Introducing some information informed regeneration tactics, evolutionary relationships between plants-fungi, and their importance to us: beginning with endomycorrhizal fungi, our rarely praised ubiquitous plant penetrating friends.
Here I lay out some of the basics around the plant/fungal relationship ascribed by the word mycorrhizae. To start, an extremely brief overview on plant biology.
Plant bodies differentiate into two polar structures called shoots and roots. Shoots consists of the wood, flowers and greenery we all are familiar with. They serve as an interface with the above ground world. As well as allowing human civilization (future topic I’ll get to), their basic functions range greatly from processes such as photosynthesis (sugar production driven by light powered water splitting), reproduction (seeds, fruit, spores) and social exchange of nutrient/information. Essential to these operations is the ability to integrate and respond to a diverse set of environmental signals. To control responses, roots and shoots influence each other through chemical and non chemical signaling mechanisms.
The other half of the plant body are the root systems, essential connectors and anchors. They source nutrients and water so the entire plant can maintain vitality and develop structure (not accomplished alone as we will see). Sensing and managing responses to nutrient/mineral/water gradients, microbe relations and soil structure also fall under their domain. Roots, just as with shoots, integrate information from its environment and makes decisions.
From what I have read, no one quite understands how plants represent their experiences/stimulations internally, well... no one from western science at least.
Now to the fungal aspect. Fungi represent their own kingdom of life (maybe more precisely queendom) of life. Much like the distinctions we make between plants and animals, fungi require their own distinction. The vegatative “body” consists of microscopic branching threads known as mycelium. Sexual reproduction often comes in the form of a fruiting body (think apple or berry) known as mushrooms. Commonly I hear people refer to mushrooms as plants, or as the fungus itself, but it's useful to remember that mushrooms are the sexually derived reproductive structure of the fungal organism, below is a decent example to see how mycelium and the subsequent fruiting body relate
The white threads below this mushroom is the mycelium from which its derived. Under the cap lies millions of genetically distinct spores. Few will find a suitable habitat and begin to grow as mycelium, hopefully finding suitable mates and repeating the process.
(image my own)
Vastly increased water uptake, nutrient acquisition/exchanges and signaling with other mycorrhizal networks entail some of the principal functions of the plant-fungal relationships. The fungi’s small refined branching structures called mycelium allow for deeper access within soil matrix. Increased water acquisition and nutrient assimilation in poor soils are among the often touted benefits of MF. Plants donate (or are coerosed, the language gets tricky) carbohydrates (food) to the fungi in exchange for the above benefits. Networks of these organisms emerge from the fungi’s ability to fuse growing tips. While the relationships and mechanisms are not profoundly understood, through radioisotopic marking methods we know nutrient and other chemical exchange occurs between related and unrelated plant species. Below is a relatively iconic image of a young pine inoculated with a mycorrhizal fungus (the white stuff)
Scientists are slowly uncovering this social networking behavior and the innumerable intricacies within. Broadly nearly all scientists consider it a symbiotic relationship, yet observed experimental data complicates a simple picture when considering the question of symbiosis or parasitism, but for introductions sake it works. A lack of adequate concepts is a recurring theme with the analysis of plant-fungal-ecological relationships.
Now the basic classifications and mechanisms behind mycorrhizae. Arbuscular Mycorrhizal Fungi (AMF) engage with over 90% of terrestrial plants, thus nearly ubiquitous among diverse terrestrial ecosystems. AMF are a specific expression of endomycorrhizae, involving the formation of arbuscules within cortical root cells. Nutrients and other organic material is transferred there. The actual penetration of root cells distinguishes AMF from other mycorrhizae such as ectomycorrhizae, which do not penetrate roots cells. Cortical cells exist outside the primary vascular system (vascular tissue transports stuff), which occupies the center of the plant body, but are deeper than the bark (epidermis or periderm) layers.
Worth keeping in mind that AMF is a single type of fungi-plant root association. Other types of mycorrhizal associations exist, such as orchid mycorrhizal, which plays an instrumental role within the life cycle of every single orchid. The family Orchidaceae comprises one of the largest families within the umbrella of flowering plants (angiosperms). Ecto and endo mycorrhizae are two other types of association that i”ll largely ignore today.
