Persistent and transient QTLs underlying growth trajectory of plant height in sorghum

Genetic studies based on end-of-season measurements focus only on the outcome of a complex and dynamic process. Uncovering the genetic basis underlying the temporal dynamics of plant height will enhance our understanding of the genotype-to-phenotype relationship. Here, we conducted functional mapping to investigate the temporal dynamics of plant height using the time-series data extracted from unmanned aerial vehicle (UAV)-based RGB imagery from two sorghum populations. Significant correlations were found between the UAV-derived measurements and manual measurements. We modeled the growth trajectory using a logistic function. Among quantitative trait loci (QTLs) identified by mapping with the growth curve parameters as derived traits, several were co-localized with known genes controlling plant height. To further visualize the temporal patterns of genetic effects, we used the logistic function to estimate the height of each genotype at 5 d intervals. Genome scans of the model-estimated heights detected QTLs with dynamic effect changes across development. Persistent QTLs, co-localizing with Dw1, Dw2, Dw3, and qHT7.1, were detectable starting from 40 d after planting, whereas several transient QTLs were only detectable within specific shorter periods or during some growing seasons. These findings enabled us to generate a conceptual figure to depict six potential dynamic patterns of persistent and transient QTLs underlying growth trajectories.