Behind the Cover: New Phytologist 215:4, September 2017

Fungal friend, or foe?

In this issue of Behind the CoverNew Phytologist Editor Ian Dickie explains the complicated role of the mushroom gracing the cover of issue 215:4.

Amanita muscaria, or fly agaric, is one of the most iconic of fungi: it is the classic mushroom of fairy tales and children’s cartoons. Native to the northern hemisphere, it has become a widespread invasive throughout the southern hemisphere. When associating with northern hemisphere pine trees (Pinus nigra or Corsican pine in this picture), it is a classic case of ‘co-invasion’. However, Amanita muscaria can also form ‘novel associations’ with native trees such as Fuscospora cliffortiodies (mountain beech), or ‘co-xenic novel associations’ with alien trees from outside the natural distribution of Amanita muscaria, including Eucalyptus species (gum trees) from Australia.

Despite being one of the most photogenic of invasive alien fungi, Amanita muscaria probably plays a relatively minor role in facilitating pine invasion. Amanita is generally considered to be a ‘late-stage’ fungus, primarily infecting trees once they are several years old. As such, it may play a large role in the impact of pine invasion on ecosystem function, but is unlikely to drive the actual invasion front. We are presently working on confirming which fungi are present at the earliest stages of invasion: our primary suspects are Rhizopogon and Suillus, both of which can be animal dispersed and potentially persist in the soil, but Thelephora or Tomentella may also be important. None of these fungi are nearly as attractive as Amanita, however.

Image: Ectomycorrhizal Amanita muscaria emerging through litter of its co-invading symbiont, Pinus nigra, in New Zealand.
Ectomycorrhizal Amanita muscaria emerging through litter of its co-invading symbiont, Pinus nigra, in New Zealand.

One particularly important aspect of Amanita muscaria is when it forms novel associations with native trees, the effects of which remain almost entirely unexplored. We know that alien fungi often produce many more and larger fruit bodies in an alien range than in their native range, which suggests some shift in carbon dynamics. Nonetheless, as of yet we have little understanding of the effects of these alien fungi on native fungal communities, native plant physiology, or soil ecosystem functioning. These are key areas for future research. We also need to demonstrate that fungal invasions can be controlled, or that understanding fungal invasions helps manage linked plant invasions, if we wish to justify further research.

This particular picture was taken at a site where we are examining the impacts and post-removal legacies of Pinus nigra invasion on ecosystem functioning. It was taken at the end of May, which is very late in the year for finding good mushrooms to photograph in New Zealand. Amanita has a very extended period of fruiting in its alien range, but when nights are below freezing the mushrooms tend to collapse into pools of slime. I had been looking for a good specimen most of the day. I finally found this particular specimen in the mid-afternoon while walking between plots. I suspect it may have emerged from the ground that morning, as there had been a heavy freeze the night before. No special equipment was used, I just lay down on the ground with my iPhone to get an angle showing the veil and gills.

There are a few blades of grass in the picture, which is actually quite appropriate. One of the main things we have found in pine invasions is that they tend to favour subsequent invasion by alien grasses. I had hoped to get a photograph that would include a rust fungus on a grass, which would have tied into the pathogen part of our Tansley Review, but unfortunately this appears to be a healthy specimen. The reader will just have to imagine that it is seething with endophytes and latent pathogens…

Ian Dickie
Editor
New Phytologist

Read the paper:

Dickie, I. A., Bufford, J. L., Cobb, R. C., Desprez-Loustau, M.-L., Grelet, G., Hulme, P. E., Klironomos, J., Makiola, A., Nuñez, M. A., Pringle, A., Thrall, P. H., Tourtellot, S. G., Waller, L. and Williams, N. M. (2017) The emerging science of linked plant–fungal invasions. New Phytologist. doi: 10.1111/nph.14657

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