Dominant Alleles

Dominant alleles are genetic variants that express their phenotypic trait when present in either one or two copies of a gene, masking recessive alleles on the homologous chromosome. In cannabis breeding, understanding dominance relationships is fundamental to predicting offspring traits across generations. Breeders working with dominant traits—such as certain morphologies, flowering responses, or terpene production markers—can reliably produce consistent phenotypes by crossing carriers with the dominant allele. Mendelian inheritance patterns show that a dominant trait will appear in approximately 75% of F2 generation plants when both parents are heterozygous. Mapping dominant loci has become increasingly relevant as breeders seek to stabilize desirable characteristics and reduce phenotypic variance in commercial cultivars.

Breeders leverage dominant alleles to rapidly fix desirable traits in breeding lines, since homozygous dominant and heterozygous individuals both express the phenotype. Selecting for dominant markers accelerates stabilization timelines compared to recessive trait breeding, making them strategically valuable in multi-generational improvement programs.