ARS | Publication request: Relationship of Tomato Fruit Sugar Concentration with Physical and Chemical Traits and Linkage of Rapd Markers

Submitted to: Journal Of The American Society For Horticultural Science
Publication Acceptance Date: March 22, 2004
Publication Date: October 1, 2004
Citation: Georgelis, N., Scott, J.W., Baldwin, E.A. 2004. Relationship Of Tomato Fruit Sugar Concentration With Physical And Chemical Traits And Linkage Of Rapd Markers. Journal Of The American Society For Horticultural Science. 129(6): 839-845.

Interpretive Summary: Consumers are dissatisfied with fresh tomato flavor. Previous sensory tests have shown that the sweeter to tomato, the greater the acceptability rating. In this study a sweet small fruited variety was crossed with a less sweet large fruited variety and the progeny was analyzed with the hope of finding genetic markers that correlated with sugar and sweetness. Six genetic markers were found linked to high sugars, but five were also linked to small fruit size (this is why small fruited tomatoes like "cherry" or "grape" tomatoes are often sweeter than large tomatoes). Genetic markers can help breeders screen tomato material for specific traits like high sugar.

Technical Abstract: Small-fruited cherry tomato accession PI270248 (L. Esculentum var. cerasiforme) with high fruit sugars was crossed to large-fruited inbred line Fla. 7833-1-1-1 (7833) that had normal (low) fruit sugar. Sugars in the F2 were positively correlated with soluble solids, glucose, fructose, pH and titratable acidity, and inversely correlated with fruit size. Indeterminate plants had significantly correlated with sugars at p 0.05. Six Random Amplified Polymorphic DNA (RAPD) markers linked to high sugars were found: five dominant (OPAE4, UBC 731, UBC 744, UBC 489, UBC 290) and one co-dominant (UCB269). Five of the markers were also linked to small fruit size and one of these also was linked to low yield (UBC 290). The sixth marker (UBC 269) was linked to the indeterminate plant habit. UBC 731, UBC 489 and possible OPAE 4 were in one linkage group, while UBC 744 and UBC 290 were in another linkage group. Combinations of all the markers together explained 35% of the sugar variation in the F2 grown in spring 2002.