Fruit yield depends both on the flowering of the plant and on its capacity to sustain fruit development until the ripe stage. In addition, it relies on the interaction between genetic factors and environmental inputs. Uncovering the genetic basis of this complex quantitative trait was mainly investigated using natural variability in tomato, with particular outcomes due to the merging of genomes, such as heterosis, or to genetic background effects on yield evaluation. Here, we proposed to search for novel alleles regulating tomato fruit yield using Micro-Tom EMS mutants. Evaluation of total yield over several generations allowed us the selection of two tomato mutants presenting a steady increase of fruit yield from 13 to 27 %. Phenotyping of yield trait components in F2 segregant populations associated to a mapping-by-sequencing strategy (Garcia et al., 2016), combined with KASPAR genotyping and bulk segregant analysis, was undertaken in order to identify causal mutations in both mutants. Our first results suggest that the high yield observed in both mutants results from a combination of 1 to 4 loci with positive or negative effects on fruit yield components. Major alleles are currently under investigation by CRISPR-Cas9 mutagenesis and by studying the effect of allelic combination interactions on yield. In parallel, the relevance of the high-yield alleles for breeding strategies is evaluated by transfer into different tomato cultivars. Garcia V et al. Rapid identification of causal mutations in tomato EMS populations via mapping-by-sequencing. Nat Protoc. 2016 11(12):2401-2418. doi: 10.1038/nprot.2016.143