erity
(AU
DPC
)
Seedling age at inoculation
63 73 84
Source: Gongora-Canul and Leandro, ISU
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Why are older seedlings less susceptible to SDS?
Infected 3 days after planting
Infected 14 days after plating
Cortex
Xylem
Source: Gongora-Canul and Leandro, ISU
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Madan Bhattacharyya, ISU
Approaches to Identify Candidate Pathogenicity Genes
• Transcriptomic: Based differential expression of genes in infected tissues vs. mycelia and germinating spores.
• Proteomics: Proteome of the xylem sap of infected soybean seedlings
• Metabolomics: Metabolites of diseased and healthy soybean leaves
Source: Bhattacharyya, ISU
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Detected transcripts for 97.5% of the14,845 F. virguliforme genes . Less than 100 genes expressed
in infected tissues only
Spore
Myc
elia
Early
infe
ctio
n
Late
infe
ctio
n
Only
Infe
ctio
n
Total E
xpre
ssed
0%
10%20%30%40%50%60%70%80%90%
100%
Not expressed
Expressed
Source: B. Sahu and M. Bhattacharyya, ISU
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Elastinolytic metalloproteinase Mep Monooxygenase FAD-binding proteinPisatin demethylase Pectate lyase Serine protease inhibitor Endo-1,4-beta-xylanase Exopolygalacturonase GlycosyltransferaseLignostilbene dioxygenaseGibberellin 3-beta hydroxylase
Cellulase Fungal cellulose binding domain protein
25 of the gene transcripts detected only in the F. virguliforme infected soybean roots are:
Stress responsive A/B barrel domain proteinFAD binding domain-containing protein MFS transporterFAD binding domain-containing proteinHypothetical protein FOXB_14311Hypothetical protein FOXB_02038
Hypothetical protein FOXB_05665 Hypothetical protein FOXB_10278Hypothetical protein FOXB_09766 Hypothetical protein FOXB_10941 Predicted protein Hypothetical protein FOXB_13583Hypothetical protein FOXB_09991Hypothetical protein FOXB_10941
12 genes encode enzymatic functions 13 have unknown functions.
Source: B. Sahu and M. Bhattacharyya, ISU
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Source: Fakhoury & Bond, SIUC
15
Identification of fungal genes and pathways involved in the development of SDS
• Genes involved in early events in pathogenesis – Hydrolases (Fvsnf1,…)
• Genes facilitating the colonization of host tissue – Kinases (Fvfsr1, Fvpmk1,…)
• Genes involved in tolerance of antimicrobial compounds produced by the host (Fvgrx2, Fvtrx1,…) S. Mansouri
Source: Fakhoury & Bond, SIUC
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16
0
1
2
3
4
5
Mean(A
mount of D
NA
in
ng)
Forest
0
1
2
3
4
5
Mean(A
mount of D
NA
in
ng)
Spencer
Varie
ty
Mont-1 Control F14
TreatmentsSpencer (Susceptible soybean cultivar)
Disruption of Fvfsr1 in F. virguliforme affects the aggressiveness of the pathogen
(Mont-1 (WT), F14 (ΔFvfsr1) and control (no fungus) four weeks after planting
F. virguliforme level in infected soybean roots of wild type (Mont-1), ΔFvfsr1 (F14) and control (no fungus)
ΔFvfsr1WTControlBA
Folia
r rati
ngs (
ds)
-1
0
1
2
3
4
5
6
7
8
9
10
Control F14 Mont-1
Treatments
Each Pair
Student's t
0.05
Folia
r rati
ngs (
ds)
-1
0
1
2
3
4
5
6
7
8
Control F14 Mont-1
Treatments
Each Pair
Student's t
0.05
DC
Forest (Resistant soybean cultivar )
Fakhoury & Bond, SIUC Source: Fakhoury & Bond, SIUC
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Favorable Conditions for SDS
• High soil moisture • Cool temperatures • Soil compaction • Plant stress - SCN
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Does high soil moisture favor SDS?
SDS Total Precipitation (inches)
Year Incidence Apr May Jun Jul Aug2007 Low 4.3 5.3 3.5 3.1 9.12008 High 5.6 5.5 8.9 5.5 1.72010 Very high 3.8 4.6 10.3 8.1 4.52011 Low 3.0 4.5 4.9 3.5 1.7
Mean High 4.3 4.9 8.7 6.9 4.5Mean Low 3.4 5.9 4.1 3.3 5.1Mean 30-year 3.0 4.1 4.6 3.8 3.8
• SDS epidemic years are usually wetter, especially in June
Source: Robertson, Mueller, and Leandro, ISU
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When is soil moisture most important?
Susceptible Resistant0
10
20
30
40
50
V5-R6R1-R6R3-R6No irrigation
SDS
Seve
rity
(%)
Irrigation field trial, Ames, 2011
Soybean Variety
47.6
55
50.2
46.2 bu/ac
Source: Leandro, ISU
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Are cool seasons more favorable for SDS?
SDS Soil Temperature oC (F)
Incidence Apr May Jun Jul Aug
High SDS 9.0 (48.2)
16.1(61)
21.1(70)
24.7(76.4)
24.1(75.4)
Low SDS 11.1(51.8)
17.4(63.3)
23.3(73.9)
26.9(80.4)
25.1(77.2)
30-year 9.8(49.6)
16.3(61.3)
22.1(71.8)
25.1(77.2)
24.1(75.4)
• SDS epidemic years are generally cooler
• No consistent trend for cool temperatures at planting
Source: Robertson, Mueller, and Leandro, ISU
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Do other soil microbes interact with SDS?
