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QTL-seq and marker development for resistance to Fusarium oxysporum f. sp. niveum race 1 in cultivated watermelon

Branham, Sandra E., Patrick Wechter, W., Lambel, Shaunese, Massey, Laura, Ma, Michelle, Fauve, Julie, Farnham, Mark W., Levi, Amnon
Molecular breeding 2018 v.38 no.11 pp. 139
Fusarium oxysporum f. sp. niveum, Fusarium wilt, alleles, breeding programs, cultivars, fungi, genotyping, germplasm, polymerase chain reaction, quantitative trait loci, sequence analysis, watermelons
Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. niveum (Fon), is one of the predominant diseases of watermelon. Resistance to Fon race 1 is conferred by a single major quantitative trait locus (QTL), Fo-1.1, but resolution of this region has been poor due to low marker density. In this study, a combination of whole genome resequencing of bulked segregants (QTL-seq analysis) followed by QTL mapping with kompetitive allele specific PCR (KASP) markers developed across Fo-1.1 successfully increased the resolution from 2.03 to 1.56 Mb and 315 kb, respectively. The linkage of the KASP markers to Fon race 1 resistance across a wide range of watermelon germplasm was validated in a set of elite watermelon cultivars. The linked markers described here provide a breeder-friendly toolkit immediately available for high-throughput genotyping in large-scale breeding programs for fine mapping and incorporation of Fon race 1 resistance in watermelon.