Pest Management - Leonor Leandro, Iowa State Univeristy - Soybean Sudden Death Syndrome
1. Soybean Sudden Death Syndrome:
Research Update
Leonor Leandro, Dept. Plant Pathology, ISU
Linda Kull, National Soybean Research Laboratory, IUCU
Crop Advantage Series 2011
2. 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
3. SDS Leaf Symptoms
• Yellow and brown spots or streaks
between the veins
• Defoliation leaving petioles
attached to the stems
4. 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
5. SDS distribution and yield loss in US (2006-2008)
IA
(1993)
AR
(1971)
Estimated yield
Loss (Mbu)
(Raw data provided by A. Wrather)
7. The SDS Pathogen
• Soilborne fungus
• Species: Fusarium virguliforme
• Produces sickle-shaped spores
that are blue in mass
• Produces round-shaped survival
spores called chlamydospores
8. SDS Disease Cycle
High soil moisture
Toxins moved
Symptoms
to leaves
develop
Plants die
Cool soil temperature
High moisture
Overwinters in
soil, plant Fungus
debris, and SCN colonizes
cysts Spores infect roots roots
of young plants
9. When do infections occur?
• Can occur as early as seed germination
• Older seedlings are more resistant
Seedling age
Root Rot Severity (AUDPC)
2500 at inoculation
2000 0 DAP
1500 3 DAP
1000 7 DAP
500 13 DAP
0
63
17 73
23 84
29
Temperature ( F)
Source: Gongora-Canul and Leandro, ISU
10.
11. Why are older seedlings less susceptible to SDS?
Infected 3 days after Infected 14 days after
planting plating
Xylem
Cortex
Source: Gongora-Canul and Leandro, ISU
12. Approaches to Identify
Candidate Pathogenicity Genes
Madan Bhattacharyya, ISU
• 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
13. Detected transcripts for 97.5% of the14,845 F.
virguliforme genes . Less than 100 genes expressed
in infected tissues only
100%
90%
80%
70%
60% Not expressed
50%
Expressed
40%
30%
20%
10%
0%
Source: B. Sahu and M. Bhattacharyya, ISU
14. 25 of the gene transcripts detected only in the F.
virguliforme infected soybean roots are:
12 genes encode enzymatic functions 13 have unknown functions.
Elastinolytic metalloproteinase Mep Stress responsive A/B barrel domain protein
Monooxygenase FAD-binding protein FAD binding domain-containing protein
Pisatin demethylase MFS transporter
Pectate lyase FAD binding domain-containing protein
Hypothetical protein FOXB_14311
Serine protease inhibitor
Hypothetical protein FOXB_02038
Endo-1,4-beta-xylanase
Exopolygalacturonase Hypothetical protein FOXB_05665
Glycosyltransferase Hypothetical protein FOXB_10278
Hypothetical protein FOXB_09766
Lignostilbene dioxygenase
Hypothetical protein FOXB_10941
Gibberellin 3-beta hydroxylase
Predicted protein
Cellulase
Hypothetical protein FOXB_13583
Fungal cellulose binding domain
protein Hypothetical protein FOXB_09991
Hypothetical protein FOXB_10941
Source: B. Sahu and M. Bhattacharyya, ISU
15. Identification of fungal genes and pathways
involved in the development of SDS
Source: Fakhoury & Bond, SIUC
• 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
15
Source: Fakhoury & Bond, SIUC
16. Disruption of Fvfsr1 in F. virguliforme affects
the aggressiveness of the pathogen
A
Control WT ΔFvfsr1
B
10 8 5
9 7
Mean(Amount of DNA in ng)
4
8
7 C 6
D 3
Forest
Foliar ratings (ds)
Foliar ratings (ds)
6 5 2
5 4
1
4 3
Variety
0
3 2 5
2
1
1
Mean(Amount of DNA in ng)
4
0 0
3
Spencer
-1 -1
Control F14 Mont-1 Each Pair Control F14 Mont-1 Each Pair 2
Student's t Student's t
1
Treatments 0.05 Treatments 0.05
0
Spencer (Susceptible soybean Forest (Resistant soybean
Mont-1 Control F14
T reatments
cultivar) cultivar )
F. virguliforme level in infected soybean
(Mont-1 (WT), F14 (ΔFvfsr1) and control roots of wild type (Mont-1), ΔFvfsr1
(no fungus) four weeks after planting (F14) and control (no fungus)
