Toward Breeding by Gene Design: Constructing the Ideotype of Sorghum (Sorghum bicolor (L.) Moench) Adapted for Modern Agricultural Production

Sorghum (Sorghum bicolor (L.) Moench) is an essential food, forage, and bioenergy crop that plays an irreplaceable role in modern agricultural supply systems and daily life. However, the traditional cultivation varieties, characterized by tall stems, low planting density and large panicles, are incompatible with the requirements of modern intensive agriculture for high-density planting, mechanized harvesting, and efficient resource utilization. Therefore, cultivating an ideotype suitable for mechanized harvesting is the most urgent and practical need for sorghum breeding. This paper systematically reviews the key components of the sorghum ideotype and their physiological basis, focusing on traits such as canopy structure, stalk characteristics, panicle traits, and root systems. Then, the major genes and molecular mechanisms that regulate plant height, stem strength, leaf morphology, and panicle type are described in detail. Additionally, current breeding challenges, including gene pleiotropy, trade-offs among traits, narrow genetic diversity, and limitations in phenotypic identification techniques, are summarized. Finally, we propose modern breeding strategies involving multi-omics approaches, high-throughput phenotyping, gene editing, and computational modeling to advance sorghum breeding into the design era. This will enable the simultaneous improvement in light use efficiency, lodging resistance, and adaptation to mechanized production.