Leveraging Genome Editing to Revive Multi-Ear Traits for Climate Resilient Maize: Systematic Review

Maize is central to global food security because of its high yield potential and broad adaptability. However, modern breeding has unintentionally narrowed its genetic base by favoring a single-ear ideotype, thereby reducing resilience to climate stress and limiting yield stability under adverse conditions. As climate variability intensifies, the buffering capacity of multi-ear phenotypes is becoming increasingly important. This review synthesizes evidence demonstrating that reintroducing prolificacy is both promising and challenging, as the trait is polygenic and constrained by physiological trade-offs involving source-sink balance, ear initiation, and developmental synchrony. Recent advances in genome-editing technologies, including CRISPR-Cas systems, base editing, and prime editing, now allow precise modification of key regulators of ear architecture, such as tb1, fea2, RA1/RA2, and hormonal pathways controlling axillary meristem activity and ear number. Emerging insights into synchrony-related genes, including GIF1, RA2, and gibberellin-deactivation loci, further support targeted editing strategies to coordinate ear development and minimize yield penalties. By integrating these molecular tools, breeders can design multi-ear ideotypes that enhance yield stability and climatic adaptation. To accelerate progress, future research should prioritize the systematic identification and validation of promoters and cis-regulatory elements that fine-tune prolificacy pathways, alongside the development of high-throughput phenotyping platforms capable of capturing subtle variation in ear number, developmental synchrony, and resource allocation.