05: Missing Link

Phytometallurgy for dummies (as you put it)

To: Willard Syse
03 March 2153, 10:33AM

Good morning Director!

Today I am very excited. I appreciate your renewed interest in hearing about our progress. I understand that trying to wrap your mind around our field of research can be a bit challenging. I, myself, am also constantly learning new things that I must spend time comprehending, not only in my own branch of science but from all of the other brilliant minds here in Rebourne. We must be thankful to be in such a rich and knowledgeable environment!

My goal is to hopefully give you a layman’s explanation of our work in hopes that you will be able to relay the information to the necessary sources in the near future. So I will try to explain things in terms of how they relate to our current goals with LOAMA and hybridization. With Dr. Kahnwald and her team slowly producing the infantile structure of LOAMA and showing us how it might behave amidst LEAF and the plants, having a better grasp on what we are doing in phytometallurgy is definitely imperative, especially when the time comes for us to begin trialing different species’ lignin compositions. I hope the other teams show as much enthusiasm as you. I will be waiting patiently for their eager minds (not for too long, I hope!). Now let us begin!

Phytometallurgy and Our Current Methods

As I’m sure you know, at the basic level phytometallurgy studies the physical and chemical interactions and compatibility between plants and metallic elements. With this knowledge we have been able to optimize the robotics integrations of specimens to ensure long-term compatibility and structural integrity, as well as minimize any sort of risk that might come from the exposure to certain metals or from the actual integrations themselves.

To help organize and analyze this data, we use our handy Species-Metal Affinity Atlas. This is a large-scale catalog of all the tree species we have experimented with and their tolerance/reactivity to various metals and composite materials. Really it is us attempting to play matchmaker and find out which plants are most compatible with specific metals. We also track changes in sensitivity over time between plants and metals, both in singular specimens as well as many specimens of the same species.

Interestingly, we have seen success in adapting singular specimens to different metals using exposure therapy. This usually involves us grafting a powdered form of a metal onto a small section of stem where we’ve exposed the cortex. This is also the method we use to get initial data for a species concerning their tolerance and reactivity to different metals.

We’ve also managed to increase tolerance in a species overall by taking a specimen that we’ve conducted exposure therapy on and propagating it into new individual plants. These new specimens will often largely retain the affinities of their parent, needing much less exposure therapy than a specimen grown from seed. That being said, we do still grow many specimens of the same species from seed and perform exposure therapy on them individually; this way the gene pool remains more diverse and decreases the risk of inbreeding depression (an increased risk of inheriting harmful genetic traits due to low diversity). And it gives us more data, which is always a good thing!

Ion Leaching and Phytometallic Exchange

Now, at the heart of all this data is the concept of ion leaching. There are many different types of ion leaching, but it always refers to the dissolving or extraction of atoms or molecules from a solid into a surrounding medium. In the world of plants, the most common example of this is when rainwater leaches minerals and nutrients from soil or leaves. There are also other subcategories of leaching in plants, such as when plants perform exosmosis and move materials outward from their tissues under the influence of osmotic forces (think of a grape being placed in a more concentrated solution like sugar/salt water which then causes it to lose water/minerals, shrink, and become a raisin.)

Another subcategory of ion leaching is one that we use and study here in Rebourne, specifically the leaching between plants and metals, which we refer to as phytometallic exchange. When we integrate robotics modules into specimens, we have to keep in mind the different elements that make up the modules. Plants are ion-sensitive systems. Things like nutrient uptake and stress responses all depend on regulating specific ions such as calcium, magnesium, potassium, nitrate, phosphate, and many more. That means that we need to be cautious about what types of metals we are integrating to each species since certain metals might contain some of these precious ions. While we do our best to utilize corrosion-resistant materials, inevitably some type of leaching always occurs, even if it is very slow. This might occur via rainwater runoff as I previously mentioned, through exosmosis at the integration point (water trying to move from the plant where it is more highly concentrated, to the metal of the module where it is less concentrated), or simply through oxidation over time, leading to the spread of ions into the connected plant tissues or root systems within the soil.

