Oat crown rust caused by Puccinia coronata f. sp. avenae is the most destructive foliar disease of cultivated oat. Characterization of genetic factors controlling resistance responses to Puccinia coronata f. sp. avenae in nonhost species could provide new resources for developing disease protection strategies in oat. We examined symptom development and fungal colonization levels of a collection of Brachypodium distachyon and B. hybridum accessions infected with three North American P. coronata f. sp. avenae isolates. Our results demonstrated that colonization phenotypes are dependent on both host and pathogen genotypes, indicating a role for race-specific responses in these interactions. These responses were independent of the accumulation of reactive oxygen species. Expression analysis of several defense-related genes suggested that salicylic acid and ethylene-mediated signaling but not jasmonic acid are components of resistance reaction to P. coronata f. sp. avenae. Our findings provide the basis to conduct a genetic inheritance study to examine whether effector-triggered immunity contributes to nonhost resistance to P. coronata f. sp. avenae in Brachypodium spp.
Bibliographical noteFunding Information:
Funding: We acknowledge support by the University of Minnesota Experimental Station USDA-NIFA Hatch/Figueroa project MIN-22-058, as well as the USDA-ARS The University of Minnesota Standard Cooperative Agreement (3002-11031-00053115) between S. F. Kianian and M. Figueroa. M. J. Moscou is supported by the Gatsby Foundation and Biotechnology and Biological Sciences Research Council (BB/P012574/1).
© 2018 The American Phytopathological Society.