The Control of Tomato Fruit Weight By fw2.2, fw3.2 and fw11.3 in Near Isogenic Lines in the Tomato Wild Relative Background

Fruit weight is an important trait in the domestication of horticultural vegetables. In tomato (Solanum lycopersicum L.), three major QTLs (fw2.2, fw3.2 and fw11.3) control fruit weight. The effect of each locus on fruit weight has been described but comparative studies as well as interaction effects among these three loci have never been assessed. We have used the fw2.2, fw3.2 and fw11.3 single, double and triple near isogenic lines in the wild relative tomato background (S. pimpinellifolium, LA1589). Among the three loci, fw11.3 showed the strongest effect on increasing tomato fruit weight, whereas fw2.2 has the weakest impact. In two biological replicates, no consistent interaction between any two of the three loci was found and no interaction was detected among the three loci either. To shed light on the mechanisms by which those loci increase fruit weight, fruit structure analyses were performed. Fruit pericarp area was found to be increased by all three loci, especially by fw11.3. Morphological traits of the vegetative organs were also evaluated. fw3.2 decreased the whole leaf length as well as the terminal leaf shape index, by decreasing the terminal leaf length without changing the width. In addition, terminal leaf color was also impacted by the three fruit weight loci: L* score was increased by fw2.2; Hue score was significantly increased by both fw3.2 and fw11.3; and Chroma score was reduced by fw3.2.

This project was supported by AFRI Competitive Grant no. 2013-67013-21229 from the USDA NIFA, China Agricultural University and China Scholarship Council.