Fine Mapping of fw6.3 , a Major-Effect Quantitative Trait Locus That Controls Fruit Weight in Tomato.

Tomato () is a widely consumed vegetable, and the tomato fruit weight is a key yield component. Many quantitative trait loci (QTLs) controlling tomato fruit weight have been identified, and six of them have been fine-mapped and cloned. Here, four loci controlling tomato fruit weight were identified in an F population through QTL seq.; ) was a major-effect QTL and its percentage of variation explanation (R) was 0.118. This QTL was fine-mapped to a 62.6 kb interval on chromosome 6. According to the annotated tomato genome (version SL4.0, annotation ITAG4.0), this interval contained seven genes, including (the gene), which was likely the candidate gene underlying variation in fruit weight. The gene contained a single-nucleotide polymorphism that resulted in an amino acid substitution in the protein sequence. The large-fruit allele of () was overdominant to the small-fruit allele . The soluble solids content was also increased by . These findings provide valuable information that will aid the cloning of the gene and ongoing efforts to breed tomato plants with higher yield and quality via molecular marker-assisted selection.