Sudden Death Syndrome of Soybean

1. Sudden Death Syndrome of Soybean Dr. Jason Bond, Plant Pathologist Southern Illinois University jbond@siu.edu 618-453-4309

2. Sudden Death Syndrome • Disease and Impact • Pathogen Biology • Cultural Management • Host Resistance

3. Yield Losses – Northern US Source: Allan Wrather, UM, Portageville, MO

4. Fusarium virguliforme (= F. solanif. sp. glycines) • Soilborne, root rotting fungus that colonizes tap root and crown • Produces a toxin(s) • Foliar symptoms generally start at R2 in field

5. Symptoms

6. Similar Foliar Symptoms Stem Canker Phytophthora stem rot

7. Similar Foliar Symptoms • Brown Stem Rot • SDS

8. Spread of SDS 1993 2002 1997 2005? 2000 1993 1999 2004 1997 1986 2000 1984 1992 1986 1984 1997 1986 1984 1971 1984 1997 1997 1986

9. Rating Foliar Symptoms • Disease Incidence (DI) - % of plants in the plot showing leaf symptoms. • Disease Severity (DS) - Severity of diseased plants scored on a 1-9 scale. • Disease Index (DX) = (DI*DS)/9

10. DX 25 - 30

11. DX 50 - 60

12. DX 60 - 75

13. Impact on Yield • SDS is correlated to the yield potential provided by the environment • Popular misconception that SDS does not cause yield loss Yield loss occurs when infection occurs early in a high yielding environment (adequate rainfall), and symptoms are expressed at or near flowering.

14. Impact on Yield

15. Environment SDS severity is increased with: Early planted fields Compacted soil High moisture, low soil temperature during vegetative growth Cool period during flowering Presence of soybean cyst nematode Crop rotations – inconsistent

16. Impact of Planting Date Disease Index (DX) Date Rated

17. Impact of Planting Date 2009 – SDS Variety Trials Havana, IL planted 4/26 Valmeyer, IL planted 4/24 Both fields have a history of SDS.

18. Impact of Planting Date 2009 – SDS Variety Trials Carbondale, IL planted 5/20 Paris, IL planted 5/29 Both fields have a history of SDS, Carbondale was also infested with the pathogen.

19. Chemical Control • Current fungicides do not limit SDS in the field • Some fungicides impact severity in greenhouse trials • Herbicides can reduce symptom severity in the field • Lactofen (X.B. Yang, Iowa State U.) • Experimental products • Generally, short lived reduction • Induced resistance, affecting toxin movement or expression, ?

20. Chemical Control • Could a product provide short-term protection to mirror that observed with delayed planting? - 2010 Seed Care trials with Scott Cully, Syngenta R&D - Havana and Valmeyer - Fungicide/Nematicidetrts.

21. Compacted Soils Vick et al. 2005. Canadian J. of Plant Path. 28:77-83. Vick et al. 2003. Plant Dis. 87:629-632.

22. Pathogen Research • Identification of fungal genes involved in the development of SDS • Karyotyping (Chromosomal organization) • SDS-SCN interaction A. Fakhoury, Southern Illinois U.

23. Pathogen Research • Generate REMI mutants • ~800 mutants have been generated so far • Mutants screened for conidiation and growth pattern • Generate and collaborate to generate sequence material • Necessary in identifying targets for disruption • Expedite gene disruption • Permits genomic and comparative genomic studies (complements karyotyping, population studies…)

24. Tools Developed • Optimize transformation system • Optimize site directed mutagenesis • Optimize transformation system • A split-maker approach is being tested to disrupt genes • Several genes are being targeted at this point • Snf1, grx, fsr1 and several kinases • A GFP expressing strain of the pathogen was produced

25. Objectives • Identification of fungal genes involved in the development of SDS • Identification and characterization of pathways involved in virulence and pathogenesis • Detection of the karyotypic variation among F. virguliforme isolates

26. Karyotypic Variation Among Isolates • F. virguliforme has 11 chromosomes • We estimate the size of the genome at ~ 33 Mbp • Tested isolates exhibited polymorphism (differences) in terms of the sizes of their chromosomes • This polymorphism may be linked to the varying levels of aggressiveness exhibited by different isolates of the pathogen GTBM

27. SDS interactions with SCN • Synergistic – • Roy et al., 1989- greenhouse • McLean and Lawrence, 1993 - greenhouse • Rupe et al., 1991, field trials • Hershman et al., 1990, field trials • Xing and Westphal, 2006, microplots • Additive • Gao et al., 2006 - greenhouse

28. Distribution of SCN Source: G. Tylka, ISU

29. SDS and SCN

30. SDS and SCN SCN juvenile and mycelium of F. virguliforme

31. Could Other Nematodes Be Involved? SDS Root knot nematode M. incognita

32. Greenhouse trial Soybean cultivars were selected that differed for resistance to SCN, RKN, or SDS Each cultivar was challenged with the GFP-expressing virulent Fvtransformant, the GFP-expressing avirulentFvtransformant, or several nematode/fungus co-inoculations The experiment consisted of 36 treatments replicated 5 times

34. Avirulent Fv Avirulent Fv + SCN

35. Avirulent Fv Avirulent Fv + SCN

36. Host Resistance • Quantitative resistance • Controlled by multiple genes • Difficult to test in the field

37. Host Resistance • Mapped genes from PI 567374 in greenhouse. • Genes on linkage group D2 and I. • Mapped genes from Ripley in field with SSR markers using field data. • Genes on linkage group D2 and L. • Genes have been confirmed and are conducting marker-assisted backcrossing B. Diers B. Diers B. Diers and M. Schmidt

38. EvaluatingResistance to SDS • Illinois Soybean Association • SDS Commercial Variety Trial • USDA Uniform and Regional Trials • North Central Soybean Research Program • NC Regional Trial

39. Success equals ? A successful trial has a mean DX of at least 15 – 20 in susceptible check varieties.

40. Factors That Insure Success • Field with history of SDS and/or inoculation when needed • Early planting • Irrigation • Disease evaluation at R6 • Appropriate check varieties • for the maturity group • A good rating scale

41. SDS Variety Trials Over 1,800 varieties (includes Public Lines) MG 1-5 Six locations overall 3-4 for each MG Over 16,000 plots Results distributed via Email, Websites, Mail, Popular press, Companies www.soybeandiseases.info www.vipsoybeans.org www.soybean.siu.edu

42. Variety Performance in 2009

43. Greenhouse Assays • Benefits/Limitations • More art than science • Agreement with known field reactions • Hashmi obtained correlation of .80 • Collaborative university trials – Several blind trial competitions yielded correlations 0 - .59 Hashmi et al. 2005. Plant Health Progress doi:10.1094/PHP-2005-0906-01-RS.

44. Waterbath Method

45. Tray Method Pictures – R. Bowen, UIUC

46. 3 – Leaf with obvious, inter-veinalchlorosis 1 –Typical plant, showing no symptoms. Pictures – R. Bowen, Univ. of Illinois

47. Pictures – R. Bowen, UIUC

48. Wish List • Resistant commercial varieties and public germplasm • Chemical treatments – seed, foliar, in-furrow • Factors that contribute to severe disease • Increased resolution and consistency in field trials • More efficient greenhouse/laboratory screening assays

49. Summary

50. Questions? Jason P. Bond jbond@siu.edu 618-453-4309