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Gene duplication and divergence affecting drug content in Cannabis sativa
Author(s) -
Weiblen George D.,
Wenger Jonathan P.,
Craft Kathleen J.,
ElSohly Mahmoud A.,
Mehmedic Zlatko,
Treiber Erin L.,
Marks M. David
Publication year - 2015
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13562
Subject(s) - biology , quantitative trait locus , genetics , locus (genetics) , gene duplication , gene , cannabinoid , population , functional divergence , genetic linkage , phenotype , allele , gene family , gene expression , demography , receptor , sociology
SummaryCannabis sativa is an economically important source of durable fibers, nutritious seeds, and psychoactive drugs but few economic plants are so poorly understood genetically. Marijuana and hemp were crossed to evaluate competing models of cannabinoid inheritance and to explain the predominance of tetrahydrocannabinolic acid ( THCA ) in marijuana compared with cannabidiolic acid ( CBDA ) in hemp. Individuals in the resulting F 2 population were assessed for differential expression of cannabinoid synthase genes and were used in linkage mapping. Genetic markers associated with divergent cannabinoid phenotypes were identified. Although phenotypic segregation and a major quantitative trait locus ( QTL ) for the THCA / CBDA ratio were consistent with a simple model of codominant alleles at a single locus, the diversity of THCA and CBDA synthase sequences observed in the mapping population, the position of enzyme coding loci on the map, and patterns of expression suggest multiple linked loci. Phylogenetic analysis further suggests a history of duplication and divergence affecting drug content. Marijuana is distinguished from hemp by a nonfunctional CBDA synthase that appears to have been positively selected to enhance psychoactivity. An unlinked QTL for cannabinoid quantity may also have played a role in the recent escalation of drug potency.