Knowledge about the mycorrhizal root traits of plants is critical for understanding ecosystem processes from landscape to global scale. In spite of >130 years of research, information about the mycorrhizal status of plants is scant for multiple taxonomic groups and geographic regions. By critically evaluating published information about mycorrhizal associations from the plant perspective and integrating this information with plant phylogeny, we assigned altogether 335 ectomycorrhizal (EcM) plant genera (ca. 8500 species) into 30 monophyletic lineages. Considering low representation of EcM habit in Gnaphalieae, Myrtoideae, Goodeniaceae and Acacia s.str., we estimate that approx. 6000–7000 plant species from 250 to 300 genera are able to establish EcM symbiosis. We nominated further 22 plant genera (comprising 76 species) that may potentially exhibit EcM habit based on their close phylogenetic proximity to these known EcM groups. EcM plants thus constitute 1.7–2.4% of all accepted higher plant (Embryophyta) species. EcM habit has evolved and persisted two times in various groups of gymnosperms and 28 times in angiosperms over a vast time interval since the Early Jurassic. In addition to these multiple gains, we also recovered several potential losses of EcM habit in Fagales, two groups of Fabales, two groups of Asterales and Myrtoideae that could be attributed to shifts to association with nitrogen-fixing bacteria, shrubby or herbaceous life form or wetland habitat. There is still much confusion about the mycorrhizal status in multiple families where conflicting reports exist and incorrect assignments have rooted themselves deeply in the literature. We also discuss the reasons for conflicting reports and point to further research needs in critical taxa to improve our overall understanding about the evolution of ectomycorrhizal symbiosis in plants.
|Title of host publication||Biogeography of Mycorrhizal Symbiosis|
|Place of Publication||Switzerland|
|Number of pages||61|
|Publication status||Published - 2017|