Abscisic acid

Definition

Abscisic acid (ABA) is a plant hormone that plays a crucial role in regulating various physiological processes, particularly during stress responses. It helps plants manage drought conditions, seed dormancy, and influences growth by acting as a signaling molecule that coordinates developmental processes.

5 Must Know Facts For Your Next Test

1. Abscisic acid is produced in response to environmental stresses such as drought and salinity, signaling the plant to activate protective mechanisms.
2. This hormone plays a key role in stomatal regulation by promoting the closure of stomata to reduce transpiration and conserve water.
3. During seed development, abscisic acid promotes seed dormancy, preventing premature germination until conditions are favorable for growth.
4. Abscisic acid is also involved in the regulation of gene expression related to stress responses, activating genes that help protect plant cells from damage.
5. In addition to drought stress, abscisic acid helps plants cope with temperature extremes by regulating growth and development under heat and cold stress.

Review Questions

• How does abscisic acid contribute to a plant's ability to respond to drought stress?
  • Abscisic acid plays a vital role in helping plants cope with drought stress by inducing stomatal closure, which reduces water loss through transpiration. When soil moisture levels decline, ABA is synthesized and transported throughout the plant, triggering this response. Additionally, ABA promotes the expression of stress-responsive genes that enable the plant to conserve resources and maintain cellular function under challenging conditions.
• Discuss the role of abscisic acid in seed dormancy and its significance for seed germination.
  • Abscisic acid is essential for maintaining seed dormancy, which ensures that seeds do not germinate under unfavorable environmental conditions. This hormone inhibits the expression of genes required for germination, effectively keeping seeds in a state of rest until conditions such as moisture and temperature become optimal. By regulating seed dormancy, ABA plays a crucial role in ensuring the survival of plant species across varying environments.
• Evaluate the impact of abscisic acid on plant growth and development during extreme temperature stress.
  • Abscisic acid impacts plant growth and development significantly during extreme temperature stress by modulating various physiological responses. Under heat stress, ABA can help regulate metabolic processes to prevent overheating and protect cells from damage. Conversely, during cold stress, ABA assists in promoting protective mechanisms such as the accumulation of antifreeze proteins. This hormone's ability to coordinate these responses underscores its importance in maintaining plant viability and adaptability in changing climates.

Related terms

Drought Tolerance: The ability of a plant to survive and thrive under conditions of limited water availability, often enhanced by the action of hormones like abscisic acid.

Stomatal Closure: The process by which plants close their stomata to reduce water loss, primarily regulated by abscisic acid during drought stress.

Seed Dormancy: A period in which seeds remain inactive or un-germinated, often regulated by abscisic acid to ensure survival until favorable conditions arise.