Multiple Gibberellin Receptors Contribute to Phenotypic Stability under Changing Environments

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Gibberellin (GA) signaling is crucial for plant growth and development.
• GA perception involves GIBBERELLIN-INSENSITIVE DWARF1 (GID1) receptors that target DELLA proteins for degradation.
• Tomato has one DELLA protein (PRO) and three GID1 receptors (SlGID1a, GID1b1, GID1b2).

Purpose of the Study:

• Investigate the specific roles and redundancy of tomato GID1 receptors in GA responses.
• Determine how GID1 receptor function affects plant growth and stability under varying environmental conditions.

Main Methods:

• Generated CRISPR/Cas9-derived *gid1* single, double, and triple mutants in tomato.
• Assessed GA responses, including germination and growth, under optimal and field conditions.
• Utilized yeast two-hybrid assays to determine PRO-GID1 binding affinities.

Main Results:

• The *gid1* triple mutant was severely dwarf and GA-insensitive, indicating essential roles for GID1 receptors.
• Under optimal conditions, GID1 receptors showed functional redundancy with mild phenotypes in single mutants.
• GID1a exhibited the strongest effects on germination and growth, with the highest affinity for PRO.
• Environmental stress revealed loss of redundancy, with *gid1a* mutants showing dwarfism exacerbated by loss of GID1b.

Conclusions:

• Multiple GA receptors contribute to phenotypic stability, particularly under environmental extremes.
• GID1a plays a unique role in sustained GA responses, while GID1b receptors contribute to stability.
• Understanding GID1 receptor function is key to manipulating GA signaling for crop improvement.