Friday, February 16, 2018

Northern Arizona University: Mycorrhizal Fungi boost nutritional value up the Food Chain

Plants, and bacteria, and fungi! Oh My!
Image - Wanderlust Travel

Nancy Johnson collecting soil samples in the Serengeti
Nancy Johnson, an Northern Arizona University ecology professor, contributed field samples to a global-scale study of the biogeography of Arbuscular mycorrhizal fungi, also known as AM fungi. Johnson is listed as an international co-author on the paper. These fungi support 80 percent of plant species, including crops, by capturing nutrients from soil. Johnson said understanding how different species of AM fungi are distributed around the globe is important because of the vital roles they play in the ecosystem. These researchers gathered 1,014 fungi samples from six continents, and what they discovered was surprising. “Our study suggests that most species of arbuscular mycorrhizal fungi are found all over the world, which is rather unusual among organisms,” Johnson said. “The question is, how do they get everywhere?”
Abstract: The global biogeography of microorganisms remains largely unknown, in contrast to the well-studied diversity patterns of macroorganisms. We used arbuscular mycorrhizal (AM) fungus DNA from 1014 plant-root samples collected worldwide to determine the global distribution of these plant symbionts. We found that AM fungal communities reflected local environmental conditions and the spatial distance between sites. However, despite AM fungi apparently possessing limited dispersal ability, we found 93% of taxa on multiple continents and 34% on all six continents surveyed. This contrasts with the high spatial turnover of other fungal taxa and with the endemism displayed by plants at the global scale. We suggest that the biogeography of AM fungi is driven by unexpectedly efficient dispersal, probably via both abiotic and biotic vectors, including humans.


The complex Serengeti ecosystem, which spans 12,000 square miles extending from northern Tanzania into southwestern Kenya, is home to millions of animals, including 70 species of large mammals. It is a hotspot for mammal diversity—including herbivores such as wildebeest, zebra and gazelles that graze on grasses and trees, as well as lions, crocodiles, leopards and hyenas that survive by preying on the grazing herbivores.  

(New Study) published in the Journal of Ecology by a team of Northern Arizona University researchers shows the food web supporting this remarkable variety of wildlife would appear very different without the nutrients supplied by arbuscular mycorrhizal (AM) fungi. The interdisciplinary study, authored by graduate students in NAU’s School of Earth Sciences and Environmental Sustainability  —Bo Stevens, Jeffrey Propster, Andrew Abraham and Chase Ridenour—along with assistant professor of informatics, computing, and cyber systems Christopher Doughty and Regents’ Professor of Earth Sciences and Environmental Sustainability Nancy Johnson, quantifies the importance of AM fungi in the soil of the Serengeti National Park in Tanzania.

Illustration by Victor Leshyk

Artist’s depiction of the Serengeti food web with normal AM (left)
 and a hypothetical food web without nutrient inputs from
 these important symbioses (right).

AM fungi, a type of mycorrhizal fungi, penetrate the roots of grasses and other plants native to the Serengeti. Considered natural biofertilizers, AM fungi provide their host plants with water, nutrients and pathogen protection in exchange for photosynthesis. The symbiotic relationship between AM fungi and plants, which has evolved for millions of years, is critical for the uptake of essential plant nutrients such as phosphorus. In turn, the nutritional quality of the plains’ grasses and trees influences the biomass of the herbivores and their predators.  

By creating an ecosystem simulation that enabled the researchers to measure the biomass of AM fungi across a natural soil fertility gradient and estimate the contribution of mycorrhizal symbioses to the biomass of all plants and animals in the Serengeti, the researchers were able to estimate the animal biomass that results from phosphorus supplied to plants through AM fungi.  

This study shows the contribution of mycorrhizal symbioses to the growth and nutritional quality of grasses cascades through the biomass of large grazing mammals and their predators. Although AM fungi amount to less than 1 percent of the overall living biomass in the Serengeti, their predicted nutrient inputs into the food web doubled animal biomass.  

