Plant pathogens. Mitochondrial control of fungal hybrid virulence.

Hybrid species of fungal pathogens that infect wild and cultivated plants are emerging with new virulence and host ranges, posing a threat to agriculture and forestry. Here we show that the virulence of hybrid species of the basidiomycete fungus Heterobasidion annosum (Fr) Bref, a causal agent of root and butt rot in conifers and one of the most economically important forest pathogens, is controlled by their mitochondrial genome. Our results indicate that cooperation between organelles that contain genetic information may influence the phenotype of hybrid phytopathogens.