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ROLE OF ABSCISIC ACID

  1. Abscisic acid is a stress hormone, which is also known as dormin due to the effect of bud dormancy seen in the plant during the presence of abscisic acid.
  2. It was first discovered as an inducing substance for the fall of cotton fruits.
  3. The main role of the hormone is dormancy, it effects on the induction and maintenance of dormancy.
  4. It also stimulates stomata closing during the condition of water stress.
  5. It plays a role in decreasing the resistance for the water movement across the membrane and increase the ion flux of root.
  6. The presence of this hormone inhibits the stem elongation whereas sometimes it promotes the growth of roots.
  7. ABA stimulates the concentration of calcium in the cytosol that activates anion channels by which anions release from the guard cells and the membrane gets depolarized.
  8. The change in membrane potential deactivates K+ in channel and activates K+out channel, which leads to the stomatal closing by losing the guard cell turgor.
  9. ABA also inhibit potassium uptake and proton pump, which performs the major role in the stomatal closing stimulated by blue light.
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