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In monoecious species, female flowering constitutes the developmental process that determines the onset and production of fruit and is therefore closely related to crop yield. This article presents the identification and phenotypic and molecular characterization of myb62, an ethylmethane sulfonate loss-of-function mutation that completely blocks the female floral transition, converting all female flowers into male flowers. BSA-seq analysis coupled with WGS showed that myb62corresponds to a C>T transition in the coding region of the gene CpMYB62, generating a premature stop codon and a truncated transcription factor without its N-terminal effector domain. The myb62phenotype was partially rescued by exogenous ethylene application, indicating that the function of CpMYB62is mediated by ethylene. Different evidence supports this conclusion: first, the reduced ethylene production of the mutant, and second, the male flower productive phenotype of the double mutant between myb62and the ethylene-insensitive mutant etr2b, which demonstrated that myb62is epistatic over etr2b. Furthermore, transcriptomic analysis of WT and myb62apical shoots confirmed that CpMYB62regulates master sex-determining genes, upregulating those encoding the ethylene biosynthesis enzymes CpACO2Band CpACS27Aand those encoding for transcription factors that promote the development of carpels(CpCRC), but downregulating those involved in the arrest of carpels (CpWIP1), In the gene network controlling sex determination in cucurbits, CpMYB62 occupies the most upstream position, activating ethylene and other sex determining genes involved in female flower determination in Cucurbitapepo.