2025/11/26 by Trevor Pougnet, David H. Suchoff, C. S. Shih +4 · 1 voice
Biochemistry, Genetics and Molecular Biology · Medicine · Agricultural and Biological Sciences · #Plant tissue culture and regeneration #Cannabis and Cannabinoid Research #Chromosomal and Genetic Variations
paper · doi:10.21273/hortsci18920-25
openalex publication_date 2025/11/26 · openalex created_date 2025/11/27 · openalex updated_date 2026/07/22
Ploidy manipulation has been used in the breeding of hemp ( Cannabis sativa L.; 2 n = 2 x = 20), for infertility, biomass, cannabinoid production, and other agricultural traits. Induction, characterization, and hybridization compatibility of diploid (2 x ), triploid (3 x ), and tetraploid (4 x ) hemp have been researched, and cultivars with those ploidy levels have been released. However, research on hexaploid (6 x ) or pentaploid (5 x ) hemp has not been reported yet. In the present study, a female hexaploid was generated from a triploid clone by in planta colchicine treatments. Of 23 triploid clones treated, two were converted to stable hexaploid, and no triploid cells were detected after three clonal generations by flow cytometry. Ploidy was further confirmed by chromosome counting. Characterization of the hexaploid plants was compared with their triploid version. The hexaploids showed significantly reduced growth rates, fresh biomass, dry biomass, plant height, stem caliper, dry flower yield, and total cannabinoid and terpene content of flowers. The hexaploids exhibited asymmetrical compatibility and fertility, being conditionally fertile as a female parent and infertile as a male parent. A high compatibility of 6 x × 4 x was observed, with an average of 117 seeds developed per pollinated plant; in contrast, a low compatibility of 6 x × 2 x was observed, with an average of six seeds developed per plant. When pollinated by tetraploid plants, the hexaploids showed 12 times more seeds per plant than the triploid. No seed was obtained by 6 x × 6 x crosses, and all pollen from hexaploid plants showed empty and malformed grains by fluorescein diacetate staining. Ploidies of seedlings were investigated, and seedlings from 6 x × 4 x were all pentaploid, while seedlings from 6 x × 2 x were tetraploid or pentaploid. The research demonstrates the production of hexaploid hemp from triploids and characterizes their traits and fertility in interploid hybridizations, as well as the production of pentaploid hemp.