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Soybean Sudden Death Syndrome:            Research Update      Leonor Leandro, Dept. Plant Pathology, ISULinda Kull, Natio...
Outline• Overview of SDS symptoms and impact• New knowledge about the pathogen  – Toxins and pathogenicity genes• Conditio...
SDS Leaf Symptoms• Yellow and brown spots or streaks  between the veins• Defoliation leaving petioles  attached to the stems
SDS Root Symptoms• Reddish-brown to gray rot  in internal tap root tissue• Poor lateral root growth• Blue spore masses may...
SDS distribution and yield loss in US (2006-2008)                                      IA                                 ...
SDS in 2010   Yield loss estimate: 28 MBu
The SDS Pathogen• Soilborne fungus• Species: Fusarium virguliforme• Produces sickle-shaped spores  that are blue in mass• ...
SDS Disease Cycle                  High soil moisture                                           Toxins moved         Sympt...
When do infections occur?• Can occur as early as seed germination• Older seedlings are more resistant                     ...
Why are older seedlings less susceptible to SDS?Infected 3 days after                         Infected 14 days after      ...
Approaches to IdentifyCandidate Pathogenicity Genes          Madan Bhattacharyya, ISU• Transcriptomic: Based differential ...
Detected transcripts for 97.5% of the14,845 F.virguliforme genes . Less than 100 genes expressed               in infected...
25 of the gene transcripts detected only in the F.       virguliforme infected soybean roots are:12 genes encode enzymatic...
Identification of fungal genes and pathways          involved in the development of SDS                Source: Fakhoury & ...
Disruption of Fvfsr1 in F. virguliforme affects                           the aggressiveness of the pathogen              ...
Favorable Conditions for SDS•   High soil moisture•   Cool temperatures•   Soil compaction•   Plant stress - SCN
Does high soil moisture favor SDS?• SDS epidemic years are usually wetter, especially in June            SDS             T...
When is soil moisture most important?                          Irrigation field trial, Ames, 2011                     50  ...
Are cool seasons more favorable for SDS?• SDS epidemic years are generally cooler• No consistent trend for cool temperatur...
Do other soil microbes interact with SDS?• Soybean Cyst Nematode (SCN)• SDS appears earlier and is  more severe with SCN• ...
What soil factors lead to SDS hotspots?       Fakhoury and Bond (SIU), Malvick (UMN), Leandro (ISU)• No differences betwee...
What soil factors lead to SDS hotspots?   Cultured independent approaches-PCR DGGE (IL)                          DGGE was ...
Soybean Resistance to SDS• Controlled by many genes• Quantitative/partial resistance  – No soybean variety is immune to SD...
Is there foliar resistance to pathogen toxins?• Tested with pathogen culture filtrate assay                               ...
Some soybean lines have resistance to toxins                                   Source: Leandro, ISU
Identification of soybean resistance genes                 using VIGS    Whitham, Hill, Leandro (ISU); Radwan, Clough (UIU...
Can we expect better resistance in the future? • Yes. • Breeders are searching   for new sources of SDS   resistance • Inc...
Germ release AR10SDS MGI (early)AR10SDS: Ripley x IA1008- Ripley MG IV; IA1008 MG I    Line       DI      DI            SC...
Germ release AR11SDS MG II  AR11SDS: Ripley x IA2036       -   Ripley MGIV, IA2036 MGII  Line       DI     DI             ...
New populations for developing resistant linesPopulation Susceptible           Resistant      # Sub-       # of   ID      ...
Does tillage help reduce SDS?Year,       Foliar        Root           Yieldtillage    AUDPC     colonization (%)   (Kg/ha)...
Effects of planting date and tillage                                             ***                                      ...
Effects of planting date and tillage                                             ***                                      ...
Effects of planting date and tillage                                             ***                                      ...
Should planting be delayed to manage SDS?• No! Delayed planting can risk yield potential• Plant fields with history of SDS...
Do seed treatments work against SDS?• No• Commercially available seed treatments are  currently not effective• New product...
How about rotation with other crops?• Previous research is inconclusive• Current research at ISU shows promise    M. Liebm...
Crop rotation study (ISU, 2010)                                  SDS Incidence                                            ...
Funding sources
Questions?
Pest Management - Leonor Leandro, Iowa State Univeristy - Soybean Sudden Death Syndrome
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Pest Management - Leonor Leandro, Iowa State Univeristy - Soybean Sudden Death Syndrome

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Hear an update on the latest research on Soybean Sudden Death Syndrome.

