Heterosis occurs when the F₁s outperform their parental lines for a trait. Reciprocal hybrids are obtained by changing the cross direction of parental genotypes. Both biological phenomena could affect the external and internal attributes of fleshy fruits. This work aimed to detect reciprocal effects and heterosis in tomato (Solanum lycopersicum) fruit quality traits and metabolite content. Twelve agronomic traits and 28 metabolites identified and estimated by ¹H-NMR were evaluated in five cultivars grown in two environments. Given that the genotype component was more important than the phenotype, the traits were evaluated following a full diallel mating design among those cultivars, in a greenhouse. Hybrids showed a higher phenotypic diversity than parental lines. Interestingly, the metabolites, mainly amino acids, displayed more reciprocal effects and heterosis. Agronomic traits were more influenced by general combining ability (GCA) and metabolites by specific combining ability (SCA). Furthermore, the genetic distance between parental lines was not causally related to the occurrence of reciprocal effects or heterosis. Hybrids with heterosis and a high content of metabolites linked to tomato flavour and nutritious components were obtained. Our results highlight the impact of selecting a cultivar as male or female in a cross to enhance the variability of fruit attributes through hybrids as well as the possibility to exploit heterosis for fruit composition.

Fruit weight (FW) and shelf life (SL) are important traits in commercial fresh market tomatoes. A tomato RIL population was developed by antagonistic and divergent selection for both traits from an interspecific cross between the Solanum lycopersicum L. cv. “Caimanta” and the S. pimpinellifolium L. accession “LA0722”. The objective of this work was to evaluate phenotypic and genetic components for FW and SL. Phenotypic data from RILs were collected during 3-year trials. Sixteen SSR, 62 InDels developed based on the genome sequences of “Caimanta” and “LA0722”, and four functional markers for fruit size genes were used. FW and SL had a significant genetic variability, and both traits showed a genotype by year interaction. Genome-wide molecular characterization of the population demonstrated that is genetically structured according to FW. Marker data was used to study changes on allelic frequencies at loci between the phenotypic extreme group of RILs for FW and SL. Twenty four markers were associated to FW, the LC gene in chromosome 2 and other six markers in chromosomes 1, 2, 6, and 11 presented the most significant associations. Finally, we reported three new genomic regions located on chromosomes 9, 10 and 12 that underlie SL in tomato.

The aim of this study was to detect polypeptides and genomic regions associated with fruit quality traits in a backcross generation using as parent the Argentinean cultivated tomato Caimanta of Solanum lycopersicum and the wild accession LA722 of S. pimpinellifolium. We tested two types of molecular marker: polypeptide profile (at two ripening stages, mature green and red ripe) and SRAP (sequence-related amplified polymorphism). A polypeptide of 45 kDa present in the wild parents at the mature green stage was associated with larger fruit and long shelf life. Some amplification fragments from SRAP markers were associated with more than one quality trait such as fruit color, firmness, titratable acidity, and fruit soluble solids content. This study demonstrated for the first time the usefulness of the polypeptide profiles of pericarp and SRAP markers in finding associations with quality fruit traits in a tomato backcross generation.