Summary
ABA triggers guard cell closure and gene responses that help plants survive water stress.
In depth
Drought raises ABA, which binds PYR/PYL receptors, inactivates PP2C phosphatases and activates SnRK2 kinases, causing guard cells to lose K+ and water so stomata close. ABA also induces protective genes.
ABA accumulates in roots and leaves under water deficit; it reduces water loss and induces tolerance genes. ABA also maintains seed dormancy and delays germination until conditions improve.
Common mistake: ABA does not 'cause' leaf fall by itself; that involves ethylene and auxin balance.
ABA is made from carotenoids in roots and leaves and moves to guard cells. Its rise within minutes of water deficit closes stomata, which reduces water loss, and long term it induces genes for dehydration tolerance (LEA proteins, osmolytes). ABA also maintains seed dormancy and drives seed maturation and desiccation tolerance. Mutants such as the wilty tomato (flacca) cannot make ABA and wilt.
Drought tolerance can be improved by breeding or engineering ABA signalling, deep roots and osmotic adjustment, and farmers use deficit irrigation. Resurrection plants (Craterostigma) survive near total dehydration and revive when rewatered. Understanding ABA is vital under climate change.
Example: in a drought, the closing of stomata lowers photosynthesis too, showing the trade-off.
Frequently asked questions
What is Abscisic Acid and Drought?
ABA triggers guard cell closure and gene responses that help plants survive water stress.
Which area of biology covers Abscisic Acid and Drought, and how advanced is it?
Abscisic Acid and Drought is one of the 56 topics in Plant Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Stomata, CAM Photosynthesis, Apical Dominance.
Can you give an example of Abscisic Acid and Drought?
Drought-tolerant crops are engineered by altering ABA signalling.
What should I learn before Abscisic Acid and Drought?
Work through the Beginner topics in Plant Biology first, such as Plant Kingdom, Photosynthesis, Chlorophyll, then return to Abscisic Acid and Drought. Advanced topics assume the Intermediate vocabulary.
What topics are related to Abscisic Acid and Drought?
The closest topics to Abscisic Acid and Drought are Stomata, CAM Photosynthesis, Apical Dominance, Plant Water Potential. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Abscisic Acid and Drought?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Abscisic Acid and Drought. To practise the whole of Plant Biology, use the Plant Biology quiz.
How is Abscisic Acid and Drought different from Stomata?
Abscisic Acid and Drought: ABA triggers guard cell closure and gene responses that help plants survive water stress. Stomata: Pores on leaves flanked by guard cells that open and close to regulate gas exchange and water loss. Read both side by side and note what each one explains.
What is a common mistake about Abscisic Acid and Drought?
ABA does not 'cause' leaf fall by itself; that involves ethylene and auxin balance.
How should I study Abscisic Acid and Drought step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Stomata and explain the difference aloud. Finally, take the Plant Biology quiz and come back to this page for any question you miss.