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Tomato is a model species for genetic analyses since a long time. Many mutations controlled by a single gene were discovered and the underlying genes were mapped first on the tomato genetic map. Most of these genes are involved in fruit colour and shape, in plant growth and architecture and in disease resistances. With the construction of high-density molecular genetic maps, many genes were located on the genome and subsequently several of them were fine-mapped and further identified by positional cloning. Today with the availability of the tomato genome sequence these genes are physically located on the genome and the identification of new ones is being considerably accelerated. The alignment of the physical and genetic maps allowed the identification of hot spots of recombination and of large regions where recombination is almost suppressed, whatever the progeny studied. The impact of this heterogeneity in recombination is discussed.

International audience; Throughout tomato domestication, a large increase in fruit size was associated with a loss of dry matter and sugar contents. This study aims to dissect the contributions of genetic variation and the physiological processes underlying the relationships between fruit growth and the accumulation of dry matter and sugars. Fruit quality traits and physiological parameters were measured on 20 introgression lines derived from the introgression of Solanum chmielewskii into S. lycopersicum, under high (HL, unpruned trusses) and low (LL, trusses pruned to one fruit) fruit load conditions. Inter- and intra-genotypic correlations among traits were estimated and quantitative trait loci (QTL) for size, composition, and physiological traits were mapped. LL increased almost all traits, but the response of sugar content was genotype-dependent, involving either dilution effects or differences in carbon allocation to sugars. Genotype3fruit load interactions were significant for most traits and only 30% of the QTL were stable under both fruit loads. Many QTL for fresh weight and cell or seed numbers co-localized. Eleven clusters of QTL for fresh weight and dry matter or sugar content were detected, eight with opposite allele effects and three with negative effects. Two genotypic antagonistic relationships, between fresh weight and dry matter content and between cell number and cell size, were significant only under HL; the second could be interpreted as a competition for carbohydrates among cells. The role of cuticular conductance, fruit transpiration or cracking in the relationship between fruit fresh weight and composition was also emphasized at the genetic and physiological levels.