Simranjot Kaur, Shallu Thakur, P. S. Sabharwal, Geoffrey Meru
Cucumber (Cucumis sativus L.) is a globally important crop valued for both fresh consumption and processing, particularly in the United States. It was the first specialty crop among horticultural crops with a publicly available draft genome, providing a foundation for molecular breeding and trait discovery. However, cucumber production faces significant yield losses due to a wide range of biotic stresses. The crop is highly susceptible to fungal, viral, and bacterial pathogens throughout its lifecycle. To combat these challenges, breeders deploy conventional and contemporary breeding strategies to develop disease-resistant cultivars. Advances in high-throughput sequencing and genomic tools, such as quantitative trait loci mapping, genome-wide association studies, and genomic selection, have accelerated the identification and subsequent integration of resistance genes and loci into elite cucumber germplasm. This review highlights recent progress in resistance breeding for biotic stress management in cucumber, with a focus on major diseases caused by fungal, viral, and bacterial pathogens. It emphasizes the role of genomic tools, the discovery of key resistance genes and QTLs, and the potential of modern breeding approaches to improve crop resilience. Continued innovation and integration of emerging technologies will be essential for developing durable, broad-spectrum resistance in future cucumber cultivars.