Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of what we’ve learned about fungi from November 2016 Through February 2017. Read below to learn about: bacteria-fungal interactions, snake fungal disease, psilocybin research, fungal furniture, white-nose syndrome, intelligent slime molds and more! Visit the associated links to get the full story.
fungus-plant root symbioses
Arbuscular mycorrhizae have been around since plants began to colonize the land and were probably instrumental in that transition. Ectomycorrhizae and ericaceous mycorrhizae evolved during the time of the dinosaurs and were successful because of their ability to extract organic nutrients from the well-defined soil. Orchid mycorrhizae were the last to evolve. This probably happened around the same time as mammal lineages started to diverge. Despite the tens to hundreds of millions of years of symbiosis, coevolution does not appear to play a large role in the evolution of modern mycorrhizal partners.
Many plants in the order Ericales (which includes blueberries, rhododendrons, heaths, heathers, tea, and Brazil nut) form unique mycorrhizae. These plants are frequently found living in harsh conditions, like acidic or highly acidic soil. Their aptitude for these types of habitats is likely due to their unique mycorrhizae. There are actually three types of mycorrhizae formed by these plants: ericoid, arbutoid, and monotropoid.
Orchid seeds do not contain sugars, so the seeds take sugars from a mycorrhizal fungus. All orchids are parasitic on fungi while they are seedlings. Because of this unusual relationship, orchids form unique mycorrhizae that differ from both ecto- and arbuscular mycorrhizae.
Ectomycorrhizae are mutualistic relationships formed between trees and fungal species in both the Ascomycota and Basidiomycota. The main difference between ectomycorrhizae (abbreviated EM or ECM) and arbuscular mycorrhizae (discussed last week) is that in ectomycorrhizae the fungus never penetrates the host plant’s cells.
Generally speaking, mycorrhizae are mutualistic interactions between the hyphae of a fungus and the roots of a plant. In most cases, the plant gives the fungus sugars in exchange for hard-to-get nutrients like nitrogen and phosphorous. Although there are exceptions to these rules, fungi that are described as “mycorrhizal” usually in the manner described above.