A Consensus Genetic Map and Linkage Panel for Fresh-market Tomato

The first consensus genetic map in fresh-market tomato (Solanum lycopersicum) was constructed, combining genetic recombination data from two biparental F2 segregating populations derived from four different fresh-market tomatoes. Each F2 population was nominated by different academic tomato breeding programs located in major fresh-market tomato-producing areas of the United States, and chromosome-wide variation in recombination rates was observed between tomato populations based on the origin of their breeding programs. A consensus map constructed using 335 common single nucleotide polymorphism (SNP) sites found in both populations spanned 737.3 cM across 12 tomato chromosomes, with chromosome 2 containing more than 40% of the total SNPs and chromosomes 4, 5, 7, and 10 together representing less than 10% of the SNPs. There was a high degree of collinearity between the genetic and physical positions of those 335 SNP markers. The integration of 6553 SNP sites that were detected in either of the two populations with 335 common sites resulted in an extended consensus genetic map. The total length of the extended map was estimated to be 1997.9 cM, which was compatible with a previous estimate for large-fruited fresh-market tomato. A linkage panel for fresh-market tomato was also established using the combined dataset of the consensus map of 335 SNP loci and 73 SNP-genotyped core fresh-market tomatoes. An empirical genetic mapping study of the tomato brachytic trait using the linkage panel demonstrated the value of the consensus map and linkage panel for tomato research. The allelic information in the linkage panel will serve as a basis for SNP marker implementation, such as genotyping platforms and genomic association map, in tomato.