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Plant Hormone Abscisic acid (ABA): Major Functions

Stress hormone
  • Chemically: dextro rotatory cis-sesquiterpene
  • Active form of ABA (+) cis ABA & (+)-2-trans ABA
Abscisic acid (ABA) which regulates flowering in Arabidopsis

  •  Mevalonic acid or xanthophylls like violaxanthin
                                                                            Major effects
           Stress response: water stress increases ABA production that initially induce stomatal closure and later increases water holding capacity of root tissues and promotes root growth and inhibits shoot growth.
  • Maintains seed dormancy 
  • Promotes abscission and senescence
  • Incorrectly named, not related to abscission, ethylene is the hormone that is directly involved in abscission. ABA promotes abscission.
  • Important in water stress and other stresses 
  • Causes stomatal closure
  •  Prevents premature germination of seeds
  • Changes gene expression patterns
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