Ancient duons may underpin spatial patterning of gene expression in C₄ leaves

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• C4 photosynthesis offers significant yield potential if transferred to C3 crops.
• C4 photosynthesis evolution is thought to involve a few master regulators.
• Understanding these regulators is key to engineering improved crop photosynthesis.

Purpose of the Study:

• To identify components of master regulators controlling C4 photosynthesis.
• To investigate the role of specific DNA motifs in C4 gene expression.
• To explore the potential of these motifs for crop improvement.

Main Methods:

• Identification of cis-acting elements within the coding sequences of C4 photosynthesis genes.
• Analysis of gene expression patterns in C4 and C3 plants.
• Comparative genomics to assess the conservation of identified motifs.

Main Results:

• A pair of cis-elements, termed duons, were identified in genes expressed in C4 bundle sheath cells.
• These duons have a dual role: coding for amino acids and regulating spatial gene expression.
• Duons repress C4 photosynthesis gene transcription in mesophyll cells.
• The identified duons are conserved across land plants and some algae.

Conclusions:

• C4 photosynthesis likely co-opted an ancient regulatory code (duons) for spatial gene expression.
• These intragenic regulatory sequences offer a novel target for engineering enhanced photosynthesis in crops.
• Exploiting these duons could lead to significant yield improvements in C3 crops.