“It’s really surprising that a small group of microbes can have such a large impact on an entire ecosystem,” said Stevens, lead author of the study. “We always knew that mycorrhizal fungi were important for grass nutrition in the Serengeti. Now we can say how important they are for the nutrition of animals up the food chain, from zebras to lions.”
"The answer my friend is isn't blowing in the wind"
Image - Roeselien Raimond

Image - Earthcrew Inc
The main subject of this research was certainly mycorrhizal fungi, but not the type that produces truffle or mushroom formation that we are used to seeing. This fungi was endo-mycorrhizal fungi which produce large propagules which don't necessarily move through soil pores as easily as the tinier microscopic spore of the ecto-mycorrhizal truffle which can explode with a cloud of brown powder we see in real life. This spore dust can even travel for miles and land in numerous places along the way. These spores are so tiny that they can move and be washed downward into the soil during rain storms where roots can make contact and colonize. But not the propagules of endo-mycorrhizal. Personally I always thought their movement was facilitated by animals like pocket gophers, maybe various insects etc. But this research was still interesting given that we accept endemic species (plants, animals, birds, fish, etc) around the globe to specific geographic locations, but many of these same identical endo-mycorrhizal species apparently are everywhere around the globe. How did that happen ??? 😲 Given that they don't exactly blow in the wind like all the exploding puffball ecto-mycorrhizal spores, how do they move and travel ??? Maybe it's the soil scientists doing it with their field trip sample collections 😄

Take this species of endo-mycorrhizae in the photo at left here is found in most popular commercial Mycorrhizal inoculent blends offered by many companies. Glomus deserticola fungi are found everywhere around the globe, even Siberia. I assume it was given the name because it was first recorded and given the name from it's first documented location in the southwest. It's an important fungal species, because they are found in nearly all terrestrial habitats, including arable land, deserts, grasslands, temperate, boreal, tropical forests, and tundras. Anyway the mode of movement is still very intriguing and fascinating. Next time you hear someone recite an old chant of, "You don't need to inoculate because the spores are just everywhere out there in the air," don't believe them. Inoculate anyway. 😉 Now, let's consider another important possibility of spore travel that the researchers mentioned above left out.
NASA Earth Observatory: "Smoke's Surprising Secret"
credit: US Air Force photo
 Forrest Mims II is a very well known, "Citizen Scientist," who had no formal academic training in science. And yet Forrest Mims has had a successful career as a science author, researcher, lecturer and syndicated columnist. His series of electronics books sold over 7 million copies and he is widely regarded as one of the world's most prolific citizen scientists. He does scientific studies in many fields using instruments he designs and makes and he has been published in a number of peer-reviewed journals, often with professional scientists as co-authors. Much of his research deals with ecology and environmental science. A simple instrument he developed to measure the ozone layer earned him a Rolex Award for Enterprise in 1993. In December 2008 Discover named Mims one of the "50 Best Brains in Science." But's it's Forrest Mims' daughter who steals the show here with her simple experiment on how fungal spores can travel great distances which is related to the subject I'm posting here. It's ashame the researchers never referenced this important experiment published by NASA.

(Image by Mark Gray, GSFC)

(Photograph by Forrest M. Mims III)
Sarah Mims, a teenager from Seguin, Texas, studied how smoke and dust that arrived over her hometown from thousands of miles away from Mexico's. By her senior year in high school, she had already made some surprising discoveries. This Satellite image from the days Mims conducted her experiments revealed smoke from fires in Central America flowing over the Gulf of Mexico and into the Texas sky. Blue-gray smoke stretches from the bottom center of the image toward Texas at the upper left. The bright region extending towards the top of the image from the Yucatan Peninsula is the sun glinting off the ocean’s surface. This image was acquired by the Moderate Resolution Imaging Spectroradiometer. 

(Digital Scans by Sarah A. Mims)
Sarah Mims exposed Petrifilms that you see in the photo above outside of her Texas home in April and May of 2002. She was expecting to find micro-organisms carried by Asian dust. Instead, colonies of bacteria and mold (right) grew on days when the air was filled with smoke, not dust. Under a microscope Sarah Mims found fungal spores along with chunks of black carbon or the individual particles of smoke. Once she knew the micro-organisms were associated with smoke, not dust, she needed to find their source and that's wheere NASA's satellite images helped pinpoint the source of the smoke. So this is yet another travel means of microbes globally. How endomycorrhizal propagules reach the soil surface from underground is another mystery. Still, this is interesting.
Earlier Relevant References on the same subject from the Northern Arizona University
(Image courtesy Victor O. Leshyk)
"Ectomycorrhizal fungi (the mushrooms connected to the roots of the tree) increase the uptake of nitrogen by the plant, even when that nutrient is scarce in soils. Arbuscular mycorrhizal fungi (associated with the grass roots on the left) do not provide that advantage to their host."
NAU’s Hungate co-authors research report published in ‘Science’

Credit: mdd/Shutterstock
Study of Serengeti soil may provide model for increasing productivity of croplands in U.S. (2011)
Mycorrhizal Fungal Blend Producing companies

Mycorrhizal Applications Inc

Image - Valent

Valent: MycoApply® EndoPrimeTM

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