Filogenia Del Genero Solanum

Systematic Botany (2007), 32(2): pp. 445–463 # Copyright 2007 by the American Society of Plant Taxonomists

A Three-Gene Phylogeny of the Genus Solanum (Solanaceae)
TERRI L. WEESE and LYNN BOHS1
University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, Utah 84112 U.S.A. 1 Author for correspondence (bohs@biology.utah.edu) Communicating Editor: Andrea SchwarzbachABSTRACT. Solanum, with approximately 1,500 species, is the largest genus in the Solanaceae and includes economically important species such as the tomato, potato, and eggplant. In part due to its large size and tropical center of diversity, resolving evolutionary relationships across Solanum as a whole has been challenging. In order to identify major clades within Solanum and to gain insight intophylogenetic relationships among these clades, we sampled 102 Solanum species and seven outgroup taxa for three DNA sequence regions (chloroplast ndhF and trnTF, and nuclear waxy) and analyzed the data using parsimony and Bayesian methods. The same major Solanum clades were identified by each data partition, and the combined analysis provided the best resolved hypothesis of relationships within thegenus. Our data suggest that most traditionally recognized Solanum subgenera are not monophyletic. The Thelopodium clade is sister to the rest of Solanum, which is split into two large clades. These two large clades are further divided into at least 10 subclades, for which informal names are provided and morphological synapomorphies are proposed. The identification of these subclades provides aframework for directed sampling in further phylogenetic studies, and identifies natural groups for focused revisionary work. KEYWORDS: Eggplant, ndhF, potato, tomato, trnT-F, waxy.

Among seed plants, about 20 genera are thought to contain 1,000 or more species each (Frodin 2004). These ‘‘giant genera’’ present both problems and opportunities for plant systematists. Their size makes it difficult, ifnot impossible, for a single researcher to study them in their entirety, with the result that many have been ignored or avoided by taxonomists, lack full or even partial revisionary treatments, and have not been examined phylogenetically. On the other hand, giant genera represent unprecedented opportunities to investigate numerous morphological, biogeographical, developmental, and molecularquestions within monophyletic and hyperdiverse groups. Some giant genera are artifacts of taxonomic neglect (‘‘garbage groups’’), whereas others are held together by striking synapomorphies (‘‘key characters’’) that may be indicative of rapid diversification. In order to make these large genera tractable for further study, their monophyly and component clades must be established and described. Morefocused studies can then be accomplished on smaller monophyletic groups within the giant genera. Solanum is one such giant genus. Thought to encompass some 1,250 to 1,700 species, it is the largest genus in Solanaceae and within the top 10 most species-rich seed plant genera (Frodin 2004). Solanum is unique in the family in possessing anthers that open by terminal pores and flowers that lack thespecialized calyx found in the related genus Lycianthes, which also has poricidal anther dehiscence. Species of Solanum occur on all temperate and tropical continents and exhibit remarkable morphological and ecological diversity. Solanum is arguably the most economically important genus of

plants, containing familiar crop species such as the tomato (S. lycopersicum), potato (S. tuberosum L.), andeggplant (S. melongena), as well as many minor food plants and species containing poisonous or medicinally useful secondary compounds. Various species of Solanum, especially the tomato and potato, have served as model organisms for the investigation of many questions in cell and developmental biology and genetics, and currently S. lycopersicum is the focus of an entire-genome sequencing effort...