Plant 93

Solanum lycopersicum L. (Solanaceae)



Tomatoes have been part of European life for fewer than 500 years. The rise of tomatoes as flexible ingredients in the European kitchen came on the back of deep suspicions that they were poisonous or at best of only ornamental value.

Eighteenth-century English botanist Philip Miller placed tomatoes into the genus Lycopersicon, a small group distributed from the southwestern Andes and Galapagos Islands, whilst the Swedish botanist Carolus Linnaeus included tomatoes in the very large genus Solanum; modern DNA-based analyses favour Linnaeus's view.

Tomatoes appear to have been domesticated in two phases. The first phase of domestication occurred in Ecuador and northern Peru and involved the transformation of the wild, tiny-fruited Solanum pimpinellifolium into weedy Solanum lycopersicum var. cerasiforme, somewhat akin to the cherry tomato. During a second Central American phase of domestication, this weedy tomato became the tomato with which we are familiar today.

We do not know when the Spanish brought the tomato to Europe but by the end of the sixteenth century, the English herbalist John Gerard was referring to them as 'apple of Loue' or 'Poma Amoris', whilst John Parkinson reported the English 'onely haue them [tomatoes] for curiosity … and for the amorous aspect or beauty of the fruit'.

Thousands of tomato cultivars have been bred for growing under diverse conditions for diverse uses, including pulping, drying and juicing. As few as four genes appear to be responsible for the eight broad classes of tomato shape, which range from the flattened beefsteak through rectangular plum and familiar round types to heart- and pear-shaped types. Tomatoes are usually thought of as being red, although they can be everything from orange and yellow to dark purple, with individual fruits varying greatly in size from 5 mm to 10 cm diameter.

Tomatoes were a cause of suspicion as sceptical European consumers have become concerned about revolutionary plant breeding technologies. Tomatoes were the first genetically modified plants endorsed for human consumption. The Flavr Saver tomato was genetically modified to slow the ripening process whilst retaining its natural colour and flavour. Released in the United States of America in 1994, the tomato was withdrawn from commercial sale in 1997. At a similar time, in the United Kingdom, a separate genetic modification was incorporated into a tomato used for paste production. The paste was commercially successful but was withdrawn as mistrust over genetically modified food became widespread in Britain and Europe.

Further reading

Blanca J et al. 2012. Variation revealed by SNP genotyping and morphology provides insight into the origin of the tomato. PLoS ONE 7: e48198.

Martineau B 2001. First fruit: the creation of the Flavr Savr tomato and the birth of biotech food. McGraw-Hill Education.

Monforte AJ et al. 2014. The genetic basis of fruit morphology in horticultural crops: lessons from tomato and melon. Journal of Experimental Botany 65: 4625-4637.

Peralta IE et al. 2008. Taxonomy of wild tomatoes and their relatives (Solanum sect. Lycopersicoides, sect. Juglandifolia, sect. Lycopersicon; Solanaceae). American Society of Plant Taxonomists.

Stephen Harris