• Soybean Cyst Nematode (SCN)• SDS appears earlier and is
more severe with SCN• Pathogens may spread
together
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What soil factors lead to SDS hotspots?
• No differences between hotspots and healthy spots:– Soil abiotic properties (N, P, K, org. matter, texture, etc)– SCN density
• Differences found in microbial populations– F. virguliforme density in soil– Diversity of fungal communities– Diversity of nematode communities
Source: Fakhoury (SIU)
Fakhoury and Bond (SIU), Malvick (UMN), Leandro (ISU)
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Cultured independent approaches-PCR DGGE (IL)
Soil samples
DGGE
Isolate DNA
Species Identification by sequencing
DGGE was used to screen for polymorphism in banding patterns between samples:
Fungal ITS DGGE fingerprint for IL soil
Source: Fakhoury, SIU
What soil factors lead to SDS hotspots?
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Soybean Resistance to SDS
• Controlled by many genes • Quantitative/partial resistance
– No soybean variety is immune to SDS• Two independent resistance mechanisms
– Root resistance / foliar resistance
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Is there foliar resistance to pathogen toxins?
• Tested with pathogen culture filtrate assay
Source: Leandro, ISU
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Some soybean lines have resistance to toxins
Source: Leandro, ISU
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Identification of soybean resistance genes using VIGS
Whitham, Hill, Leandro (ISU); Radwan, Clough (UIUC)
LSD=9.6
0
5
10
15
20
25
30
3C12-1
3D7-1
3D10-1
3F5-5
Jar-1
Coi-1
H-92
Mock-V2
SD
S s
ever
ity
(%)
a
b
b
b
b b
bb
Inoculate with virus vector containing gene of interest
Radwan, UIUC
Radwan, UIUC
Expose plants to F. virguliforme culture filtrates
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Can we expect better resistance in the future?
• Yes.• Breeders are searching
for new sources of SDS resistance
• Incorporating resistance genes into earlier MG
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Germ release AR10SDS MGI (early)
AR10SDS: Ripley x IA1008- Ripley MG IV; IA1008 MG I
Line DI Field
DI Gh
SCN IDC Yield
HGT7R3
HGT 2.5.7 R1
bu/a
AR10SDS 2 1 R NR 2-4 51
IA1008 3-4 52
MN 1606 10 2
Suscept. 20 10
Silvia Cianzio, ISU
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Germ release AR11SDS MG IIAR11SDS: Ripley x IA2036 - Ripley MGIV, IA2036 MGII
Line DI Field
DI Gh
SCN IDC Yield
HGT7R3
HGT 2.5.7
R1
bu/a
AR11 SDS 0 R LR 2-3 58
Dwight 1 R MR 3 59
SDS Res. 5
SDS Susc. 15
Silvia Cianzio, ISU
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New populations for developing resistant lines Populati
on IDSusceptible parent
Resistant parent
# Sub-popul
.
# of RIL
AX19286 A95-684043*
LS94-3207**
11 391
AX19287 A95-684043
LS98-0582**
10 435
AX19288 A95-684043
LS99-2235**
1 392
AX19289 IA1006***
LS94-3207
4 446
AX19290 IA1006 LS98-0582
3 471
AX19291 IA1006 LS99-2235
1 85
AX19294 IA2050 LS94-3207
8 461
*- SCN resistant ; ** - SDS resistant ; ***- BSR resistant
Screened: SDS, SCN, and molecular screening
AX19286 (A95-684043 X LS94-3207): o 20 highly SDS
resistant (3 protocols)
o 15 also are highly resistant to SCN
Cianzio and Bhattacharyya, ISU
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Does tillage help reduce SDS?Year, tillage
Foliar AUDPC
Root colonization (%)
Yield(Kg/ha)
2000Disk 47 a 49 a 2850 bNo-till 39 a 48 a 2973 b Chisel 24 b 61 b 3258 a2001Disk 149 b 61 b 3324 a No-till 329 a 67 a 3081 bChisel 185 b 71 a 3244 a
Vick et al. (2006)
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Effects of planting date and tillage
Wrather et al, 1995*** *** NS
***
NS
NS
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Effects of planting date and tillage
Wrather et al, 1995*** *** NS
***
NS
NS
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Effects of planting date and tillage
Wrather et al, 1995*** *** NS
***
NS
NS
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Crop Advantage Series 2010
Should planting be delayed to manage SDS?
• No! Delayed planting can risk yield potential • Plant fields with history of SDS last
Palle Pedersen, ISU
Planting Date
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Do seed treatments work against SDS?
• No• Commercially available seed treatments are
currently not effective• New products are being tested
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How about rotation with other crops? • Previous research is inconclusive• Current research at ISU shows promise
Photo courtesy of L. Miller
3-year rotation / 2-year rotation
M. Liebman, L. Leandro, A. Robertson, C. Chase, D. Mueller
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Crop rotation study (ISU, 2010)
Leandro, Liebman, Robertson, Mueller, Chase, ISU
Rotation TreatmentsS2 corn-soybeanS3 corn-soybean-oat/red cloverS4 corn-soybean-oat/alfalfa - alfalfa
S2 S3 S40
102030405060708090
100SDS Severity
K287RRK2918
SDS
Seve
rity
(%)
A
BB
b b
a
S2 S3 S40
102030405060708090
100SDS Incidence
K287RRK2918
SDS
inci
denc
e (%
)
a
A
b BBb
YIELD (Bu/Acre)Rotation K-287RR K-2918
S2 42 22S3 54 55S4 55 53
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Funding sources
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Questions?