If you made it this far yay, here's a hug.
So naturally some may wonder how the hell did all this stuff develope? What was the starting point and how did these relationships govern themselves through much time and space? Very recent research shows that fungi may of been one of the first organisms to survive on land https://www.nature.com/articles/s41586-019-1217-0#Abs1. Other current research suggests that lichen-like (alge/fungi symbiosis) organisms paved the way for soil formation to further drive land colonization and increasing complexity of the plant body. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744040/ is a favorite article that goes deeper into the hormonal mechanisms that stimulate increasing complexity in plants. The currently proposed evolutionary relationships give context to how essential this ancient relationship in the development of terrestrial life. Understanding these essential yet often ignored relationships may revel to be paramount in reinvigorating destroyed soils (Asmelash, Fisseha et al).
Mounting evidence in support of plant cognition changes how we categorize and analyze these systems. The ability to learn by association, once thought to be unique to the animal kingdom, has been experimentally demonstrated (Gagliano, Monica et al). This means that plants can associate arbitrary signals with some other stimuli and judge their situation accordingly. This process is essential for learning, developing mental (for lack of a better word) model. Recently, the reality of plant cognition has hit scientists hard, deciphering the foreigen mechanisms has proven difficult and controversial. Search plant neurobiology to see many back and forth debates around plant cognition. Further inquiries in that area require alot more information that future writings will explore.
Broadly, a fascinating situation emerges when considering the difference between the diversity and quantity of signals received by plants and animals. Plants do not move, yet have remarkable sensory abilities and internal controls. Feel free to explore that field further. This post was quite decent https://thequietbranches.com/2015/01/26/plant-senses/. Take note that I am only talking about plants. As we recently learned plants do not operate in a silo, (nor does anything! Learn about humans microbiomes!) and lean greatly on their ancient relationship with fungal friends/invaders. Which organisms integrate what signals and how do they pass this information to each other? Unfortunately there is even less research on fungi, so these questions require more observation and experimentation.
Currently many modern industrial farming methods neglect these relationships and opt for strategies that priorities short term yields. This pattern leads to little longevity. The forestry industry understands the importance of this relationship, many tree species wont grow without mycorrhizae. Land regeneration techniques dont ignore the fungal aspect anymore. I expect the knowledge base to continue to rise in accordance to this.
Studying the subtleties of these relationships can give soil practitioners a basis point in terms of what relationships to nurture in the soil ecosystem. Evidence exists that MF aggregate soil particles into a structure that better promotes root growth. Soil structure and its influences on characteristics such as water retention is of utmost importance to land use managers.
The general case for bioregional approaches to land management is compelling, however we can not neglect the consequences of industries/practices of other areas, clearly globalized society affects everywhere to complex, differing degrees (Asmelash, Fisseha et al). Adaptations may be necessary to respond congruently for the dynamic realities of our current civilization.
Many aspects to consider for future analysis. I’ve noticed fascinating correlations between the decentralized crypto community and the networks plants/fungi form. Network intricacies developed over a billion years may yield useful insights for the people considering technological networks structures.
Thanks for reading, more to come!
Image
https://www.slideshare.net/martyynyyte/plant-organ-cross-sections
Cited
https://www.nature.com/articles/s41586-019-1217-0#Abs1
Asmelash, Fisseha et al. “The Potential Role of Arbuscular Mycorrhizal Fungi in the Restoration of Degraded Lands.” Frontiers in microbiology vol. 7 1095. 26 Jul. 2016, doi:10.3389/fmicb.2016.01095
Gagliano, Monica et al. “Learning by Association in Plants.” Scientific reportsvol. 6 38427. 2 Dec. 2016, doi:10.1038/srep38427
Baluška, František, and Stefano Mancuso. “Microorganism and filamentous fungi drive evolution of plant synapses.” Frontiers in cellular and infection microbiology vol. 3 44. 15 Aug. 2013, doi:10.3389/fcimb.2013.00044 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744040/
