QUESTION: Which of the following is not a plant hormone?
A Auxin
B Ascorbic acid
C Cytokinin
D Abscisic acid
ANSWER:
Ascorbic acid
| Hormone |
Chemical Formula |
Origin |
Function |
| Auxins |
C₁₉H₂₂O₆ |
· Apical meristem
· Young leaves |
· Promotes cell elongation
· Controls root and shoot growth
· Influences tropisms (phototropism, gravitropism) |
| Cytokinins |
Various |
· Root tips
· Developing fruits |
· Promotes cell division and differentiation
· Delays the process of aging
· Influences apical dominance |
| Gibberellins |
C₁₉H₂₂O₆ |
· Young leaves
· Stems
· Roots |
· Stimulates stem elongation
· Seed germination
· Fruit growth
· Breaks seed dormancy |
| Abscisic Acid |
C₁₅H₂₀O₄ |
· Leaves
· Stems
· Roots |
· Induces dormancy and stress responses
· Inhibits growth
· Regulates stomatal closure |
| Ethylene |
C₂H₄ |
· Various tissues |
· Promotes fruit ripening and abscission
· Inhibits stem elongation
· Influences senescence |
| Brassinosteroids |
Various |
· Pollen
· Young leaves
· Stems |
· Promote cell elongation and division
· Enhance stress tolerance
· Promote vascular differentiation |
| Jasmonates |
C₁₂H₁₁NO₂ |
· Wounded tissues
· Leaves |
· Mediate defense responses against herbivores and pathogens
· Regulate root growth |
| Salicylic Acid |
C₇H₆O₃ |
· Various tissues |
· Induces systemic acquired resistance against pathogens
· Regulates plant defense |
| Strigolactones |
Various |
· Roots
· Root exudates |
· Suppress lateral bud growth
· Promote mycorrhizal associations
· Inhibit shoot branching |
| Polyamines |
Various |
· Various tissues |
· Involved in cell growth and differentiation
· Influence stress responses and flowering |
