Table of Contents
Gibberellin signaling pathway is regulated by the Ubiquitin 26S proteolysis system. The signaling pathway is discussed in this section. It is important for any kinds of Life Science related competitive exams.
Receptor:
GID1 (GA insensitive dwarf 1)- intracellular/soluble.
Ligand:
Gibberellin
Inhibitor:
DELLA proteins are a class of nuclear proteins act as transcriptional repressor of gibberellin signaling pathway.
These proteins have a conserved DELLA (Asp-Glu-Leu-Leu-Ala) sequence at their N-terminal end that is critical for their function.
Transcription factor:
MYB proteins (GA-MYB)
Signaling pathway:
Ubiquitin 26S proteolysis system
The description of Gibberellin signaling pathway:
Like auxin, gibberellin binds to an intracellular receptor protein. It binds with the soluble gibberellin receptor termed GA insensitive dwarf1 (GID1). Gibberellin binds to GID1 triggers it’s interection with the DELLA proteins. Gibberellin receptor GID1 does not itself function as an F-box protein. This interaction stimulates binding of the DELLA proteins to SCF (Skp1/Cullin/ F-box), a ubiqitin ligase, resulting in polyuniquitination and degradation of DELLA protein by the 26s proteosome. While this relatively simple GA signalling cascade involves two major players. One is a receptor GID1 and the another one is the inhibitor DELLA protein.
The schematic representation of the Gibberellin signaling pathway:
Role of GA-MYB:
In barley, rice and Arabidopsis, a subset of MYBs have been implicated in GA signaling. GA-MYB is a positive regulator of α-amylase.
Results:
Gibberellin regulates different developmental processes throughout the life cycle of the plant, from seed germination through leaf expansion, stem elongation, flower induction and seed development.
Mutation cases:
| Mutation | Results |
|---|---|
| The aleurone layer of rice GID1 mutants with a defective gibberellin receptor | α-amylase is not synthesized. |
| Mutation in F-box protein or SCF complex | No degradation of DELLA protein |
Other related notes:
- Auxin biosynthesis: https://thebiologyislove.com/auxin-biosynthesis-pathway-2-types/
- Auxin signaling pathway: https://thebiologyislove.com/auxin-signaling-pathway/
- Cytokinin signaling pathway: https://thebiologyislove.com/cytokinin-signaling-pathway/
- Ethylene signaling pathway: https://thebiologyislove.com/ethylene-signaling-pathway/
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