Food security and climate change are among the greatest challenges for humankind’s long-term survival. The unequal distribution of wealth - including food wealth - has potential for global conflict over resources.
We aim to provide a comprehensive body of knowledge about mycorrhizal fungi in a single place. We begin by examining them in the context of the wider plant kingdom. Perhaps you are more interested in learning about their role in slowing climate change by boosting crops. In that case, you can skip the next section for now. Although you should visit it sometime to help you understand the process even better.
Fungi of various types are all around us.
Scientists used to call all types of fungus ‘plants’, because they thought they were rooted to a spot as the ones in the picture sure are Nowadays they are not so confident about their assessment, because in some cases fungi germ cells can actually swim. Now that is an intriguing thought: Fungus swimming in the bath! Let’s move to high ground and list the various types of fungus flourishing on our planet.
That was just an overview to get us closer to our main topic. We turn our attention to those mycorrhiza fungi living in a win-win relationship with vascular plants.
We move on to discussing how Mycorrhiza Fungi enjoy a beneficial mycorrhizae relationship with higher-order plants
The vascular group of plants includes the following species:
These wither and die when the soil dries out. Wise gardeners understand they need water at their roots, not on their leaves. To summarise briefly:
Vascular plants have water-carrying tissues enabling more vigorous growth
Vascular plants have specialized roots, stems and leaves to facilitate this.
A mycorrhiza is a process, usually beneficial and between certain fungi and vascular plants occurring via their root systems. This fungi process either occurs inside or outside the plant cells, depending on the particular fungus after it colonises the roots. Essentially:
Scientists originally classified the mycorrhizae fungi as either endotrophic (inside the root) or ectotrophic (outside the root. Nowadays they use a wider range to describe mycorrhizal types.
These are the commonest mycorrhiza type associated with 80% of plant types including many crops. Hence, they have greatest potential in our quest. The relationship occurs inside the root structure.
Ericoid Endomycorrhizas are on the outside of root structures and are less common, but better adapted to harsher environments such as moorlands. Typical mycorrhizae hosts include heathers and lings. There are two subsets to this mycorrhizal fungi category:
These are similar to Ericoid Endomycorrhizas, except the nutrition they provide is more suited to orchid plants. They are common in orchid growing mediums containing coconut husk, fir bark, sphagnum moss, and tree fern fibres.
Ectotrophic fungi are the most advanced in the classification, because they penetrate through the outermost cell layers forming a net. The structure then extends out to explore soil. They can spread between trees forming the ‘wood-wide-web’ as some call it.
Mycorrhizae fungi are clearly beneficial to plants, because:
Indeed, one could argue the food chain could nor develop without this natural process. Later, we examine its influence on
But first, let’s examine how the process works in more detail.
The mycorrhiza system provides a regular supply of carbohydrates as follows.
Indeed, a plant is incapable of absorbing nutrients such as phosphate on its own. The fungi also release other nutrients locked up in decaying wood, that plants would not be able to access in the shorter term.
Specialised mycorrhizae use a combination of physical processes and chemical absorption to increase the uptake of moisture.
The fine filaments (mycelia) in the gungi network are smaller in diameter than even the most delicate root hairs. Hence, they are able to explore soil material that plants cannot reach, detect moisture and nutrients, and absorb them through their relatively larger surface area.
The cell chemistry of the membranes of mycorrhizal fungi differs from plants.
These mechanisms make mycorrhiza fungus an ideal plant partner in moisture and nutrient deficient soils.
Plants associated with these fungi can often shake off diseases caused by microbial germs in soil. Their defences above and belowground are stronger, because the mycorrhizal fungus excretes enzymes that nematodes and other soil organisms find poisonous.
Arbuscular mycorrhizal fungi also correlate well with soil fertility on the biological level, relative to soil disease, bacteria, and fungi.
Johnson, David, Gilbert, and Lucy found the mycorrhiza process empowers plants to use their underground connections to send and receive warnings between other plants.
