Overview of research on growth angle of seminal root in wheat genotypes

Abstract

Since the identification of the DRO1 gene in rice in 2011, which regulates root gravitropism, research on the genetic control of root angle has expanded to wheat. Unlike rice, which has a major gene like DRO1, wheat lacks such a single dominant gene. Instead, its root angle is a complex trait controlled by multiple genes. Studies have demonstrated that the seminal root angle in seedlings can be associated with root distribution at later growth stages, particularly in shallow soil layers. However, this relationship varies depending on the methods used to assess root growth angles and the specific field conditions. Among the various evaluation techniques, the basket and clear pot methods using soil have proven more effective for predicting root system architecture in the field. Wheat lines with contrasting root depths have been developed. The link between root angle and yield remains inconclusive. One study reported that shallow-rooted lines yielded 15% more under waterlogged conditions, although this difference was not statistically significant. Additionally, under long-term no-till management, shallow-rooted lines have shown significantly higher yields in some cases. Roots exhibit high plasticity and adapt to their soil environment. Future research should focus on identifying optimal root system architectures for specific environments and developing wheat cultivars with ideal root traits by pyramiding multiple genetic loci.