Aneuploidy

Aneuploidy refers to an abnormal chromosome number in cannabis plants, occurring when the standard diploid set (2n) is altered by the gain or loss of individual chromosomes rather than whole sets. Cannabis typically maintains a chromosome count of 2n=20 in female plants and 2n=19 in males due to sex-determining mechanisms. Aneuploid conditions—such as trisomy (one extra chromosome) or monosomy (one missing chromosome)—can arise spontaneously during meiosis, through pollination errors, or tissue culture protocols. While aneuploid plants may exhibit reduced vigor, altered morphology, or fertility challenges, they occasionally produce novel trait combinations that breeders monitor during selection. Understanding aneuploidy is important for maintaining genetic stability in seed lines and recognizing aberrant phenotypes that may appear in breeding populations.

Breeders working with large-scale seed production or tissue culture protocols track aneuploidy rates as a quality-control marker, since aneuploid offspring typically show reduced viability or vigor. Accidental aneuploid events are generally minimized rather than selected for, though researchers studying cannabis genetics occasionally examine aneuploid individuals to understand chromosome-specific