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Pest Management - Leonor Leandro, Iowa State Univeristy - Soybean Sudden Death Syndrome

  1. 1. Soybean Sudden Death Syndrome: Research Update Leonor Leandro, Dept. Plant Pathology, ISULinda Kull, National Soybean Research Laboratory, IUCUCrop Advantage Series 2011
  2. 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. 3. SDS Leaf Symptoms• Yellow and brown spots or streaks between the veins• Defoliation leaving petioles attached to the stems
  4. 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. 5. SDS distribution and yield loss in US (2006-2008) IA (1993) AR (1971) Estimated yield Loss (Mbu)(Raw data provided by A. Wrather)
  6. 6. SDS in 2010 Yield loss estimate: 28 MBu
  7. 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. 8. SDS Disease Cycle High soil moisture Toxins moved Symptoms to leaves developPlants die Cool soil temperature High moistureOverwinters insoil, plant Fungusdebris, and SCN colonizescysts Spores infect roots roots of young plants
  9. 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. 10. 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
  11. 11. Approaches to IdentifyCandidate 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
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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 Students t Students 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
  16. 16. Favorable Conditions for SDS• High soil moisture• Cool temperatures• Soil compaction• Plant stress - SCN
  17. 17. 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
  18. 18. 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
  19. 19. 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
  20. 20. Do other soil microbes interact with SDS?• Soybean Cyst Nematode (SCN)• SDS appears earlier and is more severe with SCN• Pathogens may spread together
  21. 21. 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)
  22. 22. What soil factors lead to SDS hotspots? Cultured independent approaches-PCR DGGE (IL) DGGE was used to screen for polymorphism inSoil samples banding patterns between samples:  Fungal ITS DGGE fingerprint for IL soilIsolate DNADGGE Species Identification by sequencing Source: Fakhoury, SIU
  23. 23. 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
  24. 24. Is there foliar resistance to pathogen toxins?• Tested with pathogen culture filtrate assay Source: Leandro, ISU
  25. 25. Some soybean lines have resistance to toxins Source: Leandro, ISU
  26. 26. 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
  27. 27. Can we expect better resistance in the future? • Yes. • Breeders are searching for new sources of SDS resistance • Incorporating resistance genes into earlier MG
  28. 28. 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
  29. 29. 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 R1AR11 SDS 0 R LR 2-3 58 Dwight 1 R MR 3 59SDS Res. 5SDS Susc. 15 Silvia Cianzio, ISU
  30. 30. New populations for developing resistant linesPopulation 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
  31. 31. Does tillage help reduce SDS?Year, Foliar Root Yieldtillage AUDPC colonization (%) (Kg/ha)2000Disk 47 a 49 a 2850 bNo-till 39 a 48 a 2973 bChisel 24 b 61 b 3258 a2001Disk 149 b 61 b 3324 aNo-till 329 a 67 a 3081 bChisel 185 b 71 a 3244 a Vick et al. (2006)
  32. 32. Effects of planting date and tillage *** NS NS *** *** NS Wrather et al, 1995
  33. 33. Effects of planting date and tillage *** NS NS *** *** NS Wrather et al, 1995
  34. 34. Effects of planting date and tillage *** NS NS *** *** NS Wrather et al, 1995
  35. 35. 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
  36. 36. Do seed treatments work against SDS?• No• Commercially available seed treatments are currently not effective• New products are being tested
  37. 37. 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
  38. 38. Crop rotation study (ISU, 2010) SDS Incidence SDS Severity 100 A 100 A K287RR K287RR 80SDS 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
  39. 39. Funding sources
  40. 40. Questions?

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