Abstract:

Dense planting is a core strategy for unlocking maize yield potential and ensuring national food security in China. However, under high-density cultivation, conventional planophile maize varieties often suffer from canopy closure, reduced photosynthetic efficiency, and increased lodging risk, which have become limiting factors constraining yield gains from dense planting. Leaf angle, a key agronomic trait that governs canopy architecture, optimizes light distribution within the plant community, enhances radiation use efficiency, and improves lodging resistance, has emerged as a central target in modern molecular breeding of compact maize. Recent advances in maize functional genomics have enabled the cloning of key genes regulating leaf angle, such as ZmTAC1, ZmRAVL1, and ZmILI1, along with the progressive elucidation of their molecular regulatory mechanisms. CRISPR/Cas9-based genome editing, characterized by its precision, high efficiency, capacity for multiplex targeting, and absence of linkage drag, provides a transformative technological platform for the targeted modification of leaf angle and the rapid development of compact germplasm. This review systematically synthesizes the genetic architecture and molecular regulatory networks governing maize leaf angle, with emphasis on the functional dissection of key regulatory genes. We summarize the progress and current challenges in applying both single-gene and multiplex genome editing for the creation of compact germplasm, and discuss future directions in this field. This synthesis aims to provide a reference for the molecular design breeding of next-generation, compact maize varieties in China.

Key words: maize, molecular breeding, genome editing, compact plant architecture, leaf angle