Russula ochroleuca. Photo credit: Jan Borovicka.

Russula ochroleuca is a very common taxon in acidic soils of coniferous forests as well as in acidic hardwood forests of beech and oak of Europe (Větrovský et al., 2020). It was found to be very common in acidic soils with high N content such as in the coniferous stands of lowland plantations of Central Europe (Kohout et al. 2018) and coniferous mountain spruce forests affected by acidic deposition that are N-saturated (Žifčáková et al. 2016). In both cases, Russula ochroleuca was the most abundant ectomycorrhizal fungus. Furthermore, with lower frequency, the fungus also occurs in N-rich acidic beech and oak sites of central Europe (Bahnmann et al. 2018). The fungus is strictly acidophilic as demonstrated by its disappearance after liming of the forest soils (Rineau et al. 2010). The fact that Russula ochroleuca prefers N-rich soils makes it a suitable model of the functioning of the tree-fungus symbiosis in the system where the trees are not dependent on mycorrhizal N-supply. The fungus forms fruitbodies from August till November. The sporocarp for this genome was collected in a mountainous coniferous forest in the Bavarian Forest, Germany, Central Europe with dominant Fagus sylvatica.