response to gravity

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a gravitational stimulus. [GOC:hb]

Response to gravity, also known as gravitropism, is a fundamental biological process that enables plants, fungi, and some animals to orient themselves in relation to the Earth's gravitational field. This process plays a crucial role in the growth and development of organisms, ensuring optimal access to light, water, and nutrients.

The perception of gravity is primarily mediated by specialized cells known as statocytes, which are found in roots, shoots, and other parts of plants. Statocytes contain starch granules, known as statoliths, which sediment to the lowermost side of the cell in response to gravity.

The sedimentation of statoliths triggers a cascade of biochemical events that ultimately lead to differential growth. In roots, this results in a downward growth pattern, while in shoots, it promotes upward growth.

The molecular mechanisms underlying gravitropism are complex and involve a variety of signaling pathways. One key pathway involves the auxin hormone, which plays a crucial role in regulating cell growth and development.

When a plant is tilted, the statoliths in the statocytes shift, triggering a redistribution of auxin. This redistribution leads to differential growth on opposite sides of the plant organ, causing it to bend back towards the vertical position.

In addition to auxin, other signaling molecules, such as calcium ions and reactive oxygen species, have been implicated in gravitropism.

The response to gravity is essential for plants to maintain an upright posture, reach sunlight, and access water and nutrients from the soil. It is a remarkable example of how organisms have evolved to adapt to and thrive in their environment.'
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Proteins (1)

Compounds (2)