Comparative Cellular Analysis of Pathogenic Fungi with a Disease Incidence in Brachypodium distachyon and Miscanthus x giganteus

Based on a growing demand on renewable energy, fast growing perennial grasses have been identified as energy crops with a high capacity in sustainable biomass production. Among these grasses, the giant reed Miscanthus x giganteus delivers one of the highest biomass yields. Despite its potential for an extended cultivation, only little is known about putative fungal pathogens that might cause biomass losses. Molecular targets that are related to fungal resistance have not been identified because cellular and molecular tools have not been established in this energy crop. Therefore, our study was aimed to evaluate a method to compare the penetration process of fungal plant pathogens in the model grass Brachypodium distachyon and M. giganteus. In a screening with 13 different fungal species on detached leaves, we identified four filamentous fungi that infected both B. distachyon and M. giganteus and have not been previously described as M. giganteus pathogens. Spray inoculations with these four fungi on intact M. giganteus leaves of whole plants confirmed their pathogenicity. Microscopic analysis of the fungal infections and the hyphal propagation within the leaf tissue revealed that the four newly identified fungi used very similar strategies for penetration and colonization in B. distachyon and M. giganteus. This suggests that B. distachyon could be suitable to establish model pathosystems for these fungal pathogens that colonize M. giganteus. The already existing genetic tools for B. distachyon might improve the identification of defense-related targets and mechanisms supporting fungal resistance in M. giganteus.