Fruit Quality MAS

A marker-assisted backcross scheme was set up for introducing favorable alleles of five major QTL regions into three tomato lines with common taste (Lecomte et al. 2004a). The results demonstrated the usefulness of such an approach for improving fruit quality. In all three genetic backgrounds, the introduced regions had a favorable effect on the traits controlled by QTLs from the cherry tomato (donor line), with the exception of fruit weight. Consumer tests revealed that the prototypes were significantly preferred over their corresponding recurrent parents. However, some of the QTL effects were specific to a single genetic background. The genetic characterization of the QTLs for organoleptic quality traits was completed by studying the stability of the QTLs (Chaib et al. 2006). This study confirmed that the QTLs were mainly specific to the

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aroma sourness sweetness aroma meltiness sweetness aroma mealiness juiciness sweetness sourness mealiness skin mealiness juiciness mealiness juiciness meltiness juiciness skin skin skin meltiness aroma meltiness sweetness sweetness

Fig. 9. QTLs detected for sensory traits in a recombinant inbred population derived from the cross between a cherry tomato and a large fruit line. Taste attributes were sweetness and sourness. Aroma attributes were overall aroma intensity, candy aroma, lemon aroma, citrus fruit (other than lemon) aroma, andpharmaceutical aroma. Texture attributes were flesh firmness, mealiness, meltiness, juiciness, and toughness of skin (adapted from Causse et al. 2001)

genetic background. Although approximately 50% of the QTLs were stable over years in the RIL population and in the genetic background used for QTL detection, a lower number of QTLs was detected in the two other genetic backgrounds.

Wild species, in spite of their unfavorable characteristics in comparison to cultivars, can carry al-leles which may contribute to the improvement of most agronomic traits (de Vicente and Tanksley 1993; Bernacchi etal. 1998a) (See Sect. 1.8). Gur and Za-mir (2004) made progress by pyramiding independent yield-promoting regions introduced from the wild species S. pennellii. Wild species may provide original aromas, either favorable to tomato quality, as found in an S. peruvianum accession (Ka-mal et al. 2001) or unfavorable as the Malodorous locus found in an S. pennellii accession (Tadmor et al. 2002).

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