Maize COMPACT PLANT 3 regulates plant architecture and facilitates high-density planting

Area of Science:

• Plant Biology
• Genetics
• Agricultural Science

Background:

• Compact plant architecture is essential for efficient light capture and increased crop yield, especially in maize (Zea mays L.) under high planting densities.
• Understanding the genetic regulation of plant architecture is crucial for developing strategies to enhance crop productivity.

Purpose of the Study:

• To isolate and characterize a novel maize gene, COMPACT PLANT 3 (CT3), involved in regulating plant architecture.
• To elucidate the molecular mechanism by which CT3 influences plant height and leaf angle, and its interaction with other regulatory factors.
• To assess the potential of CT3 and its interacting partners for improving maize yield in high-density planting systems.

Main Methods:

• Map-based cloning was employed to isolate the CT3 gene.
• Genetic analysis, including studies of ct3 and DIL1 mutants, was performed to understand their regulatory roles.
• Transcriptome and DNA profiling analyses were conducted to identify shared target genes and understand TF interactions.
• Biochemical assays, including direct binding studies, were used to confirm protein interactions and regulatory functions.
• Mutant alleles were introduced into elite maize hybrids to evaluate their agronomic performance.

Main Results:

• The COMPACT PLANT 3 (CT3) gene, encoding a GRAS protein, was isolated and found to regulate maize plant architecture.
• CT3 interacts with the AP2 transcription factor DWARF AND IRREGULAR LEAF 1 (DIL1), regulating leaf angle and plant height via a shared pathway.
• CT3 acts as a co-regulator, enhancing DIL1's DNA binding affinity and transcriptional activity on target genes, including cell wall-related genes ZmEXO1 and ZmXTH14.
• Mutants in CT3, DIL1, and ZmEXO1 exhibit defective cell wall integrity and reduced cell wall components.
• Introduction of ct3 or dil1 mutant alleles into elite maize hybrids resulted in more compact architecture and increased yield under high planting density.

Conclusions:

• CT3 and DIL1 form a regulatory complex that controls maize plant architecture by modulating cell wall-related gene expression.
• This CT3-DIL1 pathway provides a novel target for genetic improvement of maize, leading to enhanced yield potential in high-density cultivation.
• The findings offer valuable insights into the genetic basis of plant architecture and present a strategy for developing higher-yielding maize varieties.