The genus Suillus is comprised of approximately 100 accepted species that is known throughout the Northern Hemisphere and introduced into the Southern Hemisphere along with pine plantations. It is arguably one of the most widespread genera of ectomycorrhizal fungi on the planet. The genus as a whole is emerging as a model system for studying linkages among ectomycorrhizal fungal diversity, ecosystem function, and host plant coevolution. Approaches to studying these questions comes from an integration of systematics that serve as a backbone using phylogenetic inference and taxonomy to describe and name new species, experiments from both natural and lab settings to understand the ecology of these fungi, and genomic tools that allows for the understanding of the molecular interactions between different Suillus species, their hosts and their environment.
Systematics is the upstream step where we generate evolutionary hypotheses and refine species concepts that serve as the framework for downstream studies in ecology, evolution, and genomics. The current understanding of Suillus evolution and co-evolution with their Pinaceae host still require much attention, starting with building a robust multilocus phylogeny of the genus, as well as correlating co-evolutionary patterns with their hosts.
Suillus species are effective ectomycorrhizal symbionts of some members of the Pinaceae, including Pinus, Larix, Pseudotusga, perhaps Picea, and one species even has alternative angiosperm hosts. We start with questions regarding host-specificity, competitive interactions, nutrient flow, and microbiome associations. The many members of the genus has great potential for many ecological studies because they are some of the few ectomycorrhizal genera that can colonize seedlings from spores.
Evolutionary understanding of genus comes from various genomic perpectives. We are currently using transcriptomics to understand host specificity patterns between Suillus and the Pinaceae. We are also using genomics to understand population structures, environmental selection pressures, and genome evolution from bottleneck events of several widespread species.