A new genetic linkage map of tomato based on a Solanum lycopersicum x S. pimpinellifolium RIL population displaying locations of candidate pathogen response genes

摘要

The narrow genetic base of the cultivated tomato, Solanum lycopersicum L., necessitates introgression of newvariation from related species. Wild tomato species represent a rich source of useful genes and traits. Exploitation of ge-netic variation within wild species can be facilitated by the use of molecular markers and genetic maps. Recently we iden-tified an accession (LA2093) within the red-fruited wild tomato species Solanum pimpinellifolium L. with exceptionallydesirable characteristics, including disease resistance, abiotic stress tolerance, and high fruit lycopene content. To facilitategenetic characterization of such traits and their exploitation in tomato crop improvement, we developed a new recombinantinbred line (RIL) population from a cross between LA2093 and an advanced tomato breeding line (NCEBR-1). Further-more, we constructed a medium-density molecular linkage map of this population using 294 polymorphic markers, includ-ing standard RFLPs, EST sequences (used as RFLP probes), CAPS, and SSRs. The map spanned 1091 cM of the tomatogenome with an average marker spacing of 3.7 cM. A majority of the EST sequences, which were mainly chosen basedon the putative role of their unigenes in disease resistance, defense-related response, or fruit quality, were mapped ontothe tomato chromosomes for the first time. Co-localizations of relevant EST sequences with known disease resistancegenes in tomato were also examined. This map will facilitate identification, genetic exploitation, and positional cloning ofimportant genes or quantitative trait loci in LA2093. It also will allow the elucidation of the molecular mechanism(s)underlying important traits segregating in the RIL population. The map may further facilitate characterization and exploita-tion of genetic variation in other S. pimpinellifolium accessions as well as in modern cultivars of tomato.