Les séminaires de l’ISYEB - Florent Martos, ISYEB

Since the pioneering works by Noël Bernard, scientific interest in orchid mycorrhizas has continued to grow. This might seem somewhat surprising as the association concerns a single angiosperm family and is less widespread among land plants than the arbuscular mycorrhizal symbiosis. Impetus for research into orchid mycorrhizas has been multifaceted. As the earth’s largest flowering plant family, accumulating basic biological knowledge of what represents approximately 10 % of the angiosperm diversity is justified. For the mycologist, these plants that shifted from an ancestral symbiosis with Glomeromycetes to an original symbiosis with new fungal partners offer a window on mycorrhizal abilities in numerous, and sometimes unexpected, fungal lineages. Illuminating studies of orchid mycorrhizas have shown that heterotrophic (achlorophyllous) orchids live as parasites on ectomycorrhizal interactions and that green orchids (most of the species) largely associate with the ‘rhizoctonia’ fungi. But recent research has given insights into the nature of the mycorrhizal associations of heterotrophic and autotrophic orchids in tropical ecosystems. The mycorrhizas of orchids also offer general perspectives on the evolution of specificity and mycorrhizal networks among plant…