Fetid Russula

I found a surprising nitrophilic response to increased nitrogen pollution by a certain group of ectomycorrhizal fungi, the foetid Russula (Avis P.G., 2012. Ectomycorrhizal Iconoclasts: The ITS rDNA diversity and nitrophilic tendencies of foetid Russula. Mycologia. 104(5):998-1007). This is unexpected but exciting, because most mycorrhizal fungi are intolerant of nitrogen pollution. This study (Avis 2012) was the first to use DNA based methods to sort out the diversity of this common, typically dominant yet usually misnamed group of fungi and to understand how common the nitrophilic tendencies are in the group. Two key questions emerged from this research that I am currently working and will continue to pursue in the future:

The first question is who are these fungi as it is clear this group has a substantial amount of taxonomic uncertainty as well as cryptic species to be better described and understood. My most recent focus has been to conduct in-depth phylogenetic analysis of the key clades and members of this group. In so doing, we have identified new taxa and clarified key clades:

Melera S, Ostellari C, Roemer N, Avis PG, Tonolla M, Barja F, Narduzzi-Wicht, B. 2017. Analysis of morphological, ecological and molecular characters of Russula pectinatoides Peck and Russula praetervisa Sarnari, with a description of the new taxon Russula recondita Melera & Ostellari. Mycological Progress. 16(2):117-134.

Adamcik S. et al (Avis P.G., Barajas M., two of 24 co-authors). 2019. The Quest for a Globally Comprehensible Russula Language. Fungal Diversity 99:369-449.

Currently, a set of projects is in progress to understand the diversity of this group in North America, to name additional species of fetid Russula as well as to find sequencing approaches to tackle the problem of the DNA degradation in key type specimens that can further illuminate the phylogenetics and diversity of this group Russula, one of the worlds largest genera of ectomycorrhizal fungi.

The second question is to determine how foetid Russula tolerate high levels of nitrogen pollution. Not yet tested hypotheses included whether these fungi are beneficial for non-nitrogen nutrient uptake (e.g. phosphorus), or alternatively, act parasitically. To test this, I have designed experiments that use symbiotic cultures of tree seedlings and fetid Russula ectomycorrhizas.

One additional area I look to expand upon is to examine the population genetics of these Russula within and around long term nitrogen addition experiments to understand if these fungi are adapting to the novel conditions of the experiments.