biostudies-literatureKumar RNational Institute of Food and Agriculture299https://www.ebi.ac.uk/biostudies/studies/S-EPMC12596284biostudies-literatureUnknown138(12)<h4>Key message</h4>A major QTL conferring powdery mildew resistance was fine mapped to a 54.8 kb region on chromosome 2 using an interspecific RIL population (Citrullus mucosospermus × Citrullus lanatus). Four co-segregating KASP markers were developed and validated across multiple populations, demonstrating their utility for marker-assisted selection. Powdery mildew, caused by Podosphaera xanthii, is a major fungal disease that significantly affects watermelon production worldwide. Developing resistant cultivars through marker-assisted selection (MAS) offers an effective and sustainable strategy for disease management. In this study, a 54,772 bp quantitative trait locus (QTL) associated with powdery mildew resistance was mapped to chromosome 2 (30,111,475-30,166,247 bp) using an F₁₁ recombinant inbred line (RIL) population derived from an interspecific cross between the resistant C. mucosospermus line USVL531-MDR and the susceptible C. lanatus line USVL677-PMS. Genetic analysis revealed that resistance is controlled by a single dominant gene, supported by a 3:1 segregation ratio observed in F₂ populations. The mapped region harbored three lipoxygenase (LOX) genes and one 50S ribosomal protein L27-like gene. Four KASP markers were developed from SNPs located within four putative genes in the QTL region and were validated across multiple segregating populations, including the RIL (USVL531-MDR × USVL677-PMS) and two F₂ populations (USVL531-MDR × 'Sugar Baby' and PI 560003 × USVL677-PMS). These markers accurately differentiated resistant and susceptible individuals (R2 = 0.68-0.82) and exhibited 100% co-segregation with powdery mildew resistance in the RIL and two F₂ populations, demonstrating their utility for MAS. The identified QTL and validated KASP markers will facilitate MAS for powdery mildew resistance breeding and enable future gene cloning work.TAG. Theoretical and applied genetics. Theoretische und angewandte GenetikFine mapping, introgression, and KASP marker development for powdery mildew resistance in watermelon using an interspecific RIL population (Citrullus mucosospermus × C. lanatus).PMC125962842015-51181-242852020-51181-32139Karthikeyan RIkerd JKumar RKousik CfalseFine mapping, introgression, and KASP marker development for powdery mildew resistance in watermelon using an interspecific RIL population (Citrullus mucosospermus × C. lanatus).<h4>Key message</h4>A major QTL conferring powdery mildew resistance was fine mapped to a 54.8 kb region on chromosome 2 using an interspecific RIL population (Citrullus mucosospermus × Citrullus lanatus). Four co-segregating KASP markers were developed and validated across multiple populations, demonstrating their utility for marker-assisted selection. Powdery mildew, caused by Podosphaera xanthii, is a major fungal disease that significantly affects watermelon production worldwide. Developing resistant cultivars through marker-assisted selection (MAS) offers an effective and sustainable strategy for disease management. In this study, a 54,772 bp quantitative trait locus (QTL) associated with powdery mildew resistance was mapped to chromosome 2 (30,111,475-30,166,247 bp) using an F₁₁ recombinant inbred line (RIL) population derived from an interspecific cross between the resistant C. mucosospermus line USVL531-MDR and the susceptible C. lanatus line USVL677-PMS. Genetic analysis revealed that resistance is controlled by a single dominant gene, supported by a 3:1 segregation ratio observed in F₂ populations. The mapped region harbored three lipoxygenase (LOX) genes and one 50S ribosomal protein L27-like gene. Four KASP markers were developed from SNPs located within four putative genes in the QTL region and were validated across multiple segregating populations, including the RIL (USVL531-MDR × USVL677-PMS) and two F₂ populations (USVL531-MDR × 'Sugar Baby' and PI 560003 × USVL677-PMS). These markers accurately differentiated resistant and susceptible individuals (R2 = 0.68-0.82) and exhibited 100% co-segregation with powdery mildew resistance in the RIL and two F₂ populations, demonstrating their utility for MAS. The identified QTL and validated KASP markers will facilitate MAS for powdery mildew resistance breeding and enable future gene cloning work.2025-01-01T00:00:00Z2025 Nov2026-06-06T13:28:16.312Z2026-05-31T03:08:03.164ZS-EPMC125962844120504710.1007/s00122-025-05079-4