Skip to main content
ARS Home » Southeast Area » Charleston, South Carolina » Vegetable Research » Research » Publications at this Location » Publication #380418
Research Project: Biological, Genetic and Genomic Based Disease Management for Vegetable Crops

Location: Vegetable Research

Title: QTL mapping of resistance to powdery mildew race 1 in a recombinant inbred line population of melon

Author
item BRANHAM, S - Clemson University
item Kousik, Chandrasekar - Shaker
item MANDAL, M - Claflin University
item Wechter, William - Pat

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2021
Publication Date: 12/2/2021
Citation: Branham, S.E., Kousik, C.S., Mandal, M., Wechter, W.P. 2021. QTL mapping of resistance to powdery mildew race 1 in a recombinant inbred line population of melon. Plant Disease. https://doi.org/10.1094/PDIS-12-20-2643-RE.
DOI: https://doi.org/10.1094/PDIS-12-20-2643-RE

Interpretive Summary: Powdery mildew, caused by the fungus Podosphaera xanthii, is one of the most important diseases of melon. While there are several pathogenic races of P. xanthii, race 1 is the predominant race in the U.S. We used a densely genotyped recombinant inbred line melon population for quantitative trait loci (QTL) mapping, to identify two major and two minor QTLs associated with resistance to P. xanthii race 1. QTL mapping of disease severity in multiple tissues (hypocotyl, cotyledons, true leaves and stems) identified the same genetic basis of resistance in all tissue types. Whole-genome resequencing of the parents was used for marker development across the major QTLs and functional annotation of SNPs for candidate gene analysis. Molecular markers tightly linked to the two major QTL were developed and will enable efficient marker-assisted introgression of powdery mildew resistance