ARS | Publication request: Use of DNA sequence data to interpret diversity in tomato

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2012
Publication Date: June 5, 2012
Citation: Labate, J.A., Robertson, L.D. 2012. Use of DNA sequence data to interpret diversity in tomato. Plant Germplasm Operations Committee Meeting. Vol 4, p. 1..

Technical Abstract: Tomato (Solanum lycopersicum L.) has been improved for a larger number of traits through crosses with wild relatives than has any other crop. Beneficial traits transferred into cultivars from wild species have included disease, pest or abiotic stress tolerance or resistance, ease of mechanical harvesting and fruit quality components. In addition, natural hybridization between S. lycopersicum and its closest wild relative Solanum pimpinellifolium has been documented in sympatric populations in Ecuador, Peru and northern Chile. We compared DNA sequences at 47 loci from genotypes of S. lycopersicum and wild tomato species S. pimpinellifolium, Solanum arcanum, Solanum peruvianum, Solanum pennellii and Solanum habrochaites in order to interpret origins of alleles that were apparently introgressed into S. lycopersicum. Cladograms, splits networks, genomic map positions, and historical origins of accessions were used to understand evolutionary patterns at nine of the 47 loci that showed evidence of introgression. We found that four markers were involved in linkage drag during breeding while alleles at five markers apparently originated from natural hybridization with S. pimpinellifolium. The intrinsic value of naturally introgressed germplasm has been recognized in other crops as a source of novel alleles for various traits. If horticultural effects of introgression are subtle then accessions descended from hybrids may be prime sources to screen for new alleles. We conclude that the positive identification of introgressed genes within tomato will help inform conservation and utilization of germplasm diversity. This includes both facilitating the purging of undesirable linkage drag and the exploitation of novel, favorable alleles.