Thigmotropism
Thigmotropism (pronounced: thig-mo-TRO-pizm) is a biological phenomenon observed in certain organisms, particularly plants, where they respond to mechanical stimuli, such as touch or contact, by growing towards or away from it. The term is derived from the Greek words "thigma," meaning "touch," and "tropism," meaning "turning."
Etymology
The term "thigmotropism" is derived from two Greek words: "thigma" (θίγμα) meaning "touch" and "tropos" (τρόπος) meaning "turn." It was first used in the late 19th century to describe the behavior of plant roots growing in response to touch.
Mechanism
The mechanism of thigmotropism involves the perception of mechanical stimuli by mechanoreceptors in the organism. In plants, these mechanoreceptors are typically cells located in the root cap. Upon contact with a solid object, these cells trigger a signal transduction pathway that leads to differential growth, causing the plant to grow towards or away from the stimulus.
Examples
One of the most well-known examples of thigmotropism is the behavior of plant roots. Roots exhibit positive thigmotropism when they grow towards a touch stimulus, such as when they navigate through the soil towards sources of water and nutrients. Some climbing plants, like ivy and vines, also show positive thigmotropism when their tendrils coil around a support upon contact.
Related Terms
- Tropism: A general term for movement or growth in response to a stimulus.
- Phototropism: Growth or movement in response to light.
- Gravitropism: Growth or movement in response to gravity.
- Hydrotropism: Growth or movement in response to water.
- Chemotropism: Growth or movement in response to chemical stimuli.
See Also
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