Ethylene production in melon through QTL pyramiding reveals synergistic and antagonistic interactions affecting major ripening traits

Abstract Ethylene is the key hormone controlling climacteric fruit ripening, a process that plays a crucial role in determining both fruit quality and shelf-life. Melon serves as an excellent model for studying ripening due to the presence of both climacteric and non-climacteric varieties. In this study, we fine-tuned ethylene production by combining the alleles of three non-climacteric QTLs, ETHQB3.5, ETHQV6.3, and ETHQV8.1, into a climacteric Cantaloupe background. This pyramiding strategy resulted in lines with reduced and delayed ethylene production, which in turn affected fruit flesh firmness and harvest timing. Regarding aroma, although overall volatile organic compounds (VOCs) production was reduced, the fruits retained the synthesis of specific ester-based compounds, preserving some of the characteristic sweet aroma of Cantaloupe. QTL pyramiding also revealed the impact of QTL-QTL interactions on ripening-related traits: ETHQV6.3 and ETHQV8.1 acted synergistically, while ETHQB3.5 showed an antagonistic effect on ETHQV6.3. This approach generated a range of climacteric behaviours, offering valuable genetic resources for breeding programs aimed at improving long-shelf life.