International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

Genome wide association in Parastagonospora nodorum identifies novel necrotrophic effectors with unique characteristics


Timothy Friesen*
USDA-ARS, Edward T. Schafer Agricultural Research Center, Fargo, ND USA
Department of Plant Pathology, North Dakota State University, Fargo, ND USA

Jonathan Richards
Department of Plant Pathology, North Dakota State University, Fargo, ND USA

Gayan Kariyawasam
Department of Plant Pathology, North Dakota State University, Fargo, ND USA

Zhaohui Liu
Department of Plant Pathology, North Dakota State University, Fargo, ND USA

Justin Faris
USDA-ARS, Edward T. Schafer Agricultural Research Center, Fargo, ND USA


Oral Presentation
Host-Pathogen Interactions

Moore Auditorium, UCD O'Brien centre for Science
23 May 2019, 14:40

View this abstract online by visting isclb2019.com/see/ABS87377

Parastagonospora nodorum, employs necrotrophic effector (NE) proteins to facilitate disease. These NEs target host sensitivity genes to initiate defense response pathways including programmed cell death (PCD), with the result being to the advantage of the pathogen rather than the host. Nine NE-sensitivity gene interactions have been observed within this pathosystem, however, genes encoding SnTox2 and SnTox6 remained undiscovered. Genome resequencing of 198 P. nodorum isolates and phenotyping of host differential lines enabled an association mapping (AM) approach to identify novel NEs. AM using 322,613 polymorphisms identified loci associated with virulence on differential lines BG223 (Snn2) and ITMI37 (Snn6). The putative SnTox2 and SnTox6 marker trait associations mapped to the same locus on chromosome 14, indicating that Snn2 and Snn6 were targeted by the same NE. Disruption of the top candidate gene at the SnTox2/6 locus in isolate Sn4 resulted in the loss of virulence on both Snn2 and Snn6 differential lines, as well as failure to detect Snn2 and Snn6 QTL when inoculated onto the corresponding wheat mapping populations that segregate for Snn2 and Snn6. Transformation of avirulent isolate Sn79-1087 with SnTox2/6 resulted in virulence on lines harboring Snn2 and Snn6, as well as detection of the Snn2 and Snn6 QTL. SnTox2/6 is upregulated in planta, reaching peak expression at 24 hours post-inoculation. The results indicate SnTox2/6 is a single NE which elicits PCD via detection by two non-homoeologous host targets.