Genetic Advances in Cannabis sativa L.: A Review of Recent Progress and Future Directions

Cannabis sativa L. has transitioned from an understudied crop to a subject of intense genomic investigation. Historically, research was severely limited by legal restrictions and a reliance on phenotypic selection. However, the recent legalization of industrial hemp in many regions has catalyzed a surge in genomic resources, including high-quality reference genomes and pangenomic frameworks. These tools are now being used to dissect the complex genetic architecture of traits such as cannabinoid biosynthesis, sex determination, fiber quality, and stress resilience.

Cannabis is a diploid species (2n=20) with a complex genome characterized by a high proportion of repetitive DNA, particularly retrotransposons. This genomic complexity, combined with the plant's dioecious nature and heteromorphic sex chromosomes, has historically complicated assembly and mapping efforts. Recent progress in long-read sequencing and chromatin conformation capture has enabled the development of chromosome-level assemblies. These resources have clarified the organization of cannabinoid synthase loci and provided insights into the evolution of the species. Furthermore, genome-wide association studies (GWAS) and quantitative trait loci (QTL) mapping are identifying the genetic basis of agronomic traits, moving the field toward a more mechanistic understanding of how genotype influences phenotype.

Bridging the gap between gene discovery and cultivar development requires functional validation. While the plant has historically been recalcitrant to genetic manipulation, recent breakthroughs in transient expression systems—such as virus-induced gene silencing (VIGS) and agroinfiltration—have provided rapid tools for testing gene function. Additionally, the first successful stable CRISPR/Cas9-mediated genome editing in hemp has established a proof-of-concept for precise trait engineering. These functional tools are now being integrated into molecular breeding pipelines, including marker-assisted selection (MAS) and genomic selection (GS), to accelerate the development of elite genotypes optimized for specific industrial and medicinal applications.