The key difference between abscisic acid and gibberellins is that abscisic acid is an isoprenoid plant hormone whereas gibberellin is a diterpenoid plant hormone.
Plant hormones are signalling molecules in plants that can control plant growth and development. However, these molecules occur in extremely low concentrations. Abscisic acid and gibberellin are two different types of plant hormones.
CONTENTS
1. Overview and Key Difference
2. What is Abscisic Acid
3. What are Gibberellins
4. Side by Side Comparison – Abscisic Acid vs Gibberellins in Tabular Form
5. Summary
What is Abscisic Acid?
Abscisic acid is an important plant hormone that regulates the seed and bud dormancy and controls the organ size and stomatal closure. Moreover, this hormone is important in responding to environmental stress, e.g. drought, salinity, cold tolerance, freezing tolerance, heat stress, heavy metal ion tolerance, etc. We can denote this compound as ABA.
Figure 01: Chemical Structure of Abscisic Acid
Abscisic acid is an organic compound having the chemical formula C15H20O4. The molar mass of this compound is 264.32 g/mol. When extracted from plants, this compound appears as colourless crystals with a density that is slightly higher than the density of water.
In classification, we can classify abscisic acid as an isoprenoid molecule. In its most common bio-synthesis pathway, abscisic acid is formed from xanthoxin, in the presence of xanthoxin dehydrogenase enzyme. Furthermore, this plant hormone can be inactivated by glucose conjugation reaction. We can list down the effects of this hormone on plants.
- Stomatal closure
- Decreases transpiration to prevent water loss
- Inhibits fruit ripening
- Delays the cell division
- Regulates the seed dormancy
- Inhibits the synthesis of kinetin nucleotide
- Downregulates enzymes required for photosynthesis
What are Gibberellins?
Gibberellins are plant hormones that can regulate the development of plants, including stem elongation process, germination process, flowering, dormancy, etc. We can denote this compound as GA. In its classification, we can classify gibberellins as diterpenoid acids. This is because these plant hormones form from the terpenoid pathway that takes place in plastids and are modified in endoplasmic reticulum and cytosol.
Figure 02: Chemical Structure of Gibberellic Acid, a Form of 19-Carbon Gibberellin
When considering the chemical structure of gibberellins, they are tetracyclic diterpene acids. There are two major classes of gibberellins depending on the number of carbon atoms present in the molecules. They are the 19-carbon gibberellins and 20-carbon gibberellins. In general, the 19-carbon gibberellins are the biologically active form. A common example for this group of gibberellins is gibberellic acid. The effect of these plant hormones on plant growth and development include the followings:
- Breaking dormancy and other aspects of germination
- Signalling starch hydrolysis in seeds
- Tolerating cold temperatures
- Stimulating cell elongation, breaking, and budding
What is the Difference Between Abscisic Acid and Gibberellins?
Plant hormones are responsible for the regulation of plant growth and development. Abscisic acid is an important plant hormone that helps in many developmental processes, including control of organ size and stomatal closure, and seed and bud dormancy. Gibberellins are plant hormones that can regulate the development of plants, including stem elongation process, germination process, flowering, dormancy, etc. The key difference between abscisic acid and gibberellins is that abscisic acid is an isoprenoid plant hormone whereas gibberellin is a diterpenoid plant hormone.
Below infographic provides further details of the difference between abscisic acid and gibberellins.
Summary – Abscisic Acid vs Gibberellins
Plant hormones are responsible for the regulation of plant growth and development. Abscisic acid and gibberellin are two different types of plant hormones. The key difference between abscisic acid and gibberellins is that abscisic acid is an isoprenoid plant hormone whereas gibberellin is a diterpenoid plant hormone.
Reference:
1. “Abscisic Acid in Plants .” com, Study.com, Available here.
2. “Abscisic Acid.” Wikipedia, Wikimedia Foundation, 10 Feb. 2020, Available here.
Image Courtesy:
1. “Abscisic acid” By Charlesy (talk · contribs) – Own work (Public Domain) via Commons Wikimedia
2. “Gibberellic acid” By created by Minutemen using BKchem 0.12 – Own work (Public Domain) via Commons Wikimedia
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