The Parastagonospora nodorum necrotrophic effector SnTox5 targets the wheat gene Snn5 and facilitates entry into the leaf mesophyll

• Published in: The New phytologist Vol. 233; no. 1; pp. 409 - 426
• Main Authors: Kariyawasam, Gayan K., Richards, Jonathan K., Wyatt, Nathan A., Running, Katherine L. D., Xu, Steven S., Liu, Zhaohui, Borowicz, Pawel, Faris, Justin D., Friesen, Timothy L.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.01.2022; John Wiley and Sons Inc
• Subjects: Apoptosis; Ascomycota; Cell death; Colonization; Confocal microscopy; CRISPR; DNA sequences; Gene disruption; Gene editing; Gene mapping; Gene sequencing; Genome-wide association studies; Genome-Wide Association Study; Genomes; genomics; Genotypes; GWAS; Haplotypes; Homology; Lasers; Mesophyll; Microscopy; necrotrophic effector; Nucleotide sequence; Parastagonospora nodorum; pathogen colonization; Pathogenesis; PCR; Plant Diseases - genetics; Plant Leaves; programmed cell death; Proteins; Quantitative trait loci; Triticum - genetics; Wheat; Whole genome sequencing; necrotrophic effector; Parastagonospora nodorum; GWAS; pathogen colonization; genomics; microscopy; wheat; programmed cell death
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.17602

Summary Parastagonospora nodorum is an economically important necrotrophic fungal pathogen of wheat. Parastagonospora nodorum secretes necrotrophic effectors that target wheat susceptibility genes to induce programmed cell death (PCD). In this study, we cloned and functionally validated SnTox5 and characterized its role in pathogenesis. We used whole genome sequencing, genome‐wide association study (GWAS) mapping, CRISPR‐Cas9‐based gene disruption, gain‐of‐function transformation, quantitative trait locus (QTL) analysis, haplotype and isoform analysis, protein modeling, quantitative PCR, and laser confocal microscopy to validate SnTox5 and functionally characterize SnTox5. SnTox5 is a mature 16.26 kDa protein with high structural similarity to SnTox3. Wild‐type and mutant P. nodorum strains and wheat genotypes of SnTox5 and Snn5, respectively, were used to show that SnTox5 not only targets Snn5 to induce PCD but also facilitates the colonization of the mesophyll layer even in the absence of Snn5. Here we show that SnTox5 facilitates the efficient colonization of the mesophyll tissue and elicits PCD specific to host lines carrying Snn5. The homology to SnTox3 and the ability of SnTox5 to facilitate the colonizing of the mesophyll also suggest a role in the suppression of host defense before PCD induction. See also the Commentary on this article by Kanyuka et al., 233: 11–14.