title: Genetic Diversity and Population Structure of Two Tomato Species from the Galapagos Islands.
abstract: Endemic flora of the Galapagos Islands has adapted to thrive in harsh environmental conditions. The wild tomato species from the Galapagos Islands,Solanum cheesmaniaeandS. galapagense, are tolerant to various stresses, and can be crossed with cultivated tomato. However, information about genetic diversity and relationships within and between populations is necessary to use these resources efficiently in plant breeding. In this study, we analyzed 3,974 polymorphic SNP markers, obtained through the genotyping-by-sequencing technique, DArTseq, to elucidate the genetic diversity and population structure of 67 accessions of Galapagos tomatoes (compared to twoS. lycopersicumvarieties and oneS. pimpinellifoliumaccession). Two clustering methods, Principal Component Analysis and STRUCTURE, showed clear distinction between the two species and a subdivision in theS. cheesmaniaegroup corresponding to geographical origin and age of the islands. High genetic variation among the accessions within each species was suggested by the AMOVA. High diversity in theS. cheesmaniaegroup and its correlation with the islands of origin were also suggested. This indicates a possible influence of the movement of the islands, from west to east, on the gene flow. Additionally, the absence ofS. galapagensepopulations in the eastern islands points to the species divergence occurring after the eastern islands became isolated. Based on these results, it can be concluded that the population structure of the Galapagos tomatoes collection partially explains the evolutionary history of both species, knowledge that facilitates exploitation of their genetic potential for the identification of novel alleles contributing to stress tolerance.
authors.affiliation: Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology Thuwal, Saudi Arabia.
authors.forename: Yveline
authors.initials: Y
authors.lastname: Pailles
authors.affiliation: Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology Thuwal, Saudi Arabia.
authors.forename: Shwen
authors.initials: S
authors.lastname: Ho
authors.affiliation: Genomics of Plants Stress Unit, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and Instituto de Biologia Experimental e TecnológicaOeiras, Portugal; Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew York, NY, USA.
authors.forename: Inês S
authors.initials: IS
authors.lastname: Pires
authors.affiliation: Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology Thuwal, Saudi Arabia.
authors.forename: Mark
authors.initials: M
authors.lastname: Tester
authors.affiliation: Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology Thuwal, Saudi Arabia.
authors.forename: Sónia
authors.initials: S
authors.lastname: Negrão
authors.affiliation: Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology Thuwal, Saudi Arabia.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Schmöckel
keywords: Galapagos Islands; Solanum cheesmaniae; Solanum galapagense; biogeography; genetic diversity; genotyping-by-sequencing; tomato; wild relatives