Research Article

fw2.2: A Quantitative Trait Locus Key to the Evolution of Tomato Fruit Size

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Science  07 Jul 2000:
Vol. 289, Issue 5476, pp. 85-88
DOI: 10.1126/science.289.5476.85

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Domestication of many plants has correlated with dramatic increases in fruit size. In tomato, one quantitative trait locus (QTL), fw2.2, was responsible for a large step in this process. When transformed into large-fruited cultivars, a cosmid derived from the fw2.2 region of a small-fruited wild species reduced fruit size by the predicted amount and had the gene action expected for fw2.2. The cause of the QTL effect is a single gene, ORFX, that is expressed early in floral development, controls carpel cell number, and has a sequence suggesting structural similarity to the human oncogene c-H-ras p21. Alterations in fruit size, imparted byfw2.2 alleles, are most likely due to changes in regulation rather than in the sequence and structure of the encoded protein.

  • * These authors contributed equally to this work.

  • Present address: Department of Biological Sciences, Clapp Laboratory, Mount Holyoke College, South Hadley, MA 01075, USA.

  • Present address: Research Institute for Vegetable and Ornamental Plant Breeding, IMOF-CNR, Via Universita 133, 80055 Portici, Italy.

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