Quantitative trait loci pyramiding for fruit quality traits in tomato

Abstract

Fruit quality is a major focus for most conventional and innovative tomato breeding strategies, with particular attention being paid to fruit antioxidant compounds. Tomatoes represent a major contribution to dietary nutrition worldwide and a reservoir of diverse antioxidant molecules. In a previous study, we identified two Solanum pennellii introgression lines (IL7-3 and IL12-4) harbouring quantitative trait loci (QTL) that increase the content of ascorbic acid (AsA), phenols and soluble solids (degrees Brix; °Bx) in tomato fruit. The purpose of the present work was to pyramid into cultivated varieties the selected QTL for enhanced antioxidant and °Bx content. To better understand the genetic architecture of each QTL, the two ILs were crossed to the recurrent parent M82 (ILH7-3 and ILH12-4) and between them (ILH7-3+12-4). F1 hybrids (ILH7-3+12-4) were then selfed up to obtain F3 progenies in order to stabilize the favourable traits at the homozygous condition. Species-specific molecular markers were identified for each introgressed region and allowed us to select four F2 genotypes carrying both introgressions at the homozygous condition. The F3 double homozygous plants displayed AsA, total phenols and °Bx content significantly higher than M82. Therefore, they may represent suitable genetic material for breeding schemes aiming to increase antioxidant content in tomato fruit.

Fig. 1

Ascorbic acid, total phenols and °Bx content in red-ripe fruit from the tomato IL7-3, IL12-4, ILH7-3, ILH12-4, ILH7-3+12-4 genotypes and the parental line M82. The mean values (±SE) are reported for at least three plant replicates grown under greenhouse conditions in 2009. Asterisks indicate statistically significant differences compared to M82 (P < 0.05)

Fig. 2

Ascorbic acid, total phenols and °Bx content in red-ripe fruit from the tomato IL7-3, IL12-4, ILH7-3, ILH12-4, ILH7-3+12-4, IL7-3+12-4 genotypes and the parental line M82. The mean values (±SE) are reported for at least seven replicates of plants field-grown in 2010. Asterisks indicate statistically significant differences compared to M82 (P < 0.05)

Fig. 3

Total plant yield (kg/plant) of IL7-3, IL12-4, ILH7-3, ILH12-4, ILH7-3+12-4, IL7-3+12-4 genotypes and the parental line M82. The mean values (±SE) are reported for at least seven plant replicates grown in the open field in 2010. Asterisks indicate statistically significant differences compared to M82 (P < 0.05), section symbol indicates statistically significant differences compared to IL7-3 (P < 0.05)