This tobacco (Nicotiana tabacum) relative was first planted in the SCIence Garden in the summer of 2018. It was grown from seed by Peter Grimbly, SCI Horticulture Group member. Although normally grown as an annual, some of the SCIence Garden plants have proven to be perennial. It is also gently self-seeding across the garden. It is native to the south and southeast of Brazil and the northeast of Argentina but both the species and many cultivars of it are now grown ornamentally across Europe. Flower colour is normally white, but variants with lime green and pink through to darker red flowers are available.
Like many Nicotiana this species has an attractive floral scent in the evening and through the night. The major component of the scent is 1.8-cineole. This constituent has been shown to be a chemical synapomorphy for the particular section of the genus Nicotiana that this species sits within (Raguso et al, Phytochemistry 67 (2006) 1931-1942). A synapomorphy is a shared derived character – one that all descendants and the shared single ancestor will have.
This ornamentally and olfactorily attractive plant was chosen for the SCIence Garden to represent two other (arguably less attractive) Nicotiana species.
Firstly, Nicotiana benthamiana, a tobacco species from northern Western Australia. It is widely used as a model organism in research and also for the “pharming” of monoclonal antibodies and other recombinant proteins.
In a very topical example of this technology, the North American biopharmaceutical company Medicago is currently undertaking Phase 1 clinical trials of a Covid-19 vaccine produced using their plant-based transient expression and manufacturing technology.
Secondly, Nicotiana tabacum, the cultivated tobacco which contains nicotine. This alkaloid is a potent insecticide and tobacco was formerly widely used as a pesticide.
This vivid extract from William Dallimore’s memoirs of working at Royal Botanic Gardens, Kew illustrate how tobacco was used in the late Victorian era.
“Real tobacco was used at Kew for fumigating plant houses. It was a very mixed lot that had been confiscated by excise officers, and it was said that it had been treated in some way to make it unfit for ordinary use before being issued to Kew. With the men working in the house ten men were employed on the job. After the first hour the atmosphere became unpleasant and after 1 ½ hours the first casualties occurred, some of the young gardeners had to leave the house. At the conclusion there were only the two labourers the stoker and one young gardener to leave the house, I was still about but very unhappy. Each man employed at the work, with the exception of the foreman, received one shilling extra on his week’s pay.“
After a second such fumigation event it was reported that there was a great reduction in insect pests, particularly of mealy bug and thrips, with a “good deal of mealy bug” falling to the ground dead.
Health and safety protocols have improved since the Victorian era, but the effectiveness of nicotine as an insecticide remains. From the 1980’s through the 1990’s a range of neo-nicotinoid plant protection agents were developed, with structures based on nicotine. Although extremely effective, these substances have also been shown to be harmful to beneficial insects and honey bees. Concerns over these adverse effects have led to the withdrawal of approval of outdoor use in the EU.
Imidacloprid – the first neo-nicotinoid developed
In early 2020, the European commission decided not to renew the European license for the use of Thiacloprid in plant protection, making it the fourth neo-nicotinoid excluded for use in Europe.
Where the next generation of pest control agents will come from is of vital importance to the horticulture and agriculture industries in the UK and beyond and the presence of these plants in the garden serves to highlight this.