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It's hard to justify having the word extreme twice in a title, but plants are generally underappreciated for their extreme nature. Under stressful environments, plants are often still found in ubiquity.
Just yesterday I was scrolloing around the outback of Australia on Google Maps (as you do) and found a small town of 200 or so people called oodnadatta:
Surrounding it is thousands upon thousands of square miles of... shrubbery, seemingly not a drop to drink the entire area. Other parts seem to find curious patterns like this intriguing path, presumably a dried up riverbed, and an outlier or some kind of pathetic oasis:
One can't help but wonder how they actually survive there - and this is no trivial question. Plans that can survive in highly stressful environments can be particularly useful for genetic modification of crops designed to withstand extreme conditions such as droughts, floods, heatwaves and so forth.
Uncommonly, such plants are known as 'Extremophytes' and they're arguably more important than the cliche tardigrades and Archaea we're always hearing about, and often come up with more novel solutions to their situations than you could imagine.
Metal-eating plants
Minerals are a staple part of a plant's diet, but if the soil becomes too saturated with heavy metals it can quickly become deadly - have you ever tried eating lead? Probably not given that you're reading this.
But some plants manage to overcome this and survive in extremely metal-rich environments. As recently as 2014, one plant Rinorea niccolifera discovered in the Philippines was found with up to 1000 times the amount of nickel in its leaves (18,000ppm) as would normally be safe.
In total, as little as 450 species are known to be able to tolerate these conditions, and scientists were quick to surmise their practical applications.
Phytoremediation
By using these plants in contimated soils, they could act as a kind of clean-up agent in a process called phytoremediation.
Traditional remediation techniques typically make contaminated soil infertile or otherwise unusable - just free of various pollutants. Atop that, they're expensive and limited, such as ‘pump-and-treat’, in which groundwater is pumped into a treatment system, and ‘dig-and-dump’ which as you might expect, is where you dig up the contaminated soil and dump it elsewhere.
Something elses needed to be done, which is where phyto, or bioremediation comes in; it's low cost, solar powered, can treat broad ranges of contamination and is effective.
Phytomining
More outlandish-sounding but very real is the process of phytomining, which is pretty much what it sounds like. Hyperaccumulating plants are put into soils with, say, copper content that we want to extract, then all one has to do is burn the plants, leaving the minerals behind in the pile of ash to be separated via electrolysis (not the most energy efficient process...)
How and Why do they do it?
What I imagine metallifefrous soil looks like
It isn't just us humans dumping contimated produce all over the place. Soils around the world are naturally metalliferous and often barren as a result, but this leaves a niche for the hardy.
The benefit for plants surviving here is two-fold; they dominate a niche environment that would be toxic to any competition, and they deter herbivorous wildlife who would otherwise try and eat them if not for the regrettable night in the bathroom that would follow such a meal. This works for pathogens and other hungry, unwelcome microbes too.
Toxic defense in plants is hardly unheard of, and as they say, 'you are what you eat' right?
According to a review by Robin S. Boyd, two hypothehses seem likely:
- The Defensive Enhancement Hypothesis.
This is simply an arms race, in which a plant had some success with comparatively low doses of metallic elements in deterring herbivores, and over generations inreased that concentration as evolution drove things forwards.
- Joint Effect Hypothesis.
This involves a synergy between elemental (inorganic) toxic effects and organic chemical defenses. By mixing metal and organic compounds, you get a new cocktail of toxins to experiment with, and is shown to be ecologically effective even in lower doses than these typical hyperaccumulative plants.
The process of accomplishing this is mostly unknown as far as I can dig up, but it involves several gene families, largely including the ZIP family, which is capable of transporting numerous metals including Zinc, Iron and Cadmium.
It's the job of modern research to isolate where in each plant these ZIP genes are so they can manipulate them to create crops with enhanced mineral content or improve the above solutions to cleaning up the ecosystem.
One Final Application
You may be hearing a lot these days about increased flooding risks around the world, largely due to deforestation and climate change. Another cause of this is agriculture which can contaminate soil and cause barren land to spread across the land (not to mention desertification as in the Saraha Desert).
By manipulating and improving the efficacy of metallophytes, barren wastelands could potentially fill up with plantlife, which in turn absorbs and holds off flooding in strategic areas around the world.
So next time you see a plant eating metal, give it a nod.
Image sources: Image source of legume tree because source links aren't working well under wrapped images | Toxic defense image | All other images CC0 Licensed
References: Genome structures and transcriptomes signify niche adaptation for the multiple-ion-tolerant extremophyte Schrenkiella parvula | An ecological approach to discover new bioactive extracts and products: the case of extremophile plants. | Phytomining | Extremophytes | New species of metal-eating plant discovered in the Philippines | Phytoremediation | Plant defense using toxic inorganic ions: Conceptual models of the defensive enhancement and joint effects hypotheses | The ZIP family of metal transporters
When I saw the plants my mind shouted "cleaning agent." So happy my guess was right. Nature always cleaning up after man or in other cases self-fixing that which was not natural. You do go deep on your research for awesome info. I like that. 👍
It feels wrong just writing about the first thing I find in a Google search so yes, a little deeper. Plus I actually learn that way =D
Good guess! Though quite a downer on humanity, messing everything up for plants to fix
Unless, of course, the first thing that pops up is quite interesting. Then you are honor bound to post it :)
I agree on learning as you research. That is the awesome, sometimes often overlooked part, of steeming.
Pretty wild stuff... Metal-eating plants...
i think i'm more interested in the phytomining process.. lemme get this straight, they plant these * metal-eating plants,* in areas where metals are abundant and then burn it just to get the metal extracted?
It seems so - burning plants can create nutritious soil in itself and there are some species of tree that actually depend on it, but it definitely sounds concerning if done on a global scale...
Thank you for clarifying
Earth will survive, just we wont. I just hope this new generation of crypto rich people will be smarter more than old rich fuck. But i doubt it. When everyone are dreaming about lambos...
Hey don't knock the lambos on steemit, you'll get yourself flagged to the ground =P
:) We should change it to Tesla
Hello @mobbs
Plant is an important food source in every habitat whether aquatic, terrestrial or arboreal; once life exist there, plant must be present and they have various mechanisms, (just like the ones you described in this content) with which they can survive in a given ecosystem.
How these plants achieve all these feats would constitute an important research topic, and I wish information in this regards would be forthcoming...
Such a wonderful content. Thanks for sharing.
Upv by
@eurogee
Unfortunately it was kinda hard to find the most recent research, a lot of the stuff coming from 2000 or 2010... Maybe I'll look harder for another post some time
This may just be the key to cleaning our rivers of toxic chemicals
I'd say there are many applications if done right
Excellent post, plants do a lot of work and they don't get to be on the spotlight!
Metals eating plants.. I hope to know where you get all these your topics that defy normal reasoning. It's lovely anyway, that's one of the specialties of your blog aside your writing skills.
thoughtful informatipn for us..thankyou for having such a great post about science. its a big learnings for steemians
hopefully the farmers are beneficial with these pots
excellente