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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 #390538

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

Location: Cereal Crops Research

Title: Parastagonospora nodorum necrotrophic effector SnTox5 facilitates the colonization of leaf mesophyll in the presence and absence of Snn5

Author
item KARIYAWASAM, GAYAN - NORTH DAKOTA STATE UNIVERSITY
item RICHARDS, JONATHAN - LOUISIANA STATE UNIVERSITY
item Wyatt, Nathan
item RUNNING, KATHERINE - 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: 12/16/2021
Publication Date: 1/8/2022
Citation: Kariyawasam, G.K., Richards, J.K., Wyatt, N.A., Running, K.L., Liu, Z., Faris, J.D., Friesen, T.L. 2022. Parastagonospora nodorum necrotrophic effector SnTox5 facilitates the colonization of leaf mesophyll in the presence and absence of Snn5 [abstract]. Plant and Animal Genome Conference. Session No.7511.

Interpretive Summary:

Technical Abstract: Parastagonospora nodorum is a destructive pathogen of wheat that is known to release secrete necrotrophic effectors to target wheat susceptibility genes to induce programmed cell death (PCD). Necrotrophic effectors SnToxA, SnTox1, SnTox267, and SnTox3 have been cloned and functionally characterized. We recently used 197 P. nodorum isolates collected from different geographical regions of the US to perform a genome-wide association study (GWAS) to locate and clone SnTox5. We validated SnTox5 by inoculating CRISPR-Cas9 based gene-disruption mutants and gain-of-function transformants of SnTox5 on LP29, the differential line for Snn5. SnTox5 was an intron-free gene that encoded a protein consisting of 217 amino acids with a signal peptide and a pro-sequence. The gene was present in 75.6 % of the isolates used in the GWAS and consisted of 22 haplotypes that encoded 20 protein isoforms. Amino acids at the 155th and the 156th positions of SnTox5 contributed to variation in virulence. Expression of SnTox5 peaked at 24 hours post inoculation, which was prior to the colonization of the mesophyll tissue. Confocal microscopy of LP29 and its Snn5 mutants inoculated with P. nodorum strains that contain SnTox5 showed that SnTox5 played a major role in efficient colonization of the mesophyll tissue in the presence and absence of Snn5, indicating that in addition to targeting Snn5 to induce PCD, SnTox5 also facilitates colonization of the mesophyll. Furthermore, SnTox5 showed high level of homology to SnTox3, and we are currently evaluating the evolutionary history of the two effectors.