Abstract
Key messageA locus on wheat chromosome 2A was found to control field resistance to both leaf and glume blotch caused by the necrotrophic fungal pathogen Parastagonospora nodorum.The necrotrophic fungal pathogen Parastagonospora nodorum is the causal agent of Septoria nodorum leaf blotch and glume blotch, which are common wheat (Triticum aestivum L.) diseases in humid and temperate areas. Susceptibility to Septoria nodorum leaf blotch can partly be explained by sensitivity to corresponding P. nodorum necrotrophic effectors (NEs). Susceptibility to glume blotch is also quantitative; however, the underlying genetics have not been studied in detail. Here, we genetically map resistance/susceptibility loci to leaf and glume blotch using an eight-founder wheat multiparent advanced generation intercross population. The population was assessed in six field trials across two sites and 4 years. Seedling infiltration and inoculation assays using three P. nodorum isolates were also carried out, in order to compare quantitative trait loci (QTL) identified under controlled conditions with those identified in the field. Three significant field resistance QTL were identified on chromosomes 2A and 6A, while four significant seedling resistance QTL were detected on chromosomes 2D, 5B and 7D. Among these, QSnb.niab-2A.3 for field resistance to both leaf blotch and glume blotch was detected in Norway and the UK. Colocation with a QTL for seedling reactions against culture filtrate from a Norwegian P. nodorum isolate indicated the QTL could be caused by a novel NE sensitivity. The consistency of this QTL for leaf blotch at the seedling and adult plant stages and culture filtrate infiltration was confirmed by haplotype analysis. However, opposite effects for the leaf blotch and glume blotch reactions suggest that different genetic mechanisms may be involved.
Highlights
Septoria nodorum blotch (SNB), caused by the necrotrophic pathogen Parastagonospora nodorum (Berk.) is one of the most important fungal diseases of wheat (Triticum aestivum L.) and has been reported in almost all wheat-producing areas worldwide (Ficke et al 2018; Francki 2013; Friesen et al 2007; Oliver et al 2012)
Alchemy and Robigus were relatively resistant to leaf blotch, as low levels of infection were observed in all years, while Soissons and Xi19 were more susceptible compared to the other parents (Fig. 1a)
Broad variation in leaf blotch severity among the Multiparent advanced generation intercross (MAGIC) RILs indicated that the inheritance of SNB resistance was quantitative (Fig. 2a)
Summary
Septoria nodorum blotch (SNB), caused by the necrotrophic pathogen Parastagonospora (synonyms Septoria, Stagonospora) nodorum (Berk.) is one of the most important fungal diseases of wheat (Triticum aestivum L.) and has been reported in almost all wheat-producing areas worldwide (Ficke et al 2018; Francki 2013; Friesen et al 2007; Oliver et al 2012). It can cause lesions on both wheat leaves and glumes, and can reduce grain yield by 30% (Bhathal et al 2003; Wicki et al 1999). The durability of cultivar resistance to SNB is challenged by the variability of the pathogen population within and between locations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
