From Ear Development to Density Adaptation: Molecular Regulatory Networks and Genetic Improvement of Ear Traits in Maize

Maize, a crucial global food and feed crop, requires continuous yield improvement to ensure food security. High-density planting has become a core strategy for maize yield improvement. While modifying plant architecture to enhance density tolerance in maize has been well reviewed, the regulatory mechanisms of ear development under high-density conditions remain far less clear. Therefore, this review aims to deepen the understanding of the mechanisms regulating ear traits, providing key insights into how ear architecture adapts to high-density planting. It presents the ideal ear architecture for high-density planting and offers a comprehensive overview of current morphological, genetic, and molecular insights into ear development. Furthermore, this review systematically analyzes the functions, breeding implications, and high-density regulatory roles of key ear-trait regulators and associated physiological determinants. Finally, prospective research directions are outlined, focusing on regulatory networks, multi-omics integration, ideotype design, and precision breeding to guide the coordinated improvement of density tolerance. This review not only advances the mechanistic understanding of maize ear morphogenesis but also provides a theoretical framework for breeding elite maize adapted to a high-density cultivation system.