The Solanaceae, also called nightshades, comprise more than 3000 species many of which evolved in the Andean/Amazonian regions of South America in habitats that vary dramatically and include rain forests that receive more than 3 meters of rainfall annually to deserts with virtually no rainfall and high mountains with regular snowfall and subfreezing temperatures.

The center of diversity of the Solanaceae is near the equator and thus species were undisturbed by the ice ages and have had time to accumulate adaptive genetic variation for extreme ecological niches. The Solanaceae are also the third most important plant taxon economically and the most valuable in terms of vegetable crops, and are the most variable of crops species in terms of agricultural utility, as it includes the tuber-bearing potato, a number of fruit-bearing vegetables (tomato, eggplant, peppers), ornamental plants (petunias, Nicotiana), plants with edible leaves (Solanum aethiopicum, S. macrocarpon) and medicinal plants (eg. Datura, Capsicum).

Solanaceaous crops have been subjected to intensive human selection, allowing their use as models to study the evolutionary interface between plants and people. The ancient mode of Solanaceae evolution, coupled with an exceptionally high level of conservation of genome organization at the macro and micro levels make the family a model to explore the basis of phenotypic diversity and adaptation to natural and agricultural environments.

Some Solanaceae plants are important model systems for biology; these include tomato for fruit ripening and plant defense, tobacco for plant defense, and petunia for the biology of anthocyanin pigments.

Recently, the phylogenetic classification of the Solanaceae has been revised. The genus Lycopersicon was re-integrated into the Solanum genus, as had been the case in Linnaeus' classification.

Today, the International SOL project attempts to study the basis of diversity and adaptation in the Solanaceae as a model for biology. One of the cornerstones of the SOL project is the sequencing of the complete euchromatic region of the tomato genome.

Solanaceae phylogenetic tree

Below is an overview of the phylogeny of the Solanaceae (incl. coffee), kindly provided by Feinan Wu, based on Bohs and Olmstead, (1997).

Further documents

• An overview of changes in the Solanum nomenclature. Kindly provided by Prof Sandra Knapp of the Natural History Museum, London, UK.
• Links to other Solanaceae resources are provided on our Solanaceae links page.
• An analysis of codon usage for Tomato and potato including codon usuage tables.

References

Bohs L., Olmstead R. G. (1997) Phylogenetic relationships in Solanum (Solanaceae) based on ndhF sequences. Syst. Bot. 22: 5-17.