Advances in Cannabis Genomics Research

Written by Sabina Pulone

Cannabis is one of the oldest domesticated crops and it has been used since ancient times both for fiber as well as for its active compounds. Scientific research on cannabis has been hindered by legislation restricting its cultivation. Nowadays, with the relaxation of regulations, more studies can be done to understand and reveal the biology of this valuable plant. A recent review paper summarized the recent advances in cannabis genomics research. [1]

Cannabis has been said to have three species with different phenotypic traits: C. sativa L., C. indica Lam. and C. ruderalis. [2] However, the most accepted genetic theory is that the Cannabis genus contains only a single species, C. sativa L. [3]

This plant is dioecious, but feminized seeds can be produced by chemical treatment with silver nitrate and the ethylene hormone inhibitor silver thiosulfate. [4] This method allows the breeding and creation of new cannabis chemovars, ensuring self- or cross-pollination among different cannabis varieties.

Modern breeding technologies are improving traits for medicinal cannabis such as the stability of cannabinoid concentrations over the same chemovar. Nevertheless the poor understanding of cannabis genomics so far, the clandestine breeding that limited genetic diversity, and the plant’s illegality prevented the sharing of cannabis genetics resources and the circulation of scientific information about the plant.

Modern genomic analyses using high-throughput sequencing and single nucleotide polymorphism (SNP) marker-based genotyping platforms have largely improved our understanding of the complex genomic traits of many plant species. High-throughput SNP technology identified errors in cultivar classification by breeders, such as the distinction between hemp and medical cannabis resulting from selective breeding. [5] SNP technology also demonstrated the association between chemotype and differences in loci encoding cannabinoid synthases.

Cannabis genome assemblies revealed through technologies, such as Single-Molecule Real-Time (SMRT) long-read sequencing (PacBio), and MinION (Oxford Nanopore Technologies), largely improved our understanding regarding cannabinoid biosynthetic pathways, confirming the inheritance of these genes. Short-read sequencing technologies may produce deceptive signals since there’s significant similarities between cannabinoid synthase gene loci, whereas long-read sequencing technologies enable a more accurate identification and quantification.

Another achievement of genomic studies is the identification of sex-chromosomes in the cannabis genome; the identification of male and female cannabis plants at an early stage facilitates the overall management of cannabis crops, improving the yield and quality of the cultivated cannabis chemovars.

Cannabis terpene synthases involved in mono- and sesquiterpene production in different cultivars have been identified using a technique called gene co-expression network analysis, but more studies are needed to highlight the expression patterns of minor cannabinoids and other cannabis chemical constituents. [6]

Omics technologies such as transcriptomics, phenomics, metabolomics, and proteomics are characterizing and quantifying pools of biological molecules that regulate the structure, function, and dynamics of cannabis. Our understanding of gene functioning, regulatory networks, and biological and metabolic pathways, together with the advancements in breeding practices, are progressively characterizing cannabis and improving its downstream polyhedral applications.



[1] Hurgobin B, Tamiru-Oli M, Welling M, Doblin M, Bacic A, et al. Recent advances in Cannabis sativa genomics research. New Phytologist. 2021;230(1):73-89. nph. [journal impact factor = 10.151; times cited = 26]


[2] Sawler J, Stout JM, Gardner KM, Hudson D, Vidmar J, et al. The genetic structure of marijuana and hemp. PloS ONE. 2015;10:e0133292. [journal impact factor = 3.24; times cited = 184] [3] Small E, Cronquist A. A practical and natural taxonomy for Cannabis. Taxon. 1976;25(4):405-435. [journal impact factor = 2.68; times cited = 248]


[4] Lubell JD, Brand MH. Foliar sprays of silver thiosulfate produce male flowers on female hemp plants. Horttechnology. 2018;28:743–747. [journal impact factor = 1.087; times cited = 19]


[5] Soorni A, Fatahi R, Haak DC, Salami SA, Bombarely A. Assessment of genetic diversity and population structure in Iranian cannabis germplasm. Scientific Reports. 2017;7:15668. [journal impact factor = 4.380; times cited = 46] [6] Zager JJ, Lange I, Srividya N, Smith A, Lange BM. Gene networks underlying cannabinoid and terpenoid accumulation in Cannabis. Plant Physiol. 2019;180(4):1877-1897. [journal impact factor = 8.340; times cited = 57]


Image: https://pixabay.com/it/photos/cannabis-verde-azienda-agricola-4633192/

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Sabina Pulone

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