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Suillus placidus
Suillus placidus photographed by Susan Hopkins.

Suillus placidus

Suillus placidus (Bonord.) Singer is an ectomycorrhizal mushroom-forming fungus. The species associates with Pinus strobus where it exchanges mineral nutrients for photosynthates from its host. It was first described from Europe under planted North American P. strobus (Nguyen et al. 2016).

This mushroom has the distinctive characteristic of being mostly white when young, only turning slightly brown, dingy yellow, or a combination of those colors when fully mature. It appears to have a northerly range of distribution in eastern northern North America that correlates well with the distribution of its hosts. In culture it prefers the use of nitrates as a nitrogen source that puts it into the ‘nitrate fungus’ category. Suillin, a compound made by Suillus species, and specifically from S. placidus, is able to induce apoptosis (programmed cell-death) in human liver cancer cells (Liu et al. 2009).

Suillus as a genus is one of the most common ectomycorrhizal symbionts of the pine family (Pinaceae) in the northern hemisphere. Commonly known as ‘Slippery Jacks’, the mushrooms of this genus provide food for both wildlife and humans. Suillus species have been used in forest restoration following natural and human-made disturbances, have potential for bioremediation (mycoremediation), and likely play an important role in facilitating soil carbon sequestration in mycorrhizal forests.

This genome is part of the Community Science Program (Proposal 502931) “A genome atlas of the ectomycorrhizal genus Suillus: Phylogenetic diversity and population genomics of a keystone guild of symbiotic forest fungi”, a collaborative effort aimed at using genomics data to understand and connect the evolutionary history, ecology, and genomic mechanisms of mutualistic ectomycorrhizal symbionts and their Pinaceae hosts. Please contact the PI for permission prior to the use of any data in publications.


Keller G. 1996. Utilization of inorganic and organic nitrogen sources by high-subalpine ectomycorrhizal fungi of Pinus cembra in pure culture. Mycological Research. 100:989–998, doi:10.1016/S0953-7562(96)80053-0.

Liu F, Luo K, Yu Z, Co N, Wu S, Wu P, Fung K, Kwok T. 2009. Suillin from the mushroom Suillus placidus as potent apoptosis inducer in human hepatoma HepG2 cells. Chemico-Biological Interactions. 181:168–174, doi:10.1016/J.CBI.2009.07.008.

Nguyen NH, Vellinga EC, Bruns TD, Kennedy PG. 2016. Phylogenetic assessment of global Suillus ITS sequences supports morphologically defined species and reveals synonymous and undescribed taxa. Mycologia 108:1216–1228, doi:10.3852/16-106.

Rineau F, Stas J, Nguyen NH, Kuyper TW, Carleer R, Vangronsveld J, Colpaert J V, Kennedy PG. 2016. Ectomycorrhizal fungal protein degradation ability predicted by soil organic nitrogen availability. Applied Environmental Microbiology 82:1391–1400, doi:10.1128/AEM.03191-15.