“QTL Mapping of Stem Biochemical Traits and Precision Phenotyping in Bioenergy Sorghum (Sorghum bicolor)”

Dr. Francisco Gomez
Department of Plant and Microbial Biology
NC State University

Abstract

Understanding the genetic architecture of important mechanical traits is critically important to application in plant breeding. Mechanical characterization is an important and now frequently used tool for phenotyping plants for crop improvement, e.g. lodging resistance. Mechanics of materials and structures in response to various external stimuli as well as information of basic building blocks that constitute the plants can be applied to study the mechanical behavior of plant stems. Here 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. Six QTL affecting mechanical and morphological traits were detected; two of these QTL were consistently found in all populations and co-localized 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. We also demonstrate a new high-throughput pipeline to measure morpho-anatomical traits using an x-ray computed tomography (CT) in an applied sorghum breeding program.  CT estimates were highly predictive of morphological traits and moderately predictive of anatomical traits. Our approach demonstrates that CT can be a powerful tool to quantify important internal and external phenotypic information of plant stems.