Plants, like other organisms, are facing multiple mechanical constraints generated both in their tissues and by the surrounding environments. They need to sense and adapt to these forces throughout their lifetimes. To do so, different mechanisms devoted to force transduction have emerged. Here we focus on fascinating proteins: the mechanosensitive (MS) channels. Mechanosensing in plants has been described for centuries but the molecular identification of MS channels occurred only recently
All organisms, from bacteria to mammals and plants, experience mechanical forces. These forces are ubiquitous and very diverse coming from both the internal and the external environment. One of the most common external sources of stimulation sensed by both plants and animals is touch (pressure, shear stress). Like animals, plants are sensitive to gravity which guides their growth with respect to the gravity vector. Cells also generate their own intracellular forces as is obvious during cell division, cell elongation, or adjustment after osmotic challenge. While animals have to deal with circulating liquids (blood and urinary) and gases (lungs) as well as contractile elements (muscles), plant cells with their high turgor pressure represent very peculiar and interesting living systems from a mechanical point of view.
Over the last few years, it has become apparent that the ability of cells to sense and adapt to these forces is crucial for a wide range of biological processes. After two decades, during which the vast majority of studies were devoted to the dissection of gene regulatory pathways, mechanics is now being progressively integrated into the network, both as output (the impact of genes on cell mechanics) and input (the impact of mechanical signals on gene activity.
According to Oxford;
The sedentary lifestyle of plants can give the false impression that they are passive participants in interactions with other organisms and the broader environment. In fact, plants have evolved sophisticated perceptual abilities that allow them to monitor and respond to a wide range of changing biotic and abiotic conditions.
Such interactions include the detection and capture of animal prey by carnivorous plants, active plant responses to pollinator visitation, the perception of various cues associated with the immediate presence and feeding of herbivores, and plant responses to (olfactory) cues indicating the threat of future herbivory. We are only beginning to understand the full range of sensory cues that mediate such interactions and to elucidate the mechanisms by which plants perceive, interpret, and respond to them. Nevertheless, it is clear that plants continually gather information about their environments via a range of sensory modalities and actively respond in ways that profoundly influence their interactions with other organisms.
As per Harvard;
It is well known that as plants grow, their stems and shoots respond to outside signals like light and gravity. But if plants all have similar stimuli, why are there so many different stem shapes? Why does a weeping willow grow downwards while nearby poison ivy shoots upwards?
Using simple mathematical ideas, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) constructed a framework that explains and quantifies the different shapes of plant stems.
“We have combined, in one theory, a plant’s ability to sense itself and its environment while being constrained by gravity and its elastic nature,” said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics. “By accounting for these factors, we can explain the range of shapes seen in nature without the need for complex growth strategies. This, in turn, implies that the diversity of morphologies seen in your garden may follow from very simple causes.”
When these pathways are triggered by stimuli, one part of the shoot may grow relative to another and change shape. The shoots of the weeping willow, for example, try to grow upwards, away from gravity and towards light. But, because they are so soft, the shoots sag under the weight of gravity and cascade towards the ground. On the other hand, poison ivy shoots start by growing downwards before turning upwards.
How organisms sense and respond to these outside signals is important to understanding everything from plant growth to human development.
“Different organs in our body grow and take on their characteristic shapes by responding to both internal and external signals, such as gravity,” said Mahadevan. “We do not yet understand how large-scale shape changes arise from a combination of sensing and growth, and our study attempts to look at one example of this.”
The research was supported in part by the MacArthur Foundation.
The research is published in the Journal of the Royal Society Interface.
Credit : Harvard University
National Library Of Medicine