Assortative mating in sympatric ascomycete fungi revealed by experimental fertilizations

Publication date: Available online 15 June 2019Source: Fungal BiologyAuthor(s): Artemis D. Treindl, Adrian LeuchtmannAbstractMate recognition mechanisms resulting in assortative mating constitute an effective reproductive barrier that may promote sexual isolation and speciation. While such mechanisms are widely documented for animals and plants, they remain poorly studied in fungi. As an experimental system, we used two interfertile species of the Epichloë typhina complex (Clavicipitaceae, Ascomycota), which are host-specific endophytes of sympatrically occurring grasses, Dactylis glomerata (infected by E. typhina) and Holcus lanatus (infected by E. clarkii). The life cycle of these obligatory outcrossing fungi entails dispersal of gametes by a fly vector among external fungal structures (stromata). To test for assortative mating, we mimicked the natural fertilization process by applying mixtures of spermatia from both species in various proportions and examined their reproductive success on the stroma. Our trials revealed that fertilization is non-random and preferentially takes place between conspecific mating partners, which is indicative of assortative mating. Additionally, the viability of hybrid and non-hybrid offspring was assessed, by determining germination rates of ascospores produced by experimental matings. Germination rates were lower in E. clarkii than in E. typhina and were reduced in ascospore progeny from treatments with high proportions of heterospecific sp...

Source: Fungal Biology - June 15, 2019 Category: Biology Source Type: research