regulates tomato fruit size through the floral meristem development network.

A dramatic evolution of fruit size has accompanied the domestication and improvement of fruit-bearing crop species. In tomato (), naturally occurring cis-regulatory mutations in the genes of the CLAVATA-WUSCHEL signaling pathway have led to a significant increase in fruit size generating enlarged meristems that lead to flowers with extra organs and bigger fruits. In this work, by combining mapping-by-sequencing and CRISPR/Cas9 genome editing methods, we isolated (), an AP2/ERF transcription factor which regulates floral meristem activity. Thus, the gene mutation gives rise to plants that yield larger multilocular fruits due to an increased size of the floral meristem. Genetic analyses indicate that exhibits synergistic effects with mutations at the (encoding ) and (encoding ) loci, two central players in the evolution of fruit size in the domestication of cultivated tomatoes. Our findings reveal that an mutation causes a substantial expansion of expression domains in a flower-specific manner. In vitro binding results show that ENO is able to interact with the GGC-box cis-regulatory element within the promoter region, suggesting that ENO directly regulates expression domains to maintain floral stem-cell homeostasis. Furthermore, the study of natural allelic variation of the locus proved that a cis-regulatory mutation in the promoter of had been targeted by positive selection during the domestication process, setting up the background for significant increases in fruit locule number and fruit size in modern tomatoes.