Plant colonization is the process whereby plants spread out and increase their collective productivity. This is essential for the survival of the food chain, and countering the greenhouse effect causing climate change.
We owe our existence to plants. After they migrated from water to land, they harvested nutrients from rocks to form original soils on which they and other life could settle.
The New Phytologist Trust hosted a symposium on the Colonization of the Terrestrial Environment in July 2016.
Researchers arrived from all over the world, eager to discuss how plants colonised land and how this affected Earth’s history. They produced a report how creatures crawled onto the land to feed on the progeny of a multicellular species of green algae, the grandparent of all plant life.
The New Phytologist Trust provides a handy guide to the summary appearing here.
Atmospheric oxygen became sufficiently dense half a billion years ago, to enable mammals to develop, and migrate throughout the planet. The Colonization of the Terrestrial Environment symposium determined this was due to photosynthesis by
There is a 400-million year old treasure chest called the Rynie Chert in the form of an intact sedimentary deposit in Aberdeenshire, Scotland.
Now we understand how arbuscular fungi helped kick start life, let’s turn our attention to what they could do to help feed the world, and help stop climate change in its tracks. Our far-reaching research continues as we explore these fascinating issues.
Climate scientists at the Stockholm Resilience Centre published a report in the first half of August 2018, warning Earth is nearing a ‘hothouse phase’. They are concerned about what will happen if global temperatures rise more than 2% above preindustrial levels.
They present a scenario in which the natural systems that protect us from the Sun’s heat run out of control. They warn the situation will stabilize ‘in the long term’. By then, global temperatures will be 4 to 5% higher than preindustrial levels.
All the surface ice on earth, in the glaciers and on the mountaintops will have added to the sea, with their power to reflect solar energy probably lost forever. Sea levels will be 10 to 60 meters higher than today. Much of the current coastline will be uninhabitable.
Climate change denialists say the Stockholm Resilience Centre report is exaggerated. That may be so, but what if it is true. Perhaps we should do something about it anyway. After all, we do seem to have entered a phase of severe weather events suggesting something is not working as it should. The Stockholm Resilience Centre suggests the following tipping points could act like a row of dominoes:
This is a complex model. The scientists say part of the solutions lies in growing more trees and plants.
The U.S. Department of Agriculture published a report on the drivers of improvements in global food security on August 21, 2018. They predict global food insecurity in low and middle-income countries should fall from 21% to 10% by 2028.
All Africa shared good news on 23 August 2018, concerning how Kenyan small-scale farmers are succeeding with crops of
Their success is lifting them out of poverty as they have enough left over to sell.
The role of mycorrhiza fungus in interaction with healthy plants comes sharply into focus when we consider what this could to Sub-Saharan Africa’s often arid and overworked soil. We need to introduce this where it is missing and educate the people about its role.
This fungus has been with us from the beginning. Yet many have neglected it, although it holds promise to alleviate these three global scourges.
Finally, we turn our attention to becoming stewards of the resource. How can we use it best, is it sustainable, what are the threats?
Glomeromycota are a separate division in the Fungi Kingdom. They are relatively unique it the sense of being able to form arbuscular mycorrhizas through penetrating vascular land plant roots.
However, they do face several risks. Your final takeaway from this article is to remember what these are:
Tilling the soil for agriculture or landscaping may introduce harmful bacteria that harm the microscopic organisms making up the fungi.
Soil erosion may carry away the fungi, harming the beneficial networks that enabled the original plant colonisation.
Irreparable damage to plants due to climate change is beginning to become a disaster if we do nothing.
Mycorrhizae Fungi are almost incredibly beneficial to our environment, by improving plant health through more efficient use of soil-based nutrients. We can restore desertified and degraded land by re-injecting them. However, what will happen if the world becomes too warm for them to sustain? Could this be the final tipping point for this series of dominoes?