★ Mechanoreceptors (in plants)
A mechanoreceptor is a sensory organ or cell that responds to mechanical stimulation such as touch, pressure, vibration, and sound from both the internal and external environment. Mechanoreceptors are well documented in animals and are integrated into the nervous system as sensory neurons. While plants do not have nerves or a nervous system like animals, they also contain mechanoreceptors that perform a similar function. Mechanoreceptors detect a mechanical stimulus coming from within the plant and from the environment. The ability to sense vibrations, touch, or other disturbances is an adaptive response to herbivory and attack, so that the plant can properly protect itself from harm. Mechanoreceptors can be organized at three levels: molecular, cellular, and organ.
1.1. The mechanism of sensation. Signal. (Сигнал)
There is a growing body of knowledge about how mechanoreceptors in plant cells receive information about mechanical stimulation, but there are many gaps in the current understanding. Although a complete model cannot yet be formed, we know much of what happens on the plasma membrane.
The plasma membrane is full of membrane proteins and ion channels. One of the types of ion channels is Mechanosensitive MS-ion channels. MS channels differ from other membrane proteins in that their primary Gating stimulus is force, so that THEY open channels for ions to pass through the membrane in response to mechanical stimuli. This system allows the physical force to create a flow of ions, which then leads to signal integration and response, as detailed below. It is assumed that MS channels are a working mechanism in the perception of gravity, vibration, touch, hyperosmotic and hypoosmotic stress, pathogenic invasion, and interaction with commensal microbes. MS channels have been found in many genera, as well as in various plant organs, such as leaves and stems, and are localized on various cell membranes.
Mechanoreceptors can not only be present in the plasma membrane of cells, but also exist as whole cells, the main purpose of which is to detect mechanical stimuli. A well-known example is the trigger hairs on a Venusian fly Trap. When repeatedly touched for a certain period of time, the plant slams shut, capturing and digesting its prey.
1.2. The mechanism of sensation. Integration and response. (Интеграция и реагирование)
As soon as a plant perceives a mechanical stimulus through mechanoreceptor cells or mechanoreceptor proteins in the cells plasma membrane, the resulting ion flow is integrated through signaling pathways leading to a response. The integration and response of the signal cascade depends on the type of stimulus and the specific type. For example, this can manifest as a change in turgor pressure, leading to movement, secretion of protective chemicals, and stomatal closure.
2.1. Examples. Venereal Flycatcher. (Венерическая Мухоловка)
The Dionaea muscipula Venus Flycatcher is known to quickly close its lobes when touched to capture and digest its prey. The unique carnivorous plant has extremely sensitive mechanosensory hairs located on the surface of its trap. When one hair touches its prey, the anion channels will open and depolarize the plasma membrane, thereby triggering an AP action potential through the phloem. AP leads to accumulation of Ca2 ions. If the hair is then left alone, the Ca2 will dissipate. However, if another hair is stimulated within 30 seconds of the first hair, then another AP is triggered, and it reaches a threshold that causes changes in the turgor of cells in the petiole. This will cause the trap to quickly snap shut, trapping the worshipper inside its petals.
As the victim moves around inside the trap, it bumps more and more into the mechanosensory hairs, thus causing the repeated triggering of the APS. Just three APS, including the first two, initiate the production of signal pathways of the hormone Jasmonic acid, creating a hermetic seal, starting the secretion of digestive enzymes and regulating the production of transporters for the absorption of nutrients.
2.2. Examples. Arabidopsis thaliana
When caterpillars chew leaves, they create a very specific vibration pattern. Arabidopsis thaliana plants have adapted to trigger chemical defenses when they detect these mechanical vibrations to protect themselves from the ongoing herbivore. While signal perception, integration, and response for this system have not yet been thoroughly studied, the General principles of mechanosensory stimulation are considered correct. Mechanoreception is believed to begin by triggering mechanosensors in the cell wall and / or plasma membrane of leaf cells, causing flows of Ca2, reactive oxygen species ROS, and H−ions. These fluxes initiate signaling pathways that include many plant hormones and rapid gene expression that respond early to many plant stresses. These genes regulate the production of chemical defense molecules such as glucosinolates, polyphenolic anthocyanins, and a set of volatile compounds. The plant secretes these chemicals not only in the leaves that are being attacked, but also in other leaves of the plant. It is hypothesized that while there are other signals that tell a plant that it is herbivorous, it is mechanical vibrations that cause the entire plant to respond.
Users also searched:
mechanoreceptors (in plants), dionaea. mechanoreceptors (in plants),
no need to download or install
Pino - logical board game which is based on tactics and strategy. In general this is a remix of chess, checkers and corners. The game develops imagination, concentration, teaches how to solve tasks, plan their own actions and of course to think logically. It does not matter how much pieces you have, the main thing is how they are placement!online intellectual game →