vendredi 13 novembre 2015

58- The spirit of plants -3- Mathematics calculation


In her blog (in Spanish, with some articles translated into English), Elodie Brans published last year, an article that fits perfectly with my series "The spirit of plants."
You will find a direct access to this blog in the left column.
She gave me her permission to use it. After several failed attempts to write a personal article on the same subject, that is as concise and clear, I decided to publish it as is in Spanish and translated for French and English.
It's a bit of a lack of courage, but ultimately, if it is to say the same thing, but worse ...

So for this article "Plants, these experts in mathematical calculation"
Elodie Brans resumed a publication (in English) of the journal eLIFE

Picture from the original post of Elodie Brans

"Latest researches in plant biology make me look geraniums from my balcony with certain admiration. We tend to think that plants are inert beings, extremely fragile, valued only for what they produce (seeds, flowers, fruits, roots, tubers, wood, oxygen ...). But you can erase this image of a sort of passive sub species since we now know that, like animals, and although we can't hear them, plants "talk" between them, using various sensory mechanisms to communicate, especially in the purpose of defense.

Plants can feel, plants can express themselves ... plus now they can count!

Botanists of the British research center John Innes Centre have published this exciting work in the journal eLIFE after finding that plants are able to manage their starch reserves throughout the night so that they run out only at the just moment from dawn, to avoid a certain death by starvation.

Picture from the original post of Elodie Brans

As we all know, during the day, plants perform the photosynthesis process, essential for their growth as it is during the day that, thanks to atmospheric CO2 and energy that gives it light, plants synthesize the organic matter essential to its constitution. Overnight, in the absence of light and photosynthesis, the molecular machinery does not stop, plants continue to generate organic material, and they do so by extracting from their reserves of carbohydrates (typically of the starch) to continue to provide energy for their metabolism.

A variable and intelligent adaptation of resources?
We start from the premise that the sunset does not always occur at the same time, either because of the change of season, geographical area, or even just because unfortunately for plants in our living room, we don't always open the shutters at the same time. So if the nights do not always have the same duration, how can plants effectively manage their stock of starch without fainting before the arrival of the next morning?

To answer this question, botanists, study authors, realized a very simple experiment, but whose results are pioneering for plant organisms. They set Arabidopsis thaliana, the favorite herbaceous plant for laboratories, in different controlled light rooms, for submission to the nights of variable length. To their surprise, they observed that regardless of the length of the night, if the arrival of the night was artificially advanced or delayed, plants always consume 95% of their starch reserves accumulated during the day.

Arabidopsis thaliana from

Two hypotheses were advanced thus: either the plant adapts to the length of the night with a variable starch consumption, speeding up and slowing down to save energy until sunrise, or the plant estimates since sunset the length of the night, that is to say, it controls the consumption rate of starch to be constant every hour throughout the night.

A perfect knowledge of mathematical calculation.
To observe how plants adapt, the scientists made use of plants controlled with a preset rate of 12 hours of light / 12 hours of night, which they suddenly changed the duration of the night, reducing it to 8 hours, or increasing it to 16 hours. At each change, the plant adapted itself, and consumed again 95% of its reserves ... each time! In other words, plants "foresee" the duration of the night and their internal clock "knows" that the cycle from the dawn to the end of the night is 24 hours.
And then what will happen if the night is longer?
- If the sunset suddenly occurs at the end of 8 hours (instead of the usual 12 hours), the "biological clock" of the plant calculates 24 hours (total time) less 8 hours (day), which gives 16 hours of night.
- The plant therefore divides its reserve ratios by the number of night hours.
Conclusion: plants know to subtract and divide.

That sounds crazy, but scientists at the John Innes Centre are convinced that plants control their rate of starch consumption during the night by performing very subtle mathematical calculations, specifically arithmetical divisions !!

Can we speak of "memory" or of "intelligence"?
Other experiments were conducted, including the insertion of a short period of sunshine during the night to trick plants and restore their internal clock to zero. Maybe can you guess the outcome ... To go further in the subtlety of how these beings we thought "inferior", in fact the plant (which had reconstructed a portion of its reserves during this short period of time) didn't fall into the trap! When night came, it calculated how much darkness it remains to complete the full cycle of night and at what pace, more intense than it had initially calculated, it had to consume his partially restored stock! They would therefore have, in addition to an internal calculator, a memory.

If scientists don't yet know exactly how plants assess the duration of the night, they give for granted that it's a question of chemical interactions between two different molecules: the first one would inform on the time remaining until sunrise, and the second one notify the remaining amount of stock in the cells. Mathematical models have already confirmed this ingenious operation in which the plant sets the rate at which it will consume carbohydrate reserves during the period in which it will not have access to other sources of energy.
Picture from the original post of Elodie Brans

This discovery made me look the plant world from another perspective. Every night the plant starts a process to maximize its carbohydrate reserves, without going into the red (hence the 5% margin of safety), a process undoubtedly worthy to be compared with those of "superior" beings. It is evident that these mechanisms are essential for sustaining growth and productivity of the plant. And now many experts are wondering if we can understand how plants manage to maintain growth overnight, if we could use this discovery to improve dramatically crops.
A fascinating idea, right? "

The plant world is fascinating, and continues to surprise us by revealing totally unsuspected capacities.
This understanding should make us consider the plants in another way, but also offers prospects quite innovative in agriculture.
Indeed, it is a major pathway for optimizing agricultural production, cover the food security needs of the planet, without increasing the energetic, hydric and environmental impact of agriculture.

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