Location: Cereal Crops ResearchTitle: Role of non-programmed cell death inducing effectors in the Parastagonospora nodorum-wheat necrotrophic interaction
|KARIYAWASAM, GAYAN - North Dakota State University
|LIU, ZHAOHUI - North Dakota State University
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/6/2023
Publication Date: N/A
Technical Abstract: Effectors are small, secreted cysteine rich proteins that are involved in host-pathogen interactions. Parastagonospora nodorum, which causes septoria nodorum blotch of wheat, has been known to produce multiple necrotrophic effectors that induce programmed cell death (PCD) in wheat genotypes that carry the corresponding susceptibility genes. To date, five necrotrophic effectors including SnToxA, SnTox1,SnTox267, SnTox3 and SnTox5 have been cloned and functionally characterized. However, little is known about the role of non-PCD inducing effectors during infection. Therefore, in this study the proteome of P. nodorum strain Sn2000 was screened using signalP v5.0 and effectorP v3.0 and RNA-Seq data were generated for samples collected at 0, 4, 12, 24, 48, 72, and 96 hours post inoculation of SnTox5 producing isolate Sn2000 on the wheat differential line LP29, which carries the host susceptibility gene Snn5. In silico analysis predicted a total of 563 effectors whereas RNA-Seq analysis supported in planta expression of 435 of those predicted effectors at least once across all the time points. Out of 435, 250 effectors showed at least 100 reads across RNA-Seq libraries and were therefore used in downstream analysis. Differential expression analysis showed 146 effector genes were differentially expressed whereas 104 were constitutively expressed in time points relative to the expression at 0 hpi. InterProScan screening of these effectors revealed, 50 of the predicted effectors are cell wall degrading enzymes, three are chitin binding proteins, seven are proteases, four are necrotrophic effectors, eight provide protection from reactive oxygen species, five provide protection from other host defense mechanisms, and 24 are involved in nutrient break-down. These results, together with temporal gene expression analysis, suggest that these non-PCD inducing effectors not only play a critical role in adhesion, penetration, and colonization, but also provide protection to the fungus in adverse conditions created during PCD. In addition, no function was predicted for 121 effectors and currently we are in the process of functionally characterizing them to understand their role in the P. nodorum infection process.