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

## TL;DR

Heterozygous CmNOR/Cmnor plants in oriental melon delay ripening and extend shelf life without compromising fruit quality.

## Contribution

The study introduces a novel CmNOR dosage effect that balances fruit quality and storability in climacteric fruits.

## Key findings

- CmNOR/Cmnor heterozygotes delayed ripening by 6 days while maintaining wild-type fruit quality.
- Heterozygotes extended shelf life by 3–5 days at 20°C without quality loss.
- Transcriptomic analysis showed reduced gene expression disparities in heterozygotes compared to homozygotes.

## Abstract

Oriental melon, a climacteric fruit prized for its superior quality, faces limited shelf life. Although knockout NON-RIPENING (CmNOR) 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 Cmnor and wild-type (WT) plants, we created CmNOR/Cmnor 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 CmNOR dosage effect dynamically modulates interconnected quality and preservation networks, proposing an editing-based solution to overcome the storability-quality dichotomy in climacteric fruits.