Fruit ripening is an essential process in plant development as it allows seed dispersion at the end of the fruit development. It is also a crucial factor in fruit shelf life, making fruit ripening behavior one of the main goals in plant breeding. Ethylene is a hormone that plays a key role in fruit ripening, and together with the respiration pattern determines whether the fruit ripens as climacteric or non‐climacteric. In melon (Cucumis melo) there are both climacteric and non‐climacteric varieties, making it an ideal crop to study fruit ripening from a genomics point of view. By QTL mapping in a Recombinant Inbred Line population funded by the climacteric variety ‘Védrantais’ and the non‐climacteric ‘Piel de Sapo’, we identified a major QTL in chromosome 8: ETHQV8.1, covering a region of 140 kb. ETHQV8.1 was validated and fine‐mapped using Introgression Lines (ILs) funded by the same parental lines and F2 populations, narrowing down the interval to a region of 5.8 Kb containing a single gene: MELO3C024520.2. Annotated as Ethylene Responsive Transcription Factor 024 or ERF024, its expression was correlated with climacteric ripening behavior. In ‘Védrantais’, it had a peak of expression at 30 days after pollination (DAP), at the beginning of climacteric ripening, while in ‘Piel de Sapo’ it was barely expressed. We also observed an effect in the ILs, correlated with their ripening behavior. To validate ERF024 as the causal gene of ETHQV8.1, gene editing using CRISPR/Cas9 technique was performed. Two knock‐out lines with nonsense mutations were obtained, and a preliminary phenotyping experiment suggested ERF024 as the causal gene. In order to investigate the gene function, a DAP‐seq experiment was performed to find the genes regulated by ERF024, together with a gene co‐expression analysis based on RNA‐seq data. A list of 26 genes were found being co‐expressed with ERF024 and having a binding peak in their promoter, considering them High Confident Targets (HCT). A Gene Ontology analysis of these HCTs revealed a significant enrichment in DNA structure‐related terms, suggesting an important role of ERF024 in the control of DNA structural changes associated with the transcriptomic switch happening during climacteric fruit ripening in melon.

Resumen del trabajo presentado en Cucurbitaceae 2022, congreso celebrado en Naples, Florida (Estados Unidos) del 30 de octubre al 2 de noviembre de 2022.

Peer reviewed