Agrocybe aegerita as a model basidiomycete to study the molecular genetics of fruiting body morphogenesis
Besides the major goal to understand the molecular mechanisms controlling the complex process of fruiting body formation in Agaricomycetes, yield and quality increase in edible mushroom production are another important goal of model basidiomycete-based research. For exhibiting certain upsides, molecular genetics-based studies on fruiting body formation are currently performed with a few well-established model agaricomycete species, i.e. Coprinopsis cinerea, Schizophyllum commune and Agaricus bisporus. Unfortunately, they all also display considerable individual downsides. C. cinerea and S. commune are for example not marketable as edible mushrooms in western industrialised countries and they exhibit untypical fruiting body development traits compared to other Agaricomycetes. A. bisporus, on the other hand, cannot be considered a ’text-book’ basidiomycete. The black poplar mushroom Agrocybe aegerita (also referred to as A. cylindracea), which has also been employed as a transformation-accessible model fungus previously, is a commercially grown high-quality agaricomycete mushroom with the outstanding capability of monokaryotic fruiting. In order to explore the molecular genetics controlling agaricomycete fruiting body development using A. aegerita as a model system, we have selected a set of A. aegerita standard wildtype strains. This includes a dikaryon, A. aegerita AAE-3, and a pair of mating-compatible monokaryotic strains derived from this dikaryon, the monokaryons A. aegerita AAE-3-13 and A. aegerita AAE-3-32, representing the extremes of the monokaryotic fruiting spectrum, which additionally brings along accessibility to a protoplast-based transformation procedure we developed. The selected strain set exhibits both ‘text-book’ basidiomycete and other highly beneficial features such as dikaryotic hyphae bearing clamps, a dikaryotic fruiting body formation which is completed after three weeks, monokaryotic oidiation and monokaryotic fruiting on standard agar media. Given the transformation accessibility of A. aegerita and the whole-genome of the selected A. aegerita standard wildtype strains sequenced and in silico annotated, A. aegerita appears to become a promising modern model system to study monokaryotic and normal dikaryotic mushroom formation applying molecular genetics approaches.