Difference Between Thigmomorphogenesis and Nastic Movement

The key difference between thigmomorphogenesis and nastic movement is that thigmomorphogenesis is an altered growth and development of plants shown in response to mechanical stimulation while nastic movement is a plant movement that occurs in response to environmental stimuli, independent of the direction of the stimulus.

Unlike animals, plants cannot move. However, similar to animals, plants respond to external stimuli. Plants grow towards or away from the sunlight, gravity, etc. Furthermore, plants respond to mechanical stimuli such as touch, vibration, etc. Thigmomorphogenesis is the altered growth and development patterns shown by plants as a response to mechanical stimuli. In contrast, nastic movement is a plant movement which is independent of the direction of the stimulus.

CONTENTS

1. Overview and Key Difference
2. What is Thigmomorphogenesis 
3. What is Nastic Movement
4. Similarities Between Thigmomorphogenesis and Nastic Movement
5. Side by Side Comparison – Thigmomorphogenesis vs Nastic Movement in Tabular Form
6. Summary

What is Thigmomorphogenesis?

Thigmomorphogenesis is a phenomenon that describes a plant response to mechanical stimulation such as wind and constant forces (such as gravity), etc. As a result of mechanical stimuli, plants show different growth and development patterns. Rubbing and bending of stems by strong winds, rainstorms, grazing animals, and farm machinery can inhibit the overall growth of plants and can alter their growth patterns. Therefore, they are processes of thigmomorphogenesis.

Due to mechanical stress, stems may stop their elongation, and increase their girth size instead. Therefore, decreased shoot elongation and increased radial expansion are the two most common thigmomorphogenetic responses shown by plants. Moreover, some plants inhibit their upward growth when subjected to shaking for a certain period daily. The plants growing in windswept mountains also show altered growth patterns due to wind stress.

What is Nastic Movement?

Nastic movement is a non-directional response shown by plants to an external stimulus. Most importantly, it is an immediate response of plants. Most importantly, nastic movements do not depend on the direction of the stimulus. Similar to tropism, nastic movements are also vital for plants. For example, closing of the carnivorous Venus Flytrap leaf when it captures a prey is an important nastic movement. Also, the folding of Mimosa leaves when it receives a touch is another common nastic movement.

These movements can be mainly due to the changes in turgor pressure of the plants. Epinasty, hyponasty, photonasty, nyctinasty, chemonasty, hydronasty, thermonasty, geonasty and thigmonasty are types of nastic movements.

What are the Similarities Between Thigmomorphogenesis and Nastic Movement?

• Thigmomorphogenesis and nastic movement are two types of plant responses to environmental stimuli.
• They can be growth responses.
• Plant hormones play a major role in both processes.

What is the Difference Between Thigmomorphogenesis and Nastic Movement?

Thigmomorphogensis is an altered growth and development of plants shown in response to mechanical stimulation. On the other hand, nastic movement is a plant response movement which is independent of the direction of the stimulus. So, this is the key difference between thigmomorphogenesis and nastic movement. Moreover, thigmomorphogenesis is very slow response occurring over a long time while nastic movement is a rapid response.

Below infographic summarizes the between thigmomorphogenesis and nastic movement.

Summary – Thigmomorphogenesis vs Nastic Movement

Thigmomorphogenesis is a mechanically-induced response of plants. Plants react slowly over time by altering their morphology as well as their growth rate. Therefore, it is a very slow response. Common thigmomorphogenetic responses include decreased shoot elongation and increased girth. Moreover, some plants alter their chlorophyll content, hormone levels, biotic and abiotic stress resistance, pithiness, flowering time, senescence, and stomatal aperture as thigmomorphogenetic responses. Nastic movement is another type of plant response shown to external stimuli. But unlike other movements, nastic movements are independent of the direction of the external stimulus. So, this summarizes the difference between thigmomorphogenesis and nastic movement.

Reference:

1. Chehab, et al. “Thigmomorphogenesis: a Complex Plant Response to Mechano-Stimulation.” OUP Academic, Oxford University Press, 16 Dec. 2008, Available here.
2. “Nastic Movements in Plants: 4 Types (With Diagram).” Biology Discussion, 26 Oct. 2015, Available here.

Image Courtesy:

1. “Mimosa Pudica”  By Hrushikesh – Own work (CC0) via Commons Wikimedia
2. “92841” (CC0) via Pixabay