Soybean defense mechanisms against Sclerotinia sclerotiorum. Mehdi Kabbage University of Wisconsin-Madison

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1 Soybean defense mechanisms against Sclerotinia sclerotiorum Mehdi Kabbage University of Wisconsin-Madison

2 Sclerotinia sclerotiorum Programmed Cell Death Soybean resistance mechanisms Pathogen virulence factors Plant programmed cell death Fungal programmed cell death Identify resistance players NADPH Oxidases Lignin Pathway Transcriptomic and metabolimic studies comparing resistance and susceptibility in Soybeans Factors involved in Oxalic Acid (OA) production Understand pathogenic development Identify essential genes to target via HIGS How animal inhibitors of apoptosis function in cytoprotection in plants to abiotic and biotic stresses Identification of functional equivalents of Mammalian inhibitors of apoptosis Characterization of known cell death players

3 Resistance and lifestyles! Biotrophs Single gene resistance: Can be controlled by a single gene (R gene) Recognizes pathogen proteins (effectors) Triggers a strong defense localized cell death Often complete resistance May not be durable

4 Resistance and lifestyles! Necrotrophs Resistance controlled by multiple genes: Several processes control resistance Partial resistance Durable (does not rely on a single gene) Difficult to pinpoint and transfer Absence of gene products can be important

5 S. sclerotiorum causes Sclerotinia stem rot (SSR) in soybean

6 Michigan White mold epidemic of 2014 Photo courtesy: Martin Nagelkirk, MSU

7 Resistance to S. sclerotiorum in breeding populations McCaghey et al., 2017

8 Dynamics of soybean pathways during resistance and susceptible responses to S.sclereotiorum

9 Differentially regulated processes between resistant and susceptible soybean lines Ranjan et al. Submitted

10 ROS regulation Oxalic acid induces PCD in plants in an ROS dependent manner Kim et al. MPMI 2008

11 ROS regulation NADPH oxidases also known as respiratory burst oxidase homologs (RBOHs) (Sagi and Fluhr, 2006) We have identified 19 RBOH homologs from soybean databases

12 Phylogenetic tree of Glycine max respiratory oxidase homologs (GmRBOHs) Group II Group I Group III Group IV Group V Group VI Ranjan et al. MPP 2017

13 Ranjan et al. MPP 2017

14 Ranjan et al. MPP 2017

15 Ranjan et al. MPP 2017

16 Virus induced gene silencing (VIGS) using Bean pod mottle virus (BPMV) vector ligation VIGS of PDS gene leads to discoloration of leaf Empty vector control VIGS of Gmpds

17 Silencing of soybean RBOH-VI leads to decreased H 2 O 2 during pathogenic development Ranjan et al. MPP 2017

18 Silencing of soybean RBOH-VI enhances resistance to S. sclerotiorum Ranjan et al. MPP 2017

19 Overexpression of GmRBOH-VI leads to enhanced susceptibility to S. sclerotiorum in N. benthamiana aha Ranjan et al. MPP 2017

20 Silencing of soybean RBOH-VI confers drought tolerance Ranjan et al. MPP 2017

21 Differentially regulated processes between resistant and susceptible soybean lines Ranjan et al. Submitted

22 Resistance to S. sclerotiorum in breeding populations

23 Red stem extract inhibits the growth of S. sclerotiorum 1,8 Fresh weight of of S. sclerotiorum (g) 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 DMSO Green stem extract Red stem extract Red stem extract DMSO Green stem extract Ranjan et al. In Preparation

24 Dynamics of soybean pathways during resistance and susceptible responses to S.sclereotiorum

25 Lignin Content is Inversely Related to White Mold Resistance Peltier, A.J., Hatfield, R.D., and Grau, C.R Soybean stem lignin concentration relates to resistance to Sclerotinia sclerotiorum. Plant Dis. 93:

26 Ferulates (Lignin biosynthetic pathway intermediates) are significantly upregulated in the resistant line following S. Sclerotiorum infection Ferulic acid inhibits growth of S. sclerotiorum Caffeic acid affects S. sclerotiorum development Ranjan et al. In Preparation

27 Effect of lignin aldehydes on S. sclerotiorum growth Sinapaldehyde Coniferaldehyde Coumaraldehyde DMSO 250µg/ml 500µg/ml 1000µg/ml

28 Chemical genomics

29 Yeast mutants that are sensitive or resistant to the red node extract Phospholipid and ergosterol biosynthesis Ranjan et al. Submitted

30 Quantification of Ergosterol level in S. sclerotiorum following treatment with red node extract Treatment with red node extract leads to significant decrease of ergosterol synthesis in S. sclerotiorum Ranjan et al. Submitted

31 Summary of soybean-s. sclerotiorum interaction

32 Screening ferulates for bioactivity Piotrowski et al. PNAS 2015

33 Poacic acid as a fungicide Ergosterol/Ergosterol biosynthesis is likely not the target of Poacic acid Piotrowski et al. PNAS 2015

34 Chemical genomics Piotrowski et al. PNAS 2015

35 Chemical genomics predicts poacic acid targets the fungal cell wall Piotrowski et al. PNAS 2015

36 Poacic acid induced morphologies are similar to other cell wall drugs Caspofungin Piotrowski et al. PNAS 2015

37 Poacic acid causes rapid cell lysis - PA + PA Poacic acid targets β-1,3-glucan Piotrowski et al. PNAS 2015

38 Yue et al. Industrial Crops and Products 2017

39 O Maille Nature Views 2015

40 Lab members: Ashish Ranjan Megan McCaghey Collaborators: Damon Smith, UW John Ralph, UW Jeff Piotrowski, UW Craig Grau, UW Marty Chilvers, MSU Daren Mueller, ISU Steve Witham, ISU Brett Williams, QUT Funding: