DBB2 regulates plant height and shade avoidance responses in maize

Area of Science:

• Plant Biology
• Genetics
• Agricultural Science

Background:

• High-density planting increases maize yield but reduces light, triggering shade avoidance responses (SAR) that limit growth.
• Understanding SAR regulators is crucial for optimizing maize architecture for dense cultivation.

Purpose of the Study:

• Identify key regulators of plant height and SAR in maize under dense planting.
• Elucidate the molecular mechanisms by which these regulators function.
• Explore their potential for improving maize varieties for high-density conditions.

Main Methods:

• Genetic analysis of double B-box containing protein DBB2 (ZmBBX) in maize.
• Investigated protein-protein interactions between DBB2, HY5, and PIF4.
• Assessed the impact of DBB2 disruption on plant height, cell elongation, and SAR.
• Analyzed gene expression of ZmGA2ox4 and ZmEXPA1.

Main Results:

• Disruption of ZmDBB2 reduced plant height and shade sensitivity, with effects partially reversed by gibberellins (GA).
• DBB2 interacts with HY5 to inhibit ZmGA2ox4, positively regulating plant height via the GA pathway.
• PIF4 induces ZmDBB2, which then forms a feedback loop with PIF4 to promote cell elongation genes like ZmEXPA1 under shade.

Conclusions:

• ZmDBB2 is a critical regulator of maize plant height and SAR, mediating shade responses through interactions with HY5 and PIF4.
• BBX proteins are key targets for genetic improvement of maize architecture for high-density planting.
• Findings offer insights into SAR mechanisms and strategies for enhancing maize grain yield.