In vitro-induced polyploidy and its effect on horticultural characteristics, essential oil composition and bioactivity of Tetradenia riparia

• Methods for the induction of polyploidy and verification using flow cytometry, were developed.
• Tetraploid plants were morphologically distinct from the diploids.
• Tetraploid T.riparia plants had more essential oil and a different essential oil profile compared with the diploids.
• First report of bioactivity against a plant pathogenic fungus of postharvest concern.

Tetradenia riparia, a medicinal aromatic shrub with multiple uses, occurs throughout tropical Africa and as far south as South Africa. In vitro-induced polyploidy of T. riparia was carried out by treating seeds with colchicine and subsequently verifying the duplication of chromosomes using flow cytometry. Significant differences between diploid and tetraploid plants in terms of leaf morphology, essential oil content and characterisation as well as in vitro bioactivity against Geotrichum candidum, a fungal species causing postharvest rot in fruit and vegetables, were recorded. Tetraploid plants produced essential oil with the potential for mitigating postharvest diseases. This is the first report on the bioactivity of T. riparia essential oil against a plant pathogenic fungal species of postharvest concern.