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