Superior fruit total soluble solid content of red x pink F1 hybrids over nearly-isogenic parental lines

Abstract

Pink-coloured tomatoes are reputed as good flavoured and are very popular in local markets. Pink tomatoes show a transparent, colourless fruit cuticle in contrast to the naringenin-chalcone flavonoid-rich, orange-yellow cuticle of normal, red tomatoes due to the y (colourless epidermis) recessive mutation in MYB12 gene located in chromosome 1. In order to investigate the basis of the alleged higher quality of pink vs. red tomatoes and, especially, our previous observations of good flavour in hybrids between red and pink tomato varieties, two red x pink F1 crosses between pairs of tomato near-isogenic lines were obtained, namely ‘Ailsa Craig’ wt/wt x ‘Ailsa Craig’ y/y and ‘Ponderosa Red’ wt/wt x ‘Ponderosa Red’ y/y, being the latter a pink tomato line in which y allele was introgressed from its closely related ‘Ponderosa Pink’ cultivar. The parental lines and the two F1 hybrids were grown to harvest in a greenhouse and total soluble solids (°Brix) and titratable acidity (TA) were measured in red ripe fruits. While no differences for °Brix were observed between the parents of each cross, significantly higher °Brix was measured in the two red x pink F1’s compared to their corresponding parental lines. No clear differences between parental lines and F1 crosses were shown for TA. The experiment was repeated but including also the pink x red, reciprocal F1 crosses. The overdominance for °Brix but not for TA was confirmed in the red x pink hybrids while the pink x red hybrids produced °Brix values similar to those of their parents.