Challenging the dogma of host specialization in rust fungi by exploiting their sexual phase

Rust fungi represent the most specie-rich and economically important group of plant pathogens. Traditionally, the host range of rust fungi has followed the dogma of being highly specific to their hosts, however this classification has in many cases been contradictory. In the case of cereal rust fungi, the definition of host range is even more complex with the presence of botanically unrelated plant species, where sexual reproduction occurs. Here we propose to challenge these historic host boundaries of rust fungi. We hypothesize that offspring resulting from sexual crosses between pairs of different agronomically important rust species can alter host range boundaries and provide unique novel knowledge about the genetic arsenal used by the pathogen for host specialization. This completely new approach will have wide implications for fundamental understanding of host range boundaries that will infer in the future design of more durable and effective disease management strategies.