Natures wonders: Plant awareness (Introduction)

by David Turell @, Saturday, July 20, 2019, 18:47 (60 days ago) @ dhw

This article says plants have a sort of cognition and memory:

"Plants are not simply organic, passive automata. We now know that they can sense and integrate information about dozens of different environmental variables, and that they use this knowledge to guide flexible, adaptive behaviour.

"For example, plants can recognise whether nearby plants are kin or unrelated, and adjust their foraging strategies accordingly. The flower Impatiens pallida, also known as pale jewelweed, is one of several species that tends to devote a greater share of resources to growing leaves rather than roots when put with strangers – a tactic apparently geared towards competing for sunlight, an imperative that is diminished when you are growing next to your siblings. Plants also mount complex, targeted defences in response to recognising specific predators. The small, flowering Arabidopsis thaliana, also known as thale or mouse-ear cress, can detect the vibrations caused by caterpillars munching on it and so release oils and chemicals to repel the insects.

"Plants also communicate with one another and other organisms, such as parasites and microbes, using a variety of channels – including ‘mycorrhizal networks’ of fungus that link up the root systems of multiple plants, like some kind of subterranean internet. Perhaps it’s not really so surprising, then, that plants learn and use memories for prediction and decision-making.


"In the biologists’ favourite experimental plant, A thaliana, a gene called FLC produces a chemical that stops its little white blooms from opening. However, when the plant is exposed to a long winter, the by-products of other genes measure the length of time it has been cold, and close down or repress the FLC in an increasing number of cells as the cold persists. When spring comes and the days start to lengthen, the plant, primed by the cold to have low FLC, can now flower. But to be effective, the anti-FLC mechanism needs an extended chilly spell, rather than shorter periods of fluctuating temperatures.

"This involves what’s called epigenetic memory. Even after vernalised plants are returned to warm conditions, FLC is kept low via the remodelling of what are called chromatin marks. These are proteins and small chemical groups that attach to DNA within cells and influence gene activity. Chromatin remodelling can even be transmitted to subsequent generations of divided cells, such that these later produced cells ‘remember’ past winters. If the cold period has been long enough, plants with some cells that never went through a cold period can still flower in spring, because the chromatin modification continues to inhibit the action of FLC. (my bold)


"Both epigenetic and ‘brainy’ memories have one thing in common: a persistent change in the behaviour or state of a system, caused by an environmental stimulus that’s no longer present.


"Furthermore, plant behaviour frequently involves chemical and structural changes that are simply too small, too fast or too slow for us to perceive without equipment.


"Some theorists worry that concepts such as ‘plant memory’ are nothing but obfuscating metaphors. When we try to apply cognitive theory to plants in a less vague way, they say, it seems that plants are doing something quite unlike animals. Plant mechanisms are complex and fascinating, they agree, but not cognitive. There’s a concern that we’re defining memory so broadly as to be meaningless, or that things such as habituation are not, in themselves, cognitive mechanisms. (my bold)


"Of course, it’s a stretch of the imagination to try to think about what thinking might even mean for these organisms, lacking as they do the brain(mind)/body(motor) divide. However, by pushing ourselves, we might end up expanding the concepts – such as ‘memory’, ‘learning’ and ‘thought’ – that initially motivated our enquiry. Having done so, we see that in many cases, talk of plant learning and memory is not just metaphorical, but also matter-of-fact."

Comment: Metaphor or fact? Note my bolds. As the reader might suspect, I view the epigenetic aspects of this issue as indication that all of this is automatic and built into the genetic instructions in plants, as with cell responses in animals. For me it is all one pattern, since with plants we are the outside looking in as with animal cells. The reason: life was designed by a mind that could plan for the necessary responses. For the interested reader this is a huge article, and I have not included descriptions of plant responses to stimuli.

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