Purification and Characterization of Stagonospora nodorum Toxins and Mapping of Toxin Insensitivity

Abstract

Stagonospora nodorum is a pathogenic fungus of wheat causing Stagonospora nodorum blotch disease, an important disease in western Canada. S. nodorum produces a multitude of host selective toxins (HSTs), which when recognized by corresponding sensitivity gene in wheat results in a compatible interaction. In this study, novel HST-host sensitivity gene interactions were investigated. Two different putative HSTs were identified. SnTox3 was likely one of the HSTs present in S. nodorum isolate Swift Current culture filtrate as the chromosomal location of the compatible sensitivity gene corresponded to that of Snn3 locus. Another putative HST interacting with Tsn1 or a tightly linked sensitivity gene was identified from S. nodorum isolate Langham. SNOG_15679, a candidate gene for production of this putative HST was heterologously expressed in Pichia pastoris which caused chlorosis on a sensitive host. Additional tests will be required to confirm the bioactivity of putative novel HST(s) produced by isolate Langham.