Some of our modules such as the NutriTap or our more recently developed Volt in collaboration with LEAF feedback have allowed us to adjust and respond to certain ion readings to optimize plant growth or avoid stressing specimens, but we have done our best to not overrely on them and simply try to play matchmaker, finding the best metals and modules suited for each species before doing any kind of heavy integration. Very romantic!

Up to this point in our work, our primary concern has been leaching from the metals to the plant. While we can have our robotics measure and regulate the ions of our plants, the risk of those ions leaching into the modules and causing issues has been relatively nonexistent. We have always safeguarded against such a thing, and, at most, we might experience a bit of mineral buildup at the integration points due to the exosmosis that I previously mentioned. It could potentially become a problem after so much corrosion or oxidation, but that would take many, many years, and at that point we would probably have already removed or replaced the module anyhow.

Toward True Hybridization

But now this is where things get even more interesting!

We have now worked our way to our current goals: achieving hybridization between plant and metal. And this is where it now becomes more vital to research and understand phytometallic exchange going both ways. No longer are robotics a mere addition to the plant, but the two are becoming one, each side sharing its ions with the other in a mutualistic relationship, hopefully becoming greater than the sum of its parts.

As you know, LOAMA is based on the makeup of lignin, which is the key to structural integrity and rigidity of plants. This is a fantastic reason to make it the center of translation between LEAF and the plant, as being able to alter the supportive foundation of a plant appears to be a great way to reinforce and safeguard further mutations. I only say “appears” because there is still quite a bit of research to be done, and we must see it play out in reality. But for all intents and purposes of this email, we will assume this is the way it will be done.

Now, while lignin is key in the structure of plants, it also serves another important purpose. You see, while plant cell walls are hydrophilic and attract water, lignin is hydrophobic, thus acting as an efficient transport network for water and nutrients throughout plants. In fact lignin is present in all vascular plants, but not in mosses, showing that the original function of lignin was restricted to water transport!

Because of lignin’s role in water and nutrient conduction, this makes it all the more important when it comes to ion leaching. If we can alter a plant’s lignin structure, we can further optimize its retention and transportation of certain ions throughout its roots and shoots. And, with the help of LEAF and LOAMA, utilize those ions to develop robotic mutations that will allow the plant to organically acquire some of the tools currently represented in our integrated modules. This will, hopefully, lead to an increased pace of adaptation that is able to keep up with the quickly changing environment and climate, ensuring the survival of these organisms.

This is probably excess information, but as a fun (and relevant!) side note, this all very much comes into play when we talk about the Casparian strip. The Casparian strip is a ring-like wall in the endodermis of plant roots, right outside the vascular tissue. Largely composed of lignin, it serves as a gatekeeping barrier to regulate the movement of water and nutrients into the plant, in addition to keeping pathogens and unnecessary things from entering. This gives the plant more control over what passes from the soil to the stems and leaves. It’s already true that a plant’s anatomy can adapt to the presence of heavy metals in soil, so we expect the ability to edit lignin structures and cross-communicate through LOAMA will provide even more wiggle room and opportunity for those adaptations, especially when thinking about harnessing the power of a part like the Casparian strip.

Going the other way, with the metallic mutations in place, we can then once again think about ion leaching from said mutations to the plant, but this time in a bit more positive light. Before, due to their “unnatural” nature, we had to worry about the ions of our integrated modules leaching into the plant tissues and causing imbalances that worked against our goals. But now, because those metals will be natural to the plant, it will already have the wherewithal to regulate and respond to any leaching that might occur, whether by external or internal force. And, though I might be speaking a bit too optimistically, the plants might even be able to recycle individual ions (or even entire metallic parts!) into extra nutrients and building blocks for whatever growth and survival purposes it and LEAF see fit!

But on that exciting note, I believe I have covered everything I intended. I apologize for taking the scenic route to get to our current work, but it all seemed necessary in order to make sense of it all. Maybe not as much “for dummies” as you would have liked, but if you have any questions, please do not hesitate to ask!

Happy learning,
Eelco