QTL Mapping Reveals the Genetic Architecture of Biomechanical Properties in Sorghum.

Mechanical characterization is an important and now frequently used tool for phenotyping plants for crop improvement. Structural and mechanical engineering as well as materials science can be applied to plants to study the mechanical behavior of plants stems. The inherent mechanical properties of plant structures such as the stem are relevant to breeding strategies, aiming to tackle issues such as crop lodging due to stem or root lodging. While empirical tests of breaking strength and stiffness have been applied to plants, few of these studies consider the genetic background of the plants examined. In this study, we report for the first time on the mapping of QTL for mechanical traits in sorghum in three RIL mapping populations from crosses between grain and sweet sorghum parents. The genetic architecture of biomechanical traits in the three RIL populations appear to be quantitative and pleiotropic. Eight QTL affecting mechanical and morphological traits were detected; two of these QTL were consistently found in all populations and co-located with previously cloned dwarfing genes Dw1 and Dw3. These results suggest that dwarfing genes affect the mechanical properties of sorghum and ultimately their lodging resistance while also having a profound impact on the stem’s morphology and geometry.