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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #360069

Research Project: Host-Pathogen Interactions in Fungal Diseases of Wheat and Barley

Location: Cereal Crops Research

Title: A single necrotrophic effector from Parastagonospora nodorum has two susceptibility targets in wheat

item RICHARDS, JONATHAN - North Dakota State University
item KARIYAWASAM, GAYAN - North Dakota State University
item LIU, ZHAOHUI - North Dakota State University
item Faris, Justin
item Friesen, Timothy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Parastagonospora nodorum is an economically important pathogen of cultivated wheat. Disease is facilitated by pathogen-produced necrotrophic effectors interacting with host susceptibility targets, resulting in necrotrophic effector triggered susceptibility. Nine interactions have been identified and the cloning and validation of three P. nodorum necrotrophic effectors have been reported, including SnToxA, SnTox1, and SnTox3. In the current research, we used 198 isolates collected from the different wheat producing regions of the United States. Full genome sequences were obtained for all 198 isolates and these isolates were phenotyped on a panel of 24 wheat lines. These lines included both popular cultivars and characterized differential lines specific to the known necrotrophic effectors, including the differential lines for Snn2 (BG223) and Snn6 (ITMI37) which are sensitive to SnTox2 and SnTox6, respectively. Using 322,613 single nucleotide polymorphism (SNP) and insertion/deletion (InDel) markers and a genome wide association study (GWAS) approach, a single locus was significantly associated with virulence on BG223 (Snn2+) and ITMI37 (Snn6+). Analysis of annotated genes underlying the association revealed a single gene encoding a predicted small secreted protein, candidate SnTox2/6. The development of gene disruption mutants of SnTox2/6 in isolate Sn4 abolished the interaction with Snn2 and Snn6, as evidenced by inoculation and QTL analysis of the BG and ITMI wheat populations, respectively. Additionally, transformation of avirulent isolate Sn79-1087 with a functional copy of SnTox2/6 resulted in increased virulence on lines harboring Snn2 or Snn6. Gene expression analysis was conducted via qPCR, revealing 24 hours post-inoculation as the time point of highest gene expression. These results indicate that SnTox2/6 is a single small secreted protein that targets two non-homoeologous host sensitivity/susceptibility gene products to induce cell death leading to pathogen proliferation and sporulation.