Cucurbits (Cucurbitaceae) include major horticultural crops with high nutritional and economic value that also serve as model plants for studying plant development and crop improvement. Conventional breeding methods have made important contributions to the production of cucurbit crops but have led to a breeding bottleneck because of the narrow genetic bases and low variation rates of these crops. With the development of molecular techniques, innovations in germplasm development through transgenesis and gene editing have led to breakthroughs in horticultural crop breeding. Although the development of genetic transformation and gene editing techniques for cucurbit crops has lagged behind that for other major crops, great progress has been made in recent years. Here, we summarize recent advances in improving the genetic transformation efficiency of cucurbit crops, including the screening of germplasm and the application of physical treatments, morphogenic genes, and selection markers. In addition, we review the application of gene editing technology to cucurbit crops, including CRISPR (clustered regularly interspaced short palindromic repeat)/Cas9 (CRISPR-associated nuclease 9)-mediated gene knockout and base editing. This work provides a reference for improving genetic transformation efficiency and gene editing technology for cucurbit crops.

Melon (Cucumis melo L.) is a globally important fruit crop, but progress in molecular breeding has been hampered by limited functional dissection of genes associated with agronomic traits. Therefore, we developed a comprehensive genome resource based on the C. melo ssp. agrestis accession 13C. This resource includes a complete telomere-to-telomere genome assembly, including accurate quantification of 45S rDNA copy number in melon, a transcriptome atlas from 31 tissue samples, a phenotypically diverse EMS-induced mutant library and a stable transformation system. By sequencing 1,125 M2 families, we identified about 660,000 variants, which cover 97.33% of the annotated gene space. Leveraging these integrated resources, we identified and functionally characterized several key genes, including CLAVATA3 INSENSITIVE RECEPTOR KINASES 2 (CmCIK2), which regulates carpel number; PARA-AMINOBENZOIC ACID SYNTHASE (CmACDS), a central regulator of folate biosynthesis; and a mutant allele of the known gynoecious gene WIP DOMAIN PROTEIN 1 (CmWIP1). In addition, we discovered a specific EMS-induced variant in the fruit ripening regulator CmNAC-NOR, and further validated its function by generating targeted mutants. The CmNAC-NOR mutants exhibited delayed fruit ripening, thus providing a valuable resource for improving ripening traits in agrestis accessions. To facilitate broader utilization, we developed the Melon Information Resource, available at https://zhanglab.qau.edu.cn/melon/index.php, an integrated platform housing 13C comprehensive genome resources and associated convenient analysis tools. This unified and accession-specific resource offers unprecedented opportunities to accelerate gene discovery and trait improvement in melon through functional genomics and molecular breeding.