Revision of wild tomatoes (Solanum sect. Lycopersicon (Mill.) Wettst.) and their outgroup relatives in section Juglandifolium (Rydb.) and section Lycopersicoides (Child) Peralta

PERALTA I. E.; KNAPP S.; SPOONER D. M.

Madison, Wisconsin, USA

Congreso; VI Congreso Internacional de Solanáceas, de la Red de Genómica de Solanáceas y de la Asociación Americana de Papa “Genomics meets Biodiversity” Madison, Wisconsin, Estados Unidos,; 2006

Sociedad Internacional de Solanáceas, Asociación de Genómica de Solanáceas y la Asociación Americana de Papa, Universidad de Wisconsin, Madison, Estados Unidos

Solanum section Lycopersicon includes the cultivated tomato (Solanum lycopersicum) and 12 wild relatives, endemic to western South America from Ecuador to northern Chile, and with two endemic species in the Galápagos Islands; Solanum lycopersicum weedy escaped forms are distributed worldwide. Sister to section Lycopersicon are two species in Solanum section Juglandifolium, distributed in Colombia, Ecuador, and Peru, and sister to these are two species of Solanum section Lycopersicoides, distributed in southern Peru and northern Chile. The delimitation and relationships of wild tomatoes have differed widely depending upon whether morphological or biological species concepts are considered. We summarize our recent taxonomic treatment of section Lycopersicon, section Juglandifolium, and section Lycopersicoides based on morphological and molecular studies. Species are hypotheses of patterns of variation in nature, and we based our species delimitation on a wide data set to understand this variation. Several herbarium specimens of European, South and North American Herbaria, and additional germplasm accessions grown in experimental fields were analyzed. We review species concepts in the tomatoes, and our decisions relied on clear morphological discontinuities to define the easily distinguished species S. habrochaites, S. lycopersicoides, S. pennellii, and S. sitiens. The following likely sister species are generally distinguishable but sometimes intergrade: 1) S. lycopersicum, S. pimpinellifolium, 2) S. cheesmaniae, S. galapagense (sometimes also with introduced S. pimpinellifolium), 3) S. arcanum, S. chmielewskii, S. neorickii, 4) S. corneliomulleri, S. peruvianum, 5) S. chilense, S. huaylasense, 6) S. ochranthum, S. juglandifolium. Potential reasons for variability and intergradation are recent divergence and hybridization. Solanum peruvianum, considered a polymorphic species, is a particularly interesting and complex case. Based on a pragmatic combination of phylogeny and morphology that reflects evolving distinguishable entities, we now recognize four species within this complex taxa. We also identify four “species groups” within section Lycopersicon and propose a new classification.