Genetic analysis of organoleptic quality in fresh market tomato. 2. Mapping QTLs for sensory attributes

The organoleptic quality of fresh market tomato can be described by a set of attributes, including fruit appearance, taste, aroma and texture. Sensory analysis is the most-valid method to study organoleptic characteristics, particularly aroma and texture. A range of 144 recombinant inbred lines of tomato derived from a cross between a cherry tomato line and a large-fruited line was evaluated by descriptive sensory profiling. Taste was analyzed through sweetness and sourness, and aroma was analyzed through the overall aroma intensity, together with candy, lemon, citrus-fruit and pharmaceutical aroma. Texture was characterized by firmness, meltiness, mealiness, juiciness and difficulty to swallow the skin. A wide range of overall variation was shown for all the attributes and significant differences among genotypes were detected. The overall aroma intensity was positively correlated with sweetness and sourness, as well as with lemon, candy and citrus fruit aromas. It was negatively correlated with mealiness. Sweetness and sourness were negatively correlated together. Molecular markers were used to map quantitative trait loci (QTLs) for each sensory attribute. One to five QTLs were detected, by simple and composite interval mapping, per attribute. The percentage of phenotypic variation explained ranged from 9% to 45% per QTL. Clusters of QTLs were observed on chromosomes 2 and 9, involving QTLs for aroma, taste and texture attributes. Most of the favorable alleles came from the cherry tomato parent, showing the potential usefulness of this line for tomato organoleptic quality improvement.