Bilateral symmetry genes: If they exist, how would we know?

Area of Science:

• Developmental biology
• Genetics
• Evolutionary biology

Background:

• Symmetry is fundamental to organismal form, from cells to whole bodies in plants and animals.
• Bilateral symmetry, common in animals, involves complex genetic regulation.
• Genes controlling radial-to-bilateral symmetry transitions exist in plant flowers.

Purpose of the Study:

• To review current knowledge on the genetics of symmetry, with a focus on bilaterality.
• To identify gaps in understanding the genetic underpinnings of bilateral symmetry.
• To highlight the paradox of known symmetry-breaking genes versus unidentified symmetry-establishing genes.

Main Methods:

• Literature review of genetic studies on symmetry in animals and plants.
• Comparative analysis of gene functions across different clades.
• Synthesis of findings on symmetry-breaking and symmetry-establishing genes.

Main Results:

• Symmetry-breaking genes directing left-right asymmetry are identified in animals (e.g., heart positioning).
• Genes controlling floral symmetry transitions are characterized in specific plant groups.
• A key paradox exists: genes initiating symmetry breaking are known, but those establishing bilateral symmetry are not.

Conclusions:

• The genetic mechanisms for establishing bilateral symmetry remain largely unknown.
• Further research is needed to identify genes specifically dedicated to bilateral symmetry.
• Understanding the genetics of symmetry is crucial for developmental and evolutionary biology.