As global population growth and environmental pressures intensify, ensuring stable food supplies has become increasingly difficult and urgent. Wheat is a cornerstone of global food security, providing a major source of calories for nearly 40% of the world's population. Yield improvement, however, depends not only on agronomic inputs but also on plant architecture, which governs light interception, space competition, and performance under dense planting. Traits such as plant height, tiller number, and tiller angle collectively shape canopy structure and resource-use efficiency. During the Green Revolution, semi-dwarfing genes revolutionized wheat breeding by reducing plant height and thereby enhancing lodging resistance and yield stability, yet their broader effects on plant architecture have remained poorly understood.
Addressing on this gap in knowledge, Dr. Han Zhang from Shandong Agricultural University, China, along with his colleagues, conducted this study to better understand how foundational breeding genes shape wheat growth beyond their traditionally recognized roles. The study was made available online on December 09, 2025 in The Crop Journal .
"We identified the Green Revolution allele Rht-D1b as a major regulator of tiller angle in wheat. Beyond reducing plant height, Rht-D1b was shown to increase tiller angle and tiller number—two traits that directly shape canopy structure and light interception," shares Zhang. "Mechanistically, Rht-D1b negatively regulates shoot gravitropism by altering lateral auxin transport, supported by changes in the expression of auxin signaling and transport genes."
Notably, the effects of Rht-D1b were dosage-dependent: moderate expression optimized plant architecture and increased grain yield per plant, while both loss-of-function and strong overexpression resulted in yield penalties.
The team's findings have direct practical relevance. Moderate expression of Rht-D1b under its native promoter improves grain yield per plant, highlighting the importance of optimal gene dosage in breeding applications. More broadly, this study provides breeders with new genetic tools to fine-tune canopy architecture.
"By consciously selecting specific combinations of Rht alleles, breeders can achieve not only reduced height and lodging resistance but also ideal tiller angle and tiller number. This translates to increased productivity and profitability per hectare," says Zhang. "For consumers and global food security, it means a more resilient and efficient wheat supply, helping to meet the rising demand for staple food in a sustainable manner."
In conclusion, this study reframes Rht-D1b as a central coordinator of wheat architecture rather than solely a height-reducing gene. By revealing how Green Revolution alleles shape canopy structure through pleiotropic effects, the work bridges fundamental plant biology with applied crop improvement. These insights lay a strong foundation for next-generation wheat breeding strategies aimed at maximizing yield, resilience, and sustainability in a changing world.
