Within this project I introduce a kit for capturing signals between plants (Fig. 1.). The kit includes components for an electronic interface capturing electric signals in plants and transducing them into the digital signals sent to the computer. The use of the kit is divided in a couple of phases. In the first phase the kit introduces cultivation of the mycorrhizal networks and plants using cardboard and Fungi spores. In addition the seeds of lettuce will be planted. During the second phase the kit will invite to build electronic interface and bridge it with mycorrhizal fungi and computer in order to follow the interaction of the cultivated plants.
How information is transferred within the living organisms
Like in all the matter, differently charged protons, neutrons and electrons of the atom generate electrical signals. As every solid, liquid, gas, and plasma is composed of neutral or ionized atoms, the proposed toolkit will introduce a possibility of reading signals within the environment including interconnected matter of different nature. This includes living organisms (plants and fungi), nutrition (cellulose, water) and electronic circuits.
The cytoplasm of plants or fungi has potassium (K) and Sodium (Na) salts, which provide the correct ionic environment for metabolic processes, and as such functions as a regulator of various processes including growth regulation. Potassium ions (K+) provide protein synthesis and interaction with the outer environment, for example exchange of gas or nutrition (Leigh et al 1984).
The “cell membranes practice a trick often referred to as the sodium-potassium gate. It's a very complex mechanism, but the simple explanation of these gates, and how they generate electrical charges, goes like this: At rest, your cells have more potassium ions inside than sodium ions, and there are more sodium ions outside the cell. Potassium ions are negative, so the inside of a cell has a slightly negative charge. Sodium ions are positive, so the area immediately outside the cell membrane is positive... When the body needs to send a message from one point to another, it opens the gate. When the membrane gate opens, sodium and potassium ions move freely into and out of the cell. Negatively charged potassium ions leave the cell, attracted to the positivity outside the membrane, and positively charged sodium ions enter it, moving toward the negative charge. The result is a switch in the concentrations of the two types of ions... This impulse triggers the gate on the next cell to open, creating another charge, and so on” (Layton 2008).
Background for plant communication
Fungi and plant kingdoms belong to the Eukariota domain and have eukaryotic type of cells which differ apart from prokaryotic cells (bacteria and archaea) in membrane-bound organelles, which contains the genetic material enclosed by the nuclear envelope. For this particular project I am interested in symbiotic relationships between fungi and plants. According to Nic Fleming “around 90% of land plants are in mutually-beneficial relationships with fungi. These partnerships are usually described as "mycorrhiza" where the fungus colonizes roots of the plant (Fleming 2014). The colonization is either intracellular (arbuscular mycorrhizal fungi), or extracellular (ectomycorrhizal fungi) where both sides interact to each other exchanging chemical elements and differently charged protons and electrons.
Most fungi grow as mycelium consisting of a mass of branching, thread-like hyphae, which are cylindrical, thread-like structures 2–10 µm in diameter and up to several centimeters in length. All together hyphae may form extremely large organisms, as for example Armillaria ostoyae, which occupies 965 hectares os soil found in US Oregon's Blue Mountains (Casselman 2007). While being able to form net-like structures, fungus is called as "Earth's natural internet” (TED 2008). Fungi expert Paul Stamens has even compared mycelium to ARPANET, the US Department of Defense's early version of the internet (TED 2008).
The exchange of chemicals within mycorrhiza where explored by Kathryn Morris, formerly Barto (Barto et al 2011), Nancy Stamp (2003) Rick Willis (2010). Morris with her team “tested the soil in the cylinders for two compounds made by the marigolds, which can slow the growth of other plants and kill nematode worms. In the cylinders where the fungi were allowed to grow, levels of the two compounds were 179% and 278% higher than in cylinders without fungi. That suggests the mycelia really did transport the toxins” (Barto et al 2011). “The team then grew lettuce seedlings in the soil from both sets of containers. After 25 days, those grown in the more toxin-rich soil weighed 40% less than those in soil isolated from the mycelia. ‘These experiments show the fungal networks can transport these chemicals in high enough concentrations to affect plant growth,’ says Morris, who is now based at Xavier University in Cincinnati, Ohio” (Fleming 2014).
As a result of this growing body of evidence describing the communications services that fungi provide to plants and other organisms, many biologists have started using the term "wood wide web."
Cut the cardboard into pieces that fit well into the petri dish or other sealable container (plastic one from the supermarket, glass container or any other dish resistant of boiling water and sealable with fresh foil will work). Stack them up inside and fill with boiling water. Soak for 10-15 minutes so the layers of the cardboard will separate easily. Drain then separate the layers so you have sheets of corrugated layers and sheets of flat card.
Take your Oyster mushroom and cut it into the small pieces (1 mm2 will work good). Only use the base as this is the reproduction part which will grow within the cardboard.
Add a plain and corrugated layers of cardboard to the bottom of the container. Place your oyster pieces on top and add additional layer of a corrugated sheet of cardboard, so the mycelium has space to grow. You can add as many cardboard layers as you want. Place on top of the cardboards couple of lettuce seeds. Close the dish with fresh foil leaving holes for air circulation. Store in a dark place at room temperature and inspect after a couple of days. Once the mycelium has reached a level you are happy with and the lettuce is grown enough to be attached to electrodes, it is a time to proceed with the second phase of the project.
Bridging plants and computer for scanning their interactivity
The part has been inspired by series of experiments conducted by Leslie Garcia within Pulsu(m) Plantae project (Garcia 2010), Martin Howse within radio mycelium: inter-species fungal communication (Howse 2012) and the scientific discoveries introduced above (TED 2008, Fleming 2014, Barto et al 2011).
Place the AD620 amplifier on the breadboard, with its legs bridging the middle gap. Connect the the 100 μF capacitor between pin 4 and pin 7. The capacitor smooths the power supply from the Arduino. Place the 1 kΩ resistor between pin 1 and pin 8. This resistor sets the amplification of the organism’s signal to a factor of 50. Add the two other resistors at the pin 5 (reference) with one ending at pin 7 (power) and the other at pin 4 (earth). This sets the ground reference for the amp. The pin 7 is then connected to the power and the pin 4 to the ground of the Arduino board. The analogue input A0 of the Arduino board is connected to the pin 6. Pins 2 and 3 of the amp are connected to two different plants (Landwehr & Kuni 2013).
Connect the Arduino board to the computer using the provided USB cable and set the port and the board in the Arduino preferences (install the provided software if it is not yet installed). Load standard Firmata sketch into the Arduino board. If not yet available, install the extended version of Pure data and its piduino plugin. Open the provided AnalogIns sketch. Turn on the select box of the sketch (if you do not know which port listens to the Arduino board, let the sketch print it by clicking on “Devices”). Activate the “toggle” box of the sketch so the sketch updates the values captured on the Arduino box. If everything is done correctly, the scale at the bottom of the patch should start moving left and right. The changing values could be sonified or visualised.
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- Stamp, N. (2003. "Out of the Quagmire of Plant Defense Hypotheses" in The Quarterly Review of Biology 78: 23–55. Available at http://homepages.wmich.edu/~malcolm/BIOS5970-Plant-Herbivore/Publications/12%20Stamp-QRevBiol2003.pdf (Accessed 25 May 2016).
- TED (2008) 6 ways mushrooms can save the world. Available at: http://www.ted.com/talks/paul_stamets_on_6_ways_mushrooms_can_save_the_world (Accessed 8 November 2015).
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