PT  - JOURNAL ARTICLE
AU  - Christopher J. Grassa
AU  - Jonathan P. Wenger
AU  - Clemon Dabney
AU  - Shane G. Poplawski
AU  - S. Timothy Motley
AU  - Todd P. Michael
AU  - C.J. Schwartz
AU  - George D. Weiblen
TI  - A complete <em>Cannabis</em> chromosome assembly and adaptive admixture for elevated cannabidiol (CBD) content
AID  - 10.1101/458083
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 458083
4099  - http://biorxiv.org/content/early/2018/12/11/458083.short
4100  - http://biorxiv.org/content/early/2018/12/11/458083.full
AB  - Cannabis has been cultivated for millennia with distinct cultivars providing either fiber and grain or tetrahydrocannabinol. Recent demand for cannabidiol rather than tetrahydrocannabinol has favored the breeding of admixed cultivars with extremely high cannabidiol content. Despite several draft Cannabis genomes, the genomic structure of cannabinoid synthase loci has remained elusive. A genetic map derived from a tetrahydrocannabinol/cannabidiol segregating population and a complete chromosome assembly from a high-cannabidiol cultivar together resolve the linkage of cannabidiolic and tetrahydrocannabinolic acid synthase gene clusters which are associated with transposable elements. High-cannabidiol cultivars appear to have been generated by integrating hemp-type cannabidiolic acid synthase gene clusters into a background of marijuana-type cannabis. Quantitative trait locus mapping suggests that overall drug potency, however, is associated with other genomic regions needing additional study.Resources available online at: http://cannabisgenome.orgSummary A complete chromosome assembly and an ultra-high-density linkage map together identify the genetic mechanism responsible for the ratio of tetrahydrocannabinol (THC) to cannabidiol (CBD) in Cannabis cultivars, allowing paradigms for the evolution and inheritance of drug potency to be evaluated.