Recent Progress in Genetic Transformation and Gene Editing Technology in Cucurbit Crops

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.