Quantitative Trait Loci

Quantitative Trait Loci (QTL) refers to chromosomal regions containing genes that influence polygenic traits—characteristics controlled by multiple genetic loci rather than a single gene. In cannabis breeding, QTL analysis identifies which DNA segments correlate with complex phenotypes such as cannabinoid potency, terpene profiles, flowering time, and plant morphology. Unlike single-gene traits that follow Mendelian inheritance patterns, QTL-controlled traits show continuous variation across populations and are often influenced by environmental factors. Breeders use QTL mapping to understand the genetic architecture underlying commercially important traits and to make more informed crosses. Modern genomic tools have made QTL research increasingly accessible to both academic and commercial breeding programs studying cannabis.

QTL mapping helps breeders identify which genomic regions contribute to desirable polygenic traits, enabling more efficient selection across multiple generations. Understanding QTL architecture supports marker-assisted selection (MAS) and informs strategic outcrossing decisions when targeting complex phenotypes.