Location: Cereal Crops ResearchTitle: Marker development, saturation mapping, and high-resolution mapping of the Septoria nodorum blotch susceptibility gene Snn3-B1 in wheat
|SHI, GONGJUN - North Dakota State University|
|BANSAL, URMIL - University Of Sydney|
|CLOUTIER, SYLVIE - Agriculture And Agri-Food Canada|
|WICKER, THOMAS - University Of Zurich|
|RASMUSSEN, JACK - North Dakota State University|
Submitted to: Molecular Genetics and Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 7/18/2015
Publication URL: http://handle.nal.usda.gov/10113/62086
Citation: Shi, G., Zhang, Z., Friesen, T.L., Bansal, U., Cloutier, S., Wicker, T., Rasmussen, J.B., Faris, J.D. 2016. Marker development, saturation mapping, and high-resolution mapping of the Septoria nodorum blotch susceptibility gene Snn3-B1 in wheat. Molecular Genetics and Genomics. 291:107-119.
Interpretive Summary: Septoria nodorum blotch is a severe fungal disease of wheat. The fungus produces small proteins known as necrotrophic effectors (NEs), and when NEs are recognized by specific genes in wheat the plant becomes diseased. One of these wheat ‘susceptiblity’ genes is known as Snn3-B1, and it was previously located to a specific chromosome in wheat. Here, we developed DNA markers and used molecular mapping techniques to more precisely locate the gene. Molecular mapping located Snn3-B1 to a small region of the short arm of wheat chromosome 5B. Some of the markers developed in this research will be useful to wheat breeders to identify lines lacking the Snn3-B1 gene and thus having higher levels of resistance to Septoria nodorum blotch. The markers, maps and other resources developed in this research will be useful for the isolation of the DNA sequence that corresponds to the Snn3-B1 gene, which will further our knowledge of this wheat-pathogen interaction and lead to better disease management strategies.
Technical Abstract: Septoria nodorum blotch (SNB), caused by Parastagonospora nodorum, is a severe foliar and glume disease on durum and common wheat. Pathogen-produced necrotrophic effectors (NEs) are the major determinants for SNB on leaves. One such NE is SnTox3, which evokes programmed cell death and leads to disease when recognized by the wheat Snn3-B1 gene. Here, we developed saturated genetic linkage maps of the Snn3-B1 region using two F2 populations derived from the SnTox3-sensitive line Sumai3 crossed with different SnTox3-insensitive lines. Markers were identified and/or developed from various resources including previously mapped simple sequence repeats (SSRs), bin-mapped expressed sequence tags (ESTs), single nucleotide polymorphisms (SNPs), and whole genome survey sequences. Subsequent high-resolution mapping of the Snn3-B1 locus in 5,600 gametes delineated the gene to a 1.5 cM interval. Analysis of micro-colinearity of the Snn3-B1 region indicated that it was highly disrupted compared to rice and Brachypodium distachyon. The screening of a collection of durum and common wheat cultivars with tightly linked markers indicated they are not diagnostic for the presence of Snn3-B1, but can be useful for marker-assisted selection if the SnTox3 reactions of lines are first determined. Finally, we developed an ethyl methanesulfonate (EMS)-induced mutant population of Sumai3 where the screening of 408 M2 families led to the identification of 17 SnTox3-insensitive mutants. These mutants along with the markers and high-resolution map developed in this research provide a strong foundation for the map-based cloning of Snn3-B1, which will broaden our understanding of the wheat-P. nodorum system and plant-necrotrophic pathogen interactions in general.