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

Sudden Death Syndrome of Soybean

Dr. Jason Bond, Plant PathologistSouthern Illinois University

[email protected]

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

Yield Losses – Northern US

Disease3-year average (bu in millions)

Soybean cyst nematode 122.4

Phytophthora rot 42.1

Seedling diseases 41.1

Sudden death syndrome 22.7

Charcoal rot 17.6

Brown spot 16.2

Brown stem rot 14.1

Anthracnose 11.3

Sclerotinia stem rot 10.0

Frogeye leaf spot 7.6

Fusarium root rot 7.6

Source: Allan Wrather, UM, Portageville, MO

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

Symptoms

Similar Foliar Symptoms

Stem Canker

Phytophthora stem rot

Similar Foliar Symptoms

Brown Stem Rot

SDS

Spread of SDS

1971

1984

1984

1984

1984

1986

1986

1992

1986

1986

1993

19972002

2004

1993

2000

1999

2000

1997 1997

1997

1997

2005?

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

DX 25 - 30

DX 50 - 60

DX 60 - 75

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.

Impact on Yield

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

Impact of Planting Date

Aug 18 Aug 25 Sep 1 Sep 100

5

10

15

20

25

30

35

40

45

50

May 10June 2June 27

Planting Date

Dis

ease

Inde

x (D

X)

Date Rated

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.

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

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, ?

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/Nematicide trts.

Compacted Soils

0 2 0 4 0 6 0 8 0 1 0 0 1 2 0

m e t e r

D I S E A S E I N D E X ( M Y E R S , 1 9 9 7 ) , D X .

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

0

1 5

3 0

4 5

6 0

7 5

0 2 0 4 0 6 0 8 0 1 0 0 1 2 0

m e t e r

S O I L M A C R O P O R O S I T Y , %

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

m e

t e

r

6

1 0

1 4

1 8

2 2

2 6

3 0

3 4

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

Pathogen Research

•Identification of fungal genes involved in the development of SDS

•Karyotyping (Chromosomal organization)

• SDS-SCN interaction

A. Fakhoury, Southern Illinois U.

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…)

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

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

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

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

Distribution of SCN

Source: G. Tylka, ISU

SDS and SCN

SDS and SCN

SCN juvenile and mycelium of F. virguliforme

Could Other Nematodes Be Involved?

SDS

Root knot nematode M. incognita

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

97-1610 Spencer GH3983 Forrest P94M500

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Foliar scorch P6B5

P6B5+SCN

P6B5+RKN

Cultivar

Rat

ing

Virulent Fv

Virulent Fv + SCN

Virulent Fv + RKN

Cultivar H. glycines M. incognita F. virguliforme

Forrest R R R

P94M50 R S S

Spencer S S S

GH3983 S S R

LS97-1610 S R R

97-1610 Spencer GH3983 Forrest P94M500

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Foliar scorchP23C5

P23C5+SCN

Cultivar

Rat

ing

Cultivar H. glycines M. incognita F. virguliforme

Forrest R R R

P94M50 R S S

Spencer S S S

GH3983 S S R

LS97-1610 S R R

Avirulent Fv

Avirulent Fv + SCN

97-1610 Spencer GH3983 Forrest P94M500

5

10

15

20

25

30

Root colonization (QPCR)

P23C5

P23C5+SCN

Cultivar

ng

fu

ng

al D

NA

/ug

to

tal

DN

A

Cultivar H. glycines M. incognita F. virguliforme

Forrest R R R

P94M50 R S S

Spencer S S S

GH3983 S S R

LS97-1610 S R R

Avirulent Fv

Avirulent Fv + SCN

Host Resistance

• Quantitative resistance• Controlled by multiple genes• Difficult to test in the field

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 and M. Schmidt B. Diers

B. Diers

Evaluating Resistance to SDS• Illinois Soybean Association

– SDS Commercial Variety Trial

– USDA Uniform and Regional Trials

• North Central Soybean Research Program

−NC Regional Trial

Success equals ?

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

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

SDS Variety TrialsOver 1,800 varieties (includes

Public Lines) MG 1-5

Six locations overall3-4 for each MGOver 16,000 plots

Results distributed via Email, Websites, Mail, Popular press, Companies

www.soybeandiseases.infowww.vipsoybeans.orgwww.soybean.siu.edu

Variety Performance in 2009

Relative DX

Rating Percentage of EntriesMG 1 - 3.4

Percentage of EntriesMG 3.5 - 5.0

0-20 Res. 6 5

21-40 Mod. Res. 17 17

41-60 Mod. Susc.

23 32

61+ Susc. 54 46

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.

Waterbath Method

Tray Method

Pictures – R. Bowen, UIUC

1 –Typical plant, showing no symptoms.

3 – Leaf with obvious, inter-veinal chlorosis

Pictures – R. Bowen, Univ. of Illinois

Pictures – R. Bowen, UIUC

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

Summary

Questions?

Jason P. Bond

[email protected]

618-453-4309