16
Source: Fakhoury & Bond,Bond, SIUC
Fakhoury & SIUC
17. Favorable Conditions for SDS
• High soil moisture
• Cool temperatures
• Soil compaction
• Plant stress - SCN
18. Does high soil moisture favor SDS?
• SDS epidemic years are usually wetter, especially in June
SDS Total Precipitation (inches)
Year Incidence Apr May Jun Jul Aug
2007 Low 4.3 5.3 3.5 3.1 9.1
2008 High 5.6 5.5 8.9 5.5 1.7
2010 Very high 3.8 4.6 10.3 8.1 4.5
2011 Low 3.0 4.5 4.9 3.5 1.7
Mean High 4.3 4.9 8.7 6.9 4.5
Mean Low 3.4 5.9 4.1 3.3 5.1
Mean 30-year 3.0 4.1 4.6 3.8 3.8
Source: Robertson, Mueller, and Leandro, ISU
19. When is soil moisture most important?
Irrigation field trial, Ames, 2011
50
46.2 bu/ac
SDS Severity (%)
40
V5-R6
30 50.2
R1-R6
20 R3-R6
10 55
No irrigation
47.6
0
Susceptible Resistant
Soybean Variety
Source: Leandro, ISU
20. Are cool seasons more favorable for SDS?
• SDS epidemic years are generally cooler
• No consistent trend for cool temperatures at planting
SDS Soil Temperature oC (F)
Incidence Apr May Jun Jul Aug
High SDS 9.0 16.1 21.1 24.7 24.1
(48.2) (61) (70) (76.4) (75.4)
Low SDS 11.1 17.4 23.3 26.9 25.1
(51.8) (63.3) (73.9) (80.4) (77.2)
30-year 9.8 16.3 22.1 25.1 24.1
(49.6) (61.3) (71.8) (77.2) (75.4)
Source: Robertson, Mueller, and Leandro, ISU
21. Do other soil microbes interact with SDS?
• Soybean Cyst Nematode (SCN)
• SDS appears earlier and is
more severe with SCN
• Pathogens may spread
together
22. What soil factors lead to SDS hotspots?
Fakhoury and Bond (SIU), Malvick (UMN), Leandro (ISU)
• 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)
23. What soil factors lead to SDS hotspots?
Cultured independent approaches-PCR DGGE (IL)
DGGE was used to screen for polymorphism in
Soil samples banding patterns between samples:
Fungal ITS DGGE fingerprint for IL soil
Isolate DNA
DGGE Species
Identification
by sequencing
Source: Fakhoury, SIU
24. 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
25. Is there foliar resistance to pathogen toxins?
• Tested with pathogen culture filtrate assay
Source: Leandro, ISU
27. Identification of soybean resistance genes
using VIGS
Whitham, Hill, Leandro (ISU); Radwan, Clough (UIUC)
30
Inoculate with a LSD=9.6 3C12-1
virus vector 25
containing gene 3D7-1
SDS severity (%)
of interest 20 3D10-1
Radwan, UIUC 3F5-5
15
Jar-1
10 b
Coi-1
b b
5 b H-92
Expose plants to b b
b
F. virguliforme 0
Mock-V2
culture filtrates
Radwan, UIUC
28. Can we expect better resistance in the future?
• Yes.
• Breeders are searching
for new sources of SDS
resistance
• Incorporating
resistance genes into
earlier MG
29. Germ release AR10SDS MGI (early)
AR10SDS: Ripley x IA1008- Ripley MG IV; IA1008 MG I
Line DI DI SCN IDC Yield
Field Gh
HGT7 HGT 2.5.7 bu/a
R3 R1
AR10SDS 2 1 R NR 2-4 51
IA1008 3-4 52
MN 1606 10 2
Suscept. 20 10
Silvia Cianzio, ISU
30. Germ release AR11SDS MG II
AR11SDS: Ripley x IA2036 - Ripley MGIV, IA2036 MGII
Line DI DI SCN IDC Yield
Field Gh
HGT7 HGT bu/a
R3 2.5.7
R1
AR11 SDS 0 R LR 2-3 58
Dwight 1 R MR 3 59
SDS Res. 5
SDS Susc. 15
Silvia Cianzio, ISU
31. New populations for developing resistant lines
Population Susceptible Resistant # Sub- # of
ID parent parent popul. RIL
Screened:
SDS, SCN, and
AX19286 A95- LS94-3207** 11 391 molecular
684043* screening
AX19287 A95-684043 LS98-0582** 10 435
AX19286 (A95-
AX19288 A95-684043 LS99-2235** 1 392
684043 X LS94-
3207):
AX19289 IA1006*** LS94-3207 4 446
o 20 highly SDS
resistant (3
AX19290 IA1006 LS98-0582 3 471 protocols)
