2023-11-27 05:00:03
Unlike animals, plants have cells that are all surrounded by a rigid wall. It protects them but locks them in a rigid skeleton. So how can they grow despite this wall?
Scientists from INRAE ​​and CNRS, in collaboration with Swiss and Belgian teams, have unlocked part of this secret. True architects, plants combine sugars and proteins to give the wall its strength and extensibility and enable cell growth. Beyond the contribution of knowledge, these results published on November 10 in Science, are of crucial importance for modeling and predicting the effects of environmental changes on plant growth.
The secret of plant growth finally revealed.
© INRAE ​​- Nicolas Bertrand
Plants have the ability to use solar energy to convert atmospheric CO2 into sugars. These sugars constitute an almost inexhaustible source of energy (In the common sense, energy designates everything that allows us to carry out work, make food, etc.) and serve (Servent is the contraction of the word server and client.) also building bricks. With these bricks, the plants build a rampart around each cell: the wall.
This wall serves both as a protective barrier and as support for a pressurized skeleton. The latter gives rigidity to the organs of the plant, like an inflatable mattress. Indeed, the wall is so robust that it can withstand considerable pressures inside the cell, reaching up to 10 times that of our atmosphere (The word atmosphere can have several meanings :). Curiously, the presence of this wall does not prevent the enlargement of the cells when the plant grows.
A question then arises: how can this wall grow, without losing its integrity, which would cause the cell to explode? To understand this mechanism, scientists analyzed in detail the assembly process of this wall.
To do this, they studied the growth of the pollen tube of the lady’s cress, a model plant. Its cell wall includes two major components, including fibers and a matrix, mainly made up of pectins. Pectins are well known for their role as a gelling agent in the making of jams!
An INRAE ​​team had already discovered that once deposited in the wall, pectins swell, following a chemical transformation, and allow the expansion of the wall.
Here the same team shows that these swollen pectins, covered with negative charges, behave like small magnets. And magnets attract each other, negative with positive. Here, the positive charge that binds to these pectins are wall proteins. A network is thus created, as if magnetized, which gives its resistance and extensibility to the wall.
For plants in which this protein is altered, the network does not form and during growth, the pollen tube explodes under pressure (Pressure is a fundamental physical notion. It can be seen as a reported force…) cells.
3D image of a molecularly labeled Arabidopsis thaliana pollen tube. The green signal shows the web-like structure formed by pectin polysaccharides (Pectines (from ancient Greek πηκτός / pêktós,…) in connection with the protein complexes of the cell wall. This arrangement (The notion of arrangement is used in probabilities, and in particular for…) physics (Physics (from the Greek φυσις, nature) is etymologically the…) regulated by proteins provides a support system allowing sustained growth of plant cells.
These results are fundamental for better understanding plant growth mechanisms. They are also of great importance for modeling and predicting the effects of environmental changes on the growth of cultivated plants.
Future results
Thanks to these results, researchers are currently developing numerical models making it possible to simulate and predict the growth and morphogenesis of plants according to changes in the environment (The environment is everything that surrounds us. It is the whole natural elements and…), for example those associated with climate change. In these models, it is absolutely necessary to include an explicit mechanism of cell growth.
Reference
Moussu S. et al. (2023). Plant cell wall patterning and expansion mediated by protein-peptide-polysaccharide interaction.
Science 382,719-725(2023).
DOI:
1701077313
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