Theoretical and Applied Genetics (2014) 127, 2105-2115

Shaunese Lambel, Brenda Lanini, Elisabetta Vivoda, Julie Fauve, W. Patrick Wechter, Karen R. Harris-Shultz, Laura Massey and Amnon Levi (2014)
A major QTL associated with Fusarium oxysporum race 1 resistance identified in genetic populations derived from closely related watermelon lines using selective genotyping and genotyping-by-sequencing for SNP discovery
Theoretical and Applied Genetics 127 (10), 2105-2115
Abstract: Fusarium wilt is a major disease of watermelon caused by the soil-borne fungus Fusarium oxysporum Schlechtend.:Fr. f. sp. niveum (E.F. Sm.) W.C. Snyder and H.N. Hans (Fon). In this study, a genetic population of 168 F3 families (24 plants in each family) exhibited continuous distribution for Fon race 1 response. Using a "selective genotyping" approach, DNA was isolated from 91 F2 plants whose F3 progeny exhibited the highest resistance (30 F2 plants) versus highest susceptibility (32 F2 plants), or moderate resistance to Fon race 1 (29 F2 plants). Genotyping-by-sequencing (GBS) technology was used on these 91 selected F2 samples to produce 266 single nucleotide polymorphism (SNP) markers, representing the 11 chromosomes of watermelon. A major quantitative trait locus (QTL) associated with resistance to Fon race 1 was identified with a peak logarithm of odds (LOD) of 33.31 and 1-LOD confidence interval from 2.3 to 8.4 cM on chromosome 1 of the watermelon genetic map. This QTL was designated "Fo-1.1" and is positioned in a genomic region where several putative pathogenesis-related or putative disease-resistant gene sequences were identified. Additional independent, but minor QTLs were identified on chromosome 1 (LOD 4.16), chromosome 3 (LOD 4.36), chromosome 4 (LOD 4.52), chromosome 9 (LOD 6.8), and chromosome 10 (LOD 5.03 and 4.26). Following the identification of a major QTL for resistance using the "selective genotyping" approach, all 168 plants of the F 2 population were genotyped using the SNP nearest the peak LOD, confirming the association of this SNP marker with Fon race 1 resistance. The results in this study should be useful for further elucidating the mechanism of resistance to Fusarium wilt and in the development of molecular markers for use in breeding programs of watermelon.
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Link to article at publishers website
Database assignments for author(s): Karen Harris-Shultz

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Fusarium oxysporum f.sp. niveum	Watermelon/colocynth (Citrullus)	U.S.A. (SW)
	Fusarium oxysporum	Watermelon/colocynth (Citrullus)	U.S.A. (SW)
	Fusarium oxysporum	Watermelon/colocynth (Citrullus)	U.S.A. (SW)