Location: Cereal Crops ResearchTitle: Did the Parastagonospora nodorum necrotrophic effector SnTox3 evolved from SnTox5?
|KARIYAWASAM, GAYAN - North Dakota State University|
|LIU, ZHAOHUI - North Dakota State University|
|STUKENBROCK, EVA - Max Planck Institute For Evolutionary Biology|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/16/2021
Publication Date: 1/9/2022
Citation: Kariyawasam, G.K., Wyatt, N.A., Liu, Z., Stukenbrock, E.H., Faris, J.D., Friesen, T.L. 2022. Did the Parastagonospora nodorum necrotrophic effector SnTox3 evolved from SnTox5? [abstract]. Plant and Animal Genome Conference. Session No.7178.
Technical Abstract: Parastagonospora nodorum is a necrotrophic pathogen of wheat that releases a plethora of necrotrophic effectors to induce programmed cell death (PCD) in the presence of the corresponding host susceptibility genes. To date, five necrotrophic effector genes, including SnToxA, SnTox1, SnTox267, SnTox3 and SnTox5 have been cloned and functionally characterized. The most recently characterized gene, SnTox5 encodes a mature protein with a sequence homology of 45.13% and structural homology of 98% to SnTox3. Therefore, we hypothesized that SnTox3 and SnTox5 weare paralogs that resulted from a gene duplication event. To evaluate this hypothesis, we analyzed the genomic regions of SnTox3 and SnTox5 and found that the two genes share 63.13% sequence identity at the nucleotide level. Repeat annotation revealed a DNA transposable element (TE), TcMar-Fot1 upstream of SnTox5 and a BlastN analysis revealed a homolog of the same TE with 44.25% sequence identity upstream of SnTox3. The similarity of this TE suggests a possible mechanism of gene duplication. To evaluate the direction of the gene duplication, we used whole genome sequences of 387 P. nodorum isolates collected from different regions of the world and found that 48 isolates lacked both genes, 179 encoded both genes, 133 encoded only SnTox5, and 27 encoded SnTox3 only. Haplotype analysis showed that SnTox5 had 27 haplotypes that encoded 21 isoforms, whereas SnTox3 had only 12 haplotypes that encoded four isoforms. Therefore, the prevalence and the haplotype diversity indicate that SnTox3 may have evolved through a duplication of the SnTox5 genomic region involving a DNA TE.