Within the framework of the JGI Mycorrhizal Genomics Initiative, we are sequencing a phylogenetically and ecologically diverse suite of mycorrhizal fungi (Basidiomycota and Ascomycota), which include the major clades of symbiotic species associating with trees and woody shrubs. Analyses of these genomes will provide insight into the diversity of mechanisms for the mycorrhizal symbiosis, including endo- and ectomycorrhiza.
Pisolithus is actually a dominant fungus in ecological settings. In fact, P. tinctorius and P. microcarpus species are typically one of the most frequent fungi to colonize pines and eucalypts, respectively, in primary successional settings in their native habitat. They are currently used in the commercial forestry industry to inoculate conifer or eucalypt seedlings for lumber and landscape trees. Pisolithus is a versatile organism, and genomic data on this fungus will be useful to a variety of groups. Sequencing of these species will provide a more comprehensive understanding of the biological community of eucalypt and pine, two trees having their genome currently sequenced by the DOE JGI. Pisolithus is a distant relative to the other fungi slated for sequencing, and this property will yield important insights into evolution of ectomycorrhizal symbiosis, which is a foundation of terrestrial ecosystems. Laccaria bicolor belongs to the Agaricales. Like Rhizopogon and Paxillus, Pisolithus is a member of the Boletales, but it diverged about 130 mya from the other two genera and probably became mycorrhizal independently. It is known that mycorrhizal symbiosis has convergently evolved multiple times in the Basidiomycota. Having genomic information on related multiple lineages would enable us to understand the underlying evolutionary development of this process.