Molecular mechanisms of niche competition by biotrophic smut fungi

Ustilago hordei, the causal agent of covered smut disease of barley, is a facultative biotrophic pathogen that systemically colonizes vegetative organs of host plant without inducing major symptoms. Smut disease is visible in the inflorescences, where the kernels are replaced by fungal spores. Thus, successful fungal reproduction depends on the survival of the host plant throughout the growth period. This project is inspired by two key observations: i) host leaves that are colonized by U. hordei are less susceptible to secondary infection by either the necrotrophic fungal pathogen Botrytis cinerea, as well as by the obligate biotrophic pathogen Blumeria hordei; ii) U. hordei shows direct antagonistic activity towards barley-associated bacteria upon the induction of effector gene expression. Based on these observations, we hypothesize that U. hordei evolved means to compete with other barley-colonizing microbes both by direct antagonism, as well as by the induction of plant resistance. The project aims to gain an understanding of the mechanisms mediating host niche adaptation employed by the biotrophic barley pathogen U. hordei with a focus on secreted proteins, termed effectors.

DFG Programme Research Units

Subproject of FOR 5682:  Mechanisms of adaptation to the host niche in plant-colonizing fungi