Dual benefits of <i>CmNOR/Cmnor</i> heterozygous plants: prolonging shelf life and preserving fruit quality in oriental melon

Oriental melon, a climacteric fruit prized for its superior quality, faces limited shelf life. Although knockout <i>NON-RIPENING</i> (<i>CmNOR</i>) prolongs storage duration at the expense of quality loss, the potential of its direct agricultural application to reconcile this conflict remains uninvestigated. Through crossing homozygotes <i>Cmnor</i> and wild-type (WT) plants, we created <i>CmNOR/Cmnor</i> heterozygotes. These heterozygotes exhibited a 6-day ripening delay accompanied by reduced sucrose and β-carotene levels, yet ultimately attained WT quality parameters. Exogenous ethylene treatment accelerated fruit softening but failed to restore key quality parameters in both heterozygotes and homozygotes to WT levels. Transcriptomic and quantitative polymerase chain reaction (qPCR) analysis revealed that homozygotes displayed >10-fold expression differences versus WT in quality-associated genes (e.g. involved in carotenoid biosynthesis and sucrose metabolism). These expression disparities diminished to approximately 2-fold in heterozygotes. Furthermore, heterozygotes extended shelf life by 3-5 days during storage at 20°C while maintaining fruit quality. Storage-phase differential genes clustered in water regulation and cell wall modification pathways, with heterozygous-WT expression disparities gradually decreasing over time. The <i>CmNOR</i> dosage effect dynamically modulates interconnected quality and preservation networks, proposing an editing-based solution to overcome the storability-quality dichotomy in climacteric fruits.