IMPROVEMENT OF CUCURBITS: FROM CLASSICAL BREEDING TO MODERN BIOTECHNOLOGICAL APPROACHES - STRATEGIES AND LIMITATIONS

Abstract

Cucurbits, including cucumber (Cucumis sativus), watermelon (Citrullus lanatus), melon (Cucumis melo), pumpkin, and squash (Cucurbita spp.), are among the most important horticultural crops worldwide due to their nutritional, economic, and industrial value. However, their productivity is severely constrained by numerous biotic and abiotic stresses, narrow genetic diversity resulting from domestication bottlenecks, and the complexity of breeding highly heterozygous and cross-pollinated species. This review examines the major strategies employed for cucurbit improvement, ranging from classical breeding approaches to advanced biotechnological interventions. The role of genetic resources, wild relatives, and traditional landraces in broadening the genetic base is discussed, along with the contributions of conventional breeding in developing improved cultivars with enhanced yield, quality, and disease resistance. The review further highlights the application of molecular marker-assisted selection for precise trait introgression, transgenic technologies for virus resistance, and genome editing tools such as CRISPR/Cas9 for targeted modification of agronomically important genes. In addition, the emerging potential of genomic selection for improving complex quantitative traits by utilizing genome-wide marker information is emphasized. Despite significant advances, several challenges, including limited transformation efficiency, regulatory constraints, rapid pathogen evolution, and climate change-related stresses, continue to restrict the full realization of these technologies in cucurbit breeding programs. Future improvement efforts will require the integration of genomic selection, genome editing, high-throughput phenotyping, artificial intelligence-assisted breeding, and the effective utilization of diverse genetic resources to accelerate the development of resilient, high-yielding, and climate-adapted cucurbit cultivars.