Two Is Better Than One: Studying - Compatibility by Using a Hybrid Pathogen.

Pathogenic fungi can have devastating effects on agriculture and health. One potential challenge in dealing with pathogens is the possibility of a host jump (i.e., when a pathogen infects a new host species). This can lead to the emergence of new diseases or complicate the management of existing threats. We studied host specificity by using a hybrid fungus formed by mating two closely related fungi: , which normally infects spp., and , which normally infects barley. Although was unable to infect spp., the hybrid could. These hybrids also displayed the same mating-type bias that had been observed in and provide evidence of a dominant spore-killer-like system on the sex chromosome of . By analyzing the genomic composition of 109 hybrid strains, backcrossed with over four generations, we identified three regions associated with infection on spp. and 75 potential virulence candidates. The most strongly associated region was located on chromosome 8, where seven genes encoding predicted secreted proteins were identified. The fact that we identified several regions relevant for pathogenicity on spp. but that none were essential suggests that host specificity, in the case of , is a multifactorial trait which can be achieved through different subsets of virulence factors.