Genomic characterization of a wild-like tomato accession found in Arizona; a northward migration story

Tomato domestication history has been revealed to be a highly complex story. A major contributor to this complexity is an evolutionary intermediate group (Solanum lycopersicum var. cerasiforme (Alef.) Voss; SLC) between the domesticated tomato (Solanum lycopersicum var. lycopersicum L.; SLL) and its wild relative (Solanum pimpinellifolium L.; SP). SLC includes accessions with a broad spectrum of genomic and phenotypic characteristics. Some of the SLC accessions were previously hypothesized to be spreading northward from South America into Mesoamerica and that migration probably entailed reversal to wild-like phenotypes such as smaller fruits. Prior to this study, the northernmost confirmed extension of the SLC was limited to northern Mexico. In this study, we employed genomic methods to investigate the origin of a wild-like tomato found in a garden in Scottsdale Arizona, USA. The so-called “Arizona tomato” featured a vigorous growth habit and carried small fruits weighing 2-3 grams. Our phylogenomic analyses revealed the identity of the Arizona tomato as a member of the Mexican SLC population (SLC MEX). To our knowledge, this is the first report of an SLC accession, confirmed using genomics, growing spontaneously in Arizona. This finding could have implications for conservation biology as well as agriculture.