Fruit and vegetable crops are rich in dietary fibre, vitamins and minerals, which are vital to human health. However, many biotic stressors (such as pests and diseases) and abiotic stressors threaten crop growth, quality, and yield. Traditional breeding strategies for improving crop traits include a series of backcrosses and selection to introduce beneficial traits into fine germplasm, this process is slow and resource-intensive. The new breeding technique known as clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein-9 (Cas9) has the potential to improve many traits rapidly and accurately, such as yield, quality, disease resistance, abiotic stress tolerance, and nutritional aspects in crops. Because of its simple operation and high mutation efficiency, this system has been applied to obtain new germplasm resources via gene-directed mutation. With the availability of whole-genome sequencing data, and information about gene function for important traits, CRISPR-Cas9 editing to precisely mutate key genes can rapidly generate new germplasm resources for the improvement of important agronomic traits. In this review, we explore this technology and its application in fruit and vegetable crops. We address the challenges, existing variants and the associated regulatory framework, and consider future applications.

Rapeseed (Brassica napus L.) is an important oil crop worldwide, and effective weed control can protect its yield and quality. Farmers can benefit from cultivars tolerant to herbicides such as glyphosate. Amino acid substitutions in enolpyruvylshikimate-3-phosphate synthase (EPSPS) render the plant less sensitive to glyphosate. Therefore, we aimed to optimize the glyphosate tolerance trait in rapeseed via endogenous EPSPS modification. To achieve effective gene replacement in B. napus L., we employed a CRISPR/Cas9 system expressing single-guide RNAs (sgRNAs) cleaved by the CRISPR-associated RNA endoribonuclease Csy4 from Pseudomonas aeruginosa, for targeted induction of double-strand breaks. Both the donor template and a geminiviral replicon harbouring an sgRNA expression cassette were introduced into plant cells. Using sgRNAs targeting adjacent donor DNA template containing synonymous mutations in sgRNA sites, we achieved precise gene replacements in the endogenous B. napus EPSPS gene, BnaC04EPSPS, resulting in amino acid substitutions at frequencies up to 20%. Rapeseed seedlings harbouring these substitutions were glyphosate-tolerant. Furthermore, modifications in BnaC04EPSPS were precisely transmitted to the next generation. Our genome editing strategy enables highly efficient gene targeting and the induction of glyphosate tolerance in oilseed rape.

Melon (Cucumis melo L.) is a protected crop in China with high economic value. Agrobacterium-mediated genetic transformation is a powerful tool to improve agronomic traits and obtain elite germplasm. However, current transformation protocols in melons are inefficient and highly genotype-dependent. To improve transformation in melon, we tested different infiltration methods for Agrobacterium-mediated transformation. Among these methods, micro-brushing and sonication for 20 s, followed by vacuum infiltration at −1.0 kPa for 90 s, resulted in the strongest green fluorescent protein signal and increased the proportion of infected explants. We transformed melon with developmental regulatory genes AtGRF5, AtPLT5, AtBBM, AtWUS, AtWOX5, and AtWIND1 from Arabidopsis and estimated regeneration frequencies as the number of regenerating shoots/total number of inoculated explants in the selection medium. The overexpression of AtGRF5 and AtPLT5 in melon resulted in transformation efficiencies of 42.3% and 33% in ZHF and 45.6% and 32.9% in Z12, respectively, which were significantly higher than those of the control. AtGRF5 and AtPLT5 expression cassettes were added to CRISPR/Cas9 genome-editing vectors to obtain transgenic phytoene desaturase CmPDS knockout mutants. Using AtGRF5 or AtPLT5, multi-allelic mutations were observed at CmPDS target sites in recalcitrant melon genotypes. This strategy enables genotype-flexible transformation and promotes precise genome modification technologies in melons.

Earliness and plant architecture are major breeding targets in cucurbit crops because they influence crop duration, early yield, planting density, canopy management, and production efficiency. This review summarizes genetic, molecular, and genome-editing advances related to flowering, sex expression, fruit development, stem elongation, branching, and canopy architecture in cucumber, melon, watermelon, Cucurbita species, and other cucurbits. Current evidence shows that earlier flowering or increased femaleness does not necessarily lead to earlier commercial maturity, while compact growth must be evaluated together with yield, fruit quality, and environmental adaptation. CRISPR/Cas9 knockout remains the most established editing approach, whereas base editing, cis-regulatory editing, multiplex editing, developmental-regulator-assisted regeneration, and DNA-free RNP delivery offer promising routes toward more precise trait optimization. Major constraints include genotype-dependent transformation, pleiotropic effects, limited validation in elite germplasm, and scarce direct evidence for shortening fruit-development duration. An evidence-guided framework is proposed that links trait definition, functional genomics, target prioritization, tailored genome editing, whole-plant evaluation, and breeding deployment. Future progress will depend on quantitatively tuned alleles and coordinated optimization of reproductive timing, canopy architecture, productivity, fruit quality, and environmental stability.

Earliness and plant architecture are major breeding targets in cucurbit crops because they influence crop duration, early yield, planting density, canopy management, and production efficiency. This review summarizes genetic, molecular, and genome-editing advances related to flowering, sex expression, fruit development, stem elongation, branching, and canopy architecture in cucumber, melon, watermelon, Cucurbita species, and other cucurbits. Current evidence shows that earlier flowering or increased femaleness does not necessarily lead to earlier commercial maturity, while compact growth must be evaluated together with yield, fruit quality, and environmental adaptation. CRISPR/Cas9 knockout remains the most established editing approach, whereas base editing, cis-regulatory editing, multiplex editing, developmental-regulator-assisted regeneration, and DNA-free RNP delivery offer promising routes toward more precise trait optimization. Major constraints include genotype-dependent transformation, pleiotropic effects, limited validation in elite germplasm, and scarce direct evidence for shortening fruit-development duration. An evidence-guided framework is proposed that links trait definition, functional genomics, target prioritization, tailored genome editing, whole-plant evaluation, and breeding deployment. Future progress will depend on quantitatively tuned alleles and coordinated optimization of reproductive timing, canopy architecture, productivity, fruit quality, and environmental stability.