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Sudden Death Syndrome of Soybean Dr. Jason Bond, Plant Pathologist Southern Illinois University 618-453-4309.

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Presentation on theme: "Sudden Death Syndrome of Soybean Dr. Jason Bond, Plant Pathologist Southern Illinois University 618-453-4309."— Presentation transcript:

1 Sudden Death Syndrome of Soybean Dr. Jason Bond, Plant Pathologist Southern Illinois University

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

3 Yield Losses – Northern US Disease 3-year average (bu in millions) Soybean cyst nematode122.4 Phytophthora rot42.1 Seedling diseases41.1 Sudden death syndrome22.7 Charcoal rot17.6 Brown spot16.2 Brown stem rot14.1 Anthracnose11.3 Sclerotinia stem rot10.0 Frogeye leaf spot7.6 Fusarium root rot7.6 Source: Allan Wrather, UM, Portageville, MO

4 Fusarium virguliforme (= F. solani f. 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 ?

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

11 DX

12 DX

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 Valmeyer, IL planted 4/24 Havana, IL planted 4/26 Both fields have a history of SDS.

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

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? Seed Care trials with Scott Cully, Syngenta R&D - Havana and Valmeyer - Fungicide/Nematicide trts.

21 Compacted Soils Vick et al Canadian J. of Plant Path. 28: Vick et al Plant Dis. 87:

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 GTBM 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

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

28 Distribution of SCN Source: G. Tylka, ISU

29 SDS and SCN

30 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 Fv transformant, the GFP- expressing avirulent Fv transformant, or several nematode/fungus co-inoculations The experiment consisted of 36 treatments replicated 5 times

33 Cultivar H. glycines M. incognita F. virguliforme ForrestRRR P94M50RSS SpencerSSS GH3983SSR LS SRR

34 Cultivar H. glycines M. incognita F. virguliforme ForrestRRR P94M50RSS SpencerSSS GH3983SSR LS SRR Avirulent Fv Avirulent Fv + SCN

35 Cultivar H. glycines M. incognita F. virguliforme ForrestRRR P94M50RSS SpencerSSS GH3983SSR LS SRR 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 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 and M. Schmidt B. Diers

38 Evaluating Resistance 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 , Websites, Mail, Popular press, Companies

42 Variety Performance in 2009 Relative DX RatingPercentage of Entries MG Percentage of Entries MG Res Mod. Res Mod. Susc Susc.5446

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 Hashmi et al Plant Health Progress doi: /PHP RS.

44 Waterbath Method

45 Tray Method Pictures – R. Bowen, UIUC

46 1 –Typical plant, showing no symptoms. 3 – Leaf with obvious, inter-veinal chlorosis 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


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