Definition of
geotropism
He geotropism is a kind of tropism: a shift or inclination of orientation that a sessile organism (which is fixed on the substrate) makes to respond to a stimulus. In this case, the tropism in question is produced by the force of gravity.
The gravity is a force exerted by the planet Land on all the bodies that are on its surface. The terrestrial center attracts all objects with mass, which receive the action of this force. Plants, in this framework, respond to gravity through geotropism.
- What is geotropism
- Classification according to type
- Geotropism and auxin
- The SAURs
- Related Topics Tree
What is geotropism
Also called gravitropismgeotropism is a reaction to the intensity of the gravitational field. The roots of the plants, in order to fulfill their functions, grow towards the interior of the Land, sinking into the substratum; the stems, on the other hand, develop their growth upwards, extending over the surface.
The different concentrations of auxin allow the floors develop geotropism. This plant hormone or phytohormone is responsible for regulating the growth of the plant, promoting cell development. Depending on how auxin is concentrated, the specimen grows in one way or another.
It can serve you: Cell
Classification according to type
When geotropism accompanies the force of gravitythere is talk of positive geotropism (the roots). On the other hand, if geotropism is opposite to gravity, it is a negative geotropism (the stems).
Geotropism, in short, allows plants to develop, subsist and reproduce. With negative geotropism, the stems and leaves develop in the aerial environment and can perform the photosynthesis thanks to sunlight; with positive geotropism, the roots move in the same direction as gravity to access the nutrients and water they need.
See also: Photosynthesis
Geotropism and auxin
Returning to the concept of auxinwe can say that it is a set of phytohormoneswhich are also known as hormones vegetables, and are the substances produced by plant cells. They are usually found in leaves and their action on other types of cells is equivalent to that of a chemical messenger.
The main role of auxin in the framework of the regulation of development is the elongation of plant cells. The synthesis of these hormones takes place in the stem apical meristema meristematic tissue (in other words, it is responsible for growth) that is located at the tip of the plant, particularly in the area of cell division and expansion, and gives rise to the stems, leaves, and flowers.
Precisely, at the core of the definition of geotropism is this group of plant hormones, which reaches its maximum level in the apex and decreases as you move away from it.
Continue on: Elongation
The SAURs
In the geotropism of the hypocotyls (the germinating part of the seed) of soybean, it has been verified that some messenger RNA small (the ribonucleic acid that carries the genetic code from the DNA of the cell nucleus to a ribosome located in the cytoplasm), which are known by the name SAURs. The synthesis of SAURs requires the addition of auxins for its stimulation.
The expression of SAURs in soybean sprouts growing in the vertical direction is symmetric, while for those with horizontal growth the expression is modulated so that they accumulate especially in the basal half of the hypocotyl. In this way, the response that gives rise to the curvature of the organ and the increase in verticality of the plant begins. This is just one example of geotropism that demonstrates the complexity of the processes that take place in living beings, however small they may be.
See also: Ribosomes