Phylogenetic Perspectives on Heavy Metal Hyperaccumulation in Fungal Lineages

Catherine Martinez, Jamie B Thompson , Julie A Hawkins

Across the fungal kingdom, the ability to hyperaccumulate and sequester toxic heavy metals from the environment appears to have evolved multiple times. Although in plants, animals, and bacteria the evolution of heavy metal hyperaccumulation is well studied, and despite potential applications of hyperaccumulation in mycoremediation, fungi are under-investigated. Here, we compile a novel dataset from 109 published sources that record hyperaccumulation from 204 species of Fungi, expanding previous compilations more than sixfold. In order to test whether melanisation is predictive of ability to hyperaccumulate, as has been suggested by melanin’s role in reducing oxidative stress, a novel dataset describing the distribution of melanism was also constructed. These data are analysed in a phylogenetic framework, to explore the evolutionary history of heavy metal accumulation in fungi. We identify understudied groups and test whether melanism is over-represented in hyperaccumulating lineages. These analyses reveal potential ‘hot nodes’ for heavy metal hyperaccumulation in Fungi and tentatively support a relationship between hyperaccumulation and melanism. Our dataset and analyses highlight the necessity for further research into fungi and fungal hyperaccumulation, potentially opening new horizons for mycoremediation.