o 15 also are
AX19291 IA1006 LS99-2235 1 85 highly resistant
to SCN
AX19294 IA2050 LS94-3207 8 461
*- SCN resistant ; ** - SDS resistant ; ***- BSR resistant
Cianzio and Bhattacharyya, ISU
32. Does tillage help reduce SDS?
Year, Foliar Root Yield
tillage AUDPC colonization (%) (Kg/ha)
2000
Disk 47 a 49 a 2850 b
No-till 39 a 48 a 2973 b
Chisel 24 b 61 b 3258 a
2001
Disk 149 b 61 b 3324 a
No-till 329 a 67 a 3081 b
Chisel 185 b 71 a 3244 a
Vick et al. (2006)
33. Effects of planting date and tillage
***
NS
NS
*** *** NS
Wrather et al, 1995
34. Effects of planting date and tillage
***
NS
NS
*** *** NS
Wrather et al, 1995
35. Effects of planting date and tillage
***
NS
NS
*** *** NS
Wrather et al, 1995
36. Should planting be delayed to manage SDS?
• No! Delayed planting can risk yield potential
• Plant fields with history of SDS last
Planting Date
Crop Advantage Series 2010 Palle Pedersen, ISU
37. Do seed treatments work against SDS?
• No
• Commercially available seed treatments are
currently not effective
• New products are being tested
38. How about rotation with other crops?
• Previous research is inconclusive
• Current research at ISU shows promise
M. Liebman, L. Leandro, A. Robertson, C. Chase, D. Mueller
3-year rotation / 2-year rotation
Photo courtesy of L. Miller
39. Crop rotation study (ISU, 2010)
SDS Incidence SDS Severity
100 A 100 A
K287RR K287RR
80
SDS incidence (%)
SDS Severity (%)
80 K2918
K2918
60
B
60
a B
40 40
a
20 20 b b
b B b B
0 0
S2 S3 S4 S2 S3 S4
Rotation Treatments YIELD (Bu/Acre)
S2 corn-soybean Rotation K-287RR K-2918
S3 corn-soybean-oat/red clover S2 42 22
S4 corn-soybean-oat/alfalfa - alfalfa
S3 54 55
S4 55 53
Leandro, Liebman, Robertson, M
r, Chase, ISU
Good afternoon everyone. It’s a pleasure to be here today to talk to you about SDS. This presentation will be team tagged between myself and Linda KullI will give you research update on SDS and Linda will give you a clicker survey to help us direct research needsWe have tried to leave plenty of time for questions at the end of the presentation, but please feel free to ask questions as we go along
Here is the outline of the presentation ….
The areas between the leaf veins will turn bright yellow, then eventually brown. The dead, brown tissue between veins may fall out, leaving large ragged holes in leaves.The leaf blades will fall off of the petioles (petioles are the thin “stems” that connect the leaf blades to the main stem), but the petioles remain attached to the stem
Soybean roots will appear rotted, with poor lateral root development, and plants will be easily pulled from the soil.The fungus that causes the disease may appear as blue fungal growth (spore masses) on the main or tap root of the soybean plant.When split lengthwise with a knife, the internal tissue of the main or tap root will be gray to reddish brown, not healthy white.
Here is a map of the states where it has been detected and estimated yield losses from 2006-2008. States with stronger color report more yield losses. I’m showing the first detection in AR and the year of detection in IA
The pathogen in the US is F. v. (previously F. solani F. sp. glycinesIn other countries – SA there are several other species
9C=48F11C=52F
Our project at ISU has released the first public line with resistance to SDS and of early maturity adapted to Iowa. The disease index is very good compared to a resistant line from Minnesota, it has a good iron deficiency chlorosis score, and it is of MG I. It has been licensed by several breeding programs, both public and private seed company for use in their own breeding programs. The line is also resistance to SCN race 3. We have learned thru work conducted by Leonor, that having dual resistance to SCN is important to the lines resistant to SDS.
More recently, we have released another line AR11SDS, with also good disease resistance, 0 very comparable to another cultivar of MG IV and to the resistance check. It also has resistance to SCN nematode race 3, and appropriate iron deficiency score. Fortunately, it also has a better yield level compared to an acceptable cultivar such as Dwight.This line has had very good acceptance in the soybean breeding environment, it has been licensed by numerous programs for use in their cultivar development efforts.
Our look to the near future. We are working with another group of lines, derived from crosses to different lines possessing SDS resistance. We now want to expand the genetic base of resistance to SDS, by using different and highly superior resistant lines. The LS lines are all donors of SDS resistance genes that were released by Southern Illinois University in Carbondale. The are of MG IV and a bit later, however, the other parent of the lines are of early MGI, II, and III. The genes will be placed into the early maturity groups for use in Iowa.In the bright blue, we are showing a population that looks very promising for our conditions. We identified 20 lines in it that are highly resistant to SDS, and most importantly of those, 15 are also resistance to SCN. The SCN resistant parent traces also to new sources of SCN resistance, which is an additional bonus for all of us, in trying to protect our soybeans. We do need other sources of SCN in addition to those that trace to PI 88788. And A95-684043 has different sources of SCN in addition to PI 88788.
For a particular planting date ….lets look at mid-may planting for variety essex
In several varieties we saw lower in SDS in the later planting dates compared to early planting- and that was true for the different tillage practices
Companion cropped– red clover under seeded2yr- fall chisel plowing, spring field cultivation before corn and soybean3yr - Similar plus disk tilling before oat/red clover, several to incorporate red clover
