EARTH SCIENCES DEPARTMENT SEMINARS
Thursday 11th April
Thursday 11th April
MINERALOGY SEMINAR ROOM
One way of forest plants to make their living in deep shade: eating mycorrhizal fungi.
Mark Andre Selosse, Muséum national d’Histoire Naturelle,Paris, & Centre d'Ecologie Fonctionnelle et Evolutive Montpellier
The evolution of land plants provided repeated emergences of mycoheterotrophy, where achlorophyllous plants exploit carbon from their mycorrhizal fungi. I will briefly review the current knowledge on mycoheterotrophs, mainly orchids and Montropoideae (Ericaceae), and their specific basidiomycetous fungal partners, that also form ectomycorrhizae with surrounding trees. By contrast, subtropical and tropical species often connect to arbuscular-mycorrhizal fungi, or even to saprotrophic basidiomycetes. I will then focus on the evolution from the ‘usual’ mycorrhizal functioning (where autotrophic plants furnish carbon to fungi) to mycoheterotrophy. Intermediate evolutionarily steps were discovered, i.e. green, photosynthetic plants that partly use carbon from their mycorrhizal fungi. This mixotrophic nutrition pre-disposed to evolution of mycoheterotrophy. In some mixotrophic, green orchids, the rare survival of achlorophyllous plants (albinos) further supports the use of fungal carbon. Our investigations of albinos‘ nutrition and fitness nevertheless clarify why emergence of mycoheterotrophy is rare in evolution of mixotrophs, and thus why mixotrophy can be evolutionarily metastable.
Evolutionary history of mycorrhizas
Christine Strullu-Derrien, Dept. of Earth Sciences, NHM
Nowadays fungi form widespread mutualistic associations with over 90% of plant species. Of the two predominant types, the most common and widespread are the arbuscular mycorrhizas (AM), which are endomycorrhizas in which hyphae form distinctive branched structures (arbuscules) in cells. In contrast, in ectomycorrhizas (ECM) the fungus ensheaths the outer surface of roots and forms a net-like reticulum between the cells of the root epidermis and the cells of the cortex. The link between plants and their fungal associates is known to go back to the dawn of life on land, and endomycorrhizas are among the first documented in the Early Devonian. The earliest well-documented fossils with diagnostic evidence for ECM symbioses are reported from the Eocene. I will present an overview of the current knowledge on fossil mycorrhizas including our recent findings from the investigation of the NHM slide collections.
For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html