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N. Schauer et al., "Comprehensive metabolic profiling and phenotyping of interspecific introgression lines for tomato improvement," Nature Biotech, 24:447-54, 2006. (Cited in 51 papers)

To explore the genetics behind tomato nutrition and taste, Alisdair Fernie of the Max Planck Institute of Molecular Plant Physiology and collaborators embarked on the first study of tomato quantitative trait loci (QTL), stretches of DNA that underlie traits of interest. By back-crossing cultivated tomato lines with wild species, they created 76 introgression lines of fruit (ILs) harboring "wild" chromosome segments.

Analysis of the ILs resulted in identification of over 1,200 QTLs, many of which were related to valuable traits like carbohydrate content, plant weight, and seed number. "This was probably the first study of this scale," Fernie wrote in an E-mail, though applying the results to crop improvement can take upwards of 15 years."

The ILs themselves "have become a real central tool in understanding and analyzing various tomato traits," says James Giovannoni, a biologist at the USDA-ARS Plant, Soil and Nutrition Laboratory, and they are now widely used in the community. Previous studies used environmental conditions to generate genetic variation.

Fernie is now working with the European Union-funded project EU-SOL, a collaboration of 40 research groups working to map and characterize important QTLs and genetic markers in tomatoes that underlie traits such as flavor, fragrance, and shelf-life. EU-SOL is also involved in sequencing the tomato genome, an international project that could someday help refine molecular breeding strategies.