Maize Improvement Based on Modern Breeding Strategies: Progress and Perspective

As a primary food cereal, maize (Zea mays L.) has been domesticated for thousands of years and undergoes four breeding stages to date, including Breeding 1.0 (experience breeding), Breeding 2.0 (experimental breeding), Breeding 3.0 (biological breeding), and Breeding 4.0 (intelligent breeding). In this review, we focus on the recent advances of modern breeding strategies and their applications in the maize Breeding 3.0 stage. These modern breeding strategies mainly include marker-assisted selection, genomic selection, genetic engineering, haploid induced breeding, gene editing, and synthetic biology, which act as breeding accelerators and lead to maize improvement in different important traits, such as male sterility, grain yield, grain quality, biotic and abiotic stress resistance, and nitrogen use efficiency. Furthermore, we also propose several promising breeding strategies in the next era of Breeding 4.0, which will improve maize production greatly for ensuring global food security.