Tomato fruit quality traits and metabolite content are affected by reciprocal crosses and heterosis

Heterosis occurs when the F1 individuals exhibit increased performance for
a number of traits compared to their parental lines. On the other hand,
reciprocal hybrids are obtained by changing the cross direction (or the
sexual role) of parental genotypes in a cross. Both biological phenomena
could affect the external and internal attributes of fleshy fruits. This
work aimed to detect reciprocal effects and heterosis in different tomato
(Solanum lycopersicum) for fruit quality traits and metabolite content.
Twelve agronomic fruit traits and 28 metabolites identified and estimated
by 1H NMR were evaluated in five cultivars grown in two environments. Due
to the genotype component was the most important over the phenotype, the
traits were evaluated following a full diallel mating design among those
cultivars, in greenhouse. Data demonstrated that hybrids performed a
higher phenotypic diversity than parental lines. Although both type of
traits displayed reciprocal effect and heterosis, the metabolites had a
bigger impact on generating this variation, mainly the amino acids. This
coincided with the fact that agronomic traits were more influenced by GCA
and metabolites by SCA. Furthermore, a relationship between genetic
distance between parental lines and reciprocal effect or heterosis was not
found. Hybrids with heterosis and high content of metabolites related to
tomato flavour and nutritional components were obtained. Results of this
work highlight the impact of selecting the role of 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.