|Helliwell, Emily - PURDUE UNIV.|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 4, 2007
Publication Date: May 30, 2008
Citation: Helliwell, E., Goodwin, S.B. 2007. Early growth of a nonhost pathogen, Mycosphaerella graminicola, on barley [abstract]. Phytopathology. 98:202 Technical Abstract: Mycosphaerella graminicola causes Septoria tritici blotch of wheat, but not barley. Septoria passerinii causes speckled leaf blotch of barley and is closely related to M. graminicola, but does not infect wheat. Our goal was to analyze the early growth of M. graminicola during nonhost interactions with barley compared to R-gene and susceptible interactions of barley inoculated with S. passerinii, and R-gene and susceptible interactions of wheat inoculated with M. graminicola. Trypan blue staining showed that M. graminicola germinates on barley leaves and enters via the stomata similarly to wheat, but fungal growth stagnates shortly after penetration. Staining with 3,3-diaminobenzidine showed an accumulation of H2O2 around stomatal cells and, later, epidermal cells, indicating a possible hypersensitive response. Quantitative real-time PCR showed differences in fungal biomass among the interactions. These data show that M. graminicola penetrates cells and triggers production of reactive oxygen species, providing further evidence for an active defense response of barley to this wheat pathogen.