Abscisic acid (ABA) is a plant hormone that plays a crucial role in protecting plants against drought stress. Here are the mechanisms through which ABA helps plants cope with drought:
1. Stomatal Closure: When plants experience water scarcity, ABA helps in regulating the closure of stomata. Stomata are tiny openings on the surface of leaves that allow transpiration (loss of water vapor) and facilitate gas exchange. A high ABA level triggers the closure of stomata, reducing transpiration and preventing excessive loss of water from the leaves. This helps plants conserve water during drought conditions.
2. Root Growth Inhibition: ABA also inhibits the growth of roots. By doing so, it reduces water uptake and conserves the existing water in the soil for the survival and growth of the plant. This mechanism helps the plant maintain a balanced water status, even in the face of limited water availability.
3. Seed and Bud Dormancy: ABA induces and maintains seed dormancy, preventing premature germination in unfavorable environmental conditions such as drought. Additionally, it promotes bud dormancy, preventing early bud break and growth during dry periods. This allows plants to delay growth until more suitable conditions become available.
4. Cellular Protection: ABA helps protect plant cells from damage caused by drought stress. It can act as an antioxidant, scavenging harmful reactive oxygen species (ROS) that accumulate under drought conditions. By reducing oxidative stress and modulating various stress-related proteins, ABA helps maintain the integrity and function of plant cells.
Overall, ABA acts as a regulator that coordinates various physiological, developmental, and molecular responses in plants to cope with drought stress. By controlling stomatal closure, root growth inhibition, seed and bud dormancy, as well as providing cellular protection, ABA helps plants survive and adapt to drought conditions.
How does abscisic acid protect plants against drought?
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