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

Genetics 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 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 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 each genotype's height at a five-day interval. 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 days after planting, whereas several transient QTLs were only detectable within specific shorter periods or at 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.