Genome Editing for Earliness and Plant Architecture in Cucurbit Crops: Recent Advances and Future Perspectives

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.