Plants are able to remember information and react to it, thanks to an internal communications system that can be likened to a central nervous system in animals, according to a new study by a Polish plant biologist.
Plants "remember" information about light, and a certain type of cell transmits that information, much like nerves do in animals.
In the study, which was published in the early online version of the journal Plant Cell July 16, the researchers found that light shone on one leaf of an Arabidopsis thaliana plant caused the whole plant to respond. The response lasted even after the light source was taken away, suggesting the plant remembered the light input.
"The signaling continiues after the light is off; it is building short-term memory," said the lead author, Stanislaw Karpinski, in an e-mail message. "The leaves are able to physiologically 'memorize' different excess light episodes and use this stored information, for example, for improving their acclimation and immune defenses."
The leaves remember light quality as well as quantity, Karpinski added -- different wavelengths of light produce a different response, suggesting the plants use the information to generate protective chemical reactions like pathogen defense or food production.
As reported by the BBC July 14, scientists found that light shining on a leaf cell triggered a cascade of events that was immediately signaled to the rest of the plant via a type of cell called a bundle sheath cell. Those cells exist in every part of a plant. Karpinski, of the Warsaw University of Life Sciences in Poland, measured the electrical signals from those cells, and compared it to finding a central nervous system for plants.
Terence Murphy, a plant biology professor at the University of California-Davis who was not involved in the research, said shining light on that first leaf could have any number of effects.
"The leaf would be loaded up with starch, maybe; that's going to have a real effect on how it communicates through the phloem (vascular system) to other leaves. It's not unreasonable that you could illuminate one leaf and affect the other leaves," he said.
The trick is finding out how the other leaves are informed -- and that's what appears to have been done in the Polish study. Bundle sheath cells surround the veins in leaves, stems and roots, so it's reasonable to think they transmit the electrical impulse, Murphy said.
Biologists have long known that plants can remember -- they need to know whether they've gone through a cold season before they can germinate in the spring, for instance. It's not memory as we know it, but a prolonged change in plant internal systems that causes effects later.
What's more, scientists already know plants transmit electrical signals in response to a stimulus, just as nerves do. This is easily measured using a basic electrode setup, according to Murphy.
Karpinski said the light memory represents a new way for plants to respond to pathogens or disease -- normally, they respond by direct contact with an invader.
"This information would not be a revelation untill we find that plant leaves can remember it for several days and process this memorized information to (bolster) their defense mechanisms against seasonal diseases," he wrote.
Karpinski is well-known among plant biologists for earlier work on how plants respond to light stress. In a previous study, he also showed chemical signals can be passed throughout whole plants, allowing them to respond to and survive environmental changes. Understanding the mechanisms that cause those signals is a new step, however.
William John Lucas, distinguished professor of plant biology at UC-Davis and chair of the plant biology department, said an internal communication system would provide a wealth of information to different parts of the plant.
"A particular tissue within a plant needs to be able to signal to the rest of the plant in terms of what are its conditions, what should you expect," he said. "If a young leaf is emerging out of a plant, it would be nice for that leaf to know about the conditions in which it is going to emerge."
Lucas studies how plants pick up non-biological information, such as water and light, and how they transmit that information so the entire plant knows under which constraints it will grow. Plants can't move to a sunnier, wetter spot, so they need to make the most of their environment.
Tapping into their "nervous system" would help scientists understand how they do that, Lucas said. That knowledge could lead to optimized food crops or hardier trees.
"There are no neurons in plants, but there is a communication network that we don't fully understand," he said. "There are important implications for these kinds of studies."
I knew it!! The earth is more advanced than we can imagine. It is using us like an advanced bacteria. Earth knows if we live Earth will live.
Makes sense, trees are older than almost everything, why wouldn't they have some kind of communication system or memory?
So what will vegans eat?
LOL @ Portillo
Haven't we already established the response of plants to vibrational stimuli like sound? It would make sense that they have some sort of "memory" pattern of cell behavior and chemical response to light and radiation as well. To see proof of that illustrated is really cool. Another fascet of this research would be to see if these responses are actually stored in the cells themselves, say in the old growth rings of a tree, so the plant knows how to react to a certain environmental condition from experience. Would that count as some sort of sentience?
i've read that the genome for rice is longer then humans; LONG LIVE OUR PLANT OVERLORDS!
Piffle! That's nothing.
I used to have a rutabaga that occasionally got out of the garden and scared the bejeebers out of the neighbor kids by chasing them around.
Carrot juice is murder!
I've had the thought that plants must have a nervous system and some way to think. How in the world would a plant evolve into having thorns to cause pain and defend itself if it has no concept of pain itself. They feel pain!!!!!
@phildo. It's natural selection. The plants who have thorns survive and breed. Those who don't find their way into an animals diet, thus eventually extinct. Evolution isn't a thinking matter.
@a posteriori. Your right, evolution is not a thinking matter. You have to turn off your brain to belive in it.
Evolution is not a thinking mater (process), but due to evolution thinking alive matter is made. Science-Fiction world of "Avatar" is becoming the reality (the scientific reality). PLANTS REMEMBER (Soul tree) and THINK!!! James Cameron is great!!!
"Your right, evolution is not a thinking matter. You have to turn off your brain to belive (sic) in it."
Yeah. Crazy, isn't it? IT is so much more rational to believe in a vengeful bearded old man in the sky that loves us all so much at first that he takes several opportunities to destroy us then sends his kid to die for us. Brilliant.
And never mind that this same jolly, loving fellow allows earthquakes, wars, famine, hurricanes ...
Yes. I can see how much more rational that is!
in about a month from now we will see a large group of people dying because they will refuse to eat anything. this group of people are know as philisophical vegetarians. now that plants can remember just like animals and have similar communication systems it will be morally wrong to eat plants as well. to those vegetarians be human and live, stay hypocrites or starve your choice..
p.s. I don't support animal cruelty and this is meant as a joke thank you
Wow, everyone's getting excited.
@Portillo: Well, you'll notice the article often puts the term "nervous system" in quotation marks and does the same to the word "remember" early on. It also says "it's not memory as we know it, but a prolonged change in plant internal systems that causes effects later" and "there are no neurons in plants, but there is a communication network that we don't fully understand". I'm pretty sure the title of the article is metaphorical. Plants' ability to change when exposed to ("react to") external stimuli and the fact that the way they respond to diseases is different for the next few days after they've been exposed to certain stimuli (what the article means when it says they "remember" information) doesn't mean they're sentient.
Hmmm... it would be interesting to test carnivorous plants; venus flytrap, sundews, etc.
Imagination is the key to Invention
Plants are to Trees as Dogs are to Humans.
Plants may have memory, but Trees talk to each other continuously. Imagine if we could understand what
they have to say, Imagine all they have tried to
tell us, Imagine, LOL, that if a tree falls in the forest,
and no one is around to hear it, -Does it make a sound? Yes, the substance of a apparent philosophical riddle,
is actually natures greatest joke, on you.
Unfortunately, the trees haven't been laughing in quite a while.
Not only do they think, but now, after I conducted my own reaserch, I have found that certin varities of flowers respond to both Journey and Rush music!
well, there goes my plans for making technology out of plants they might remember me trying to make a tv out of them lol but Im more for making them glow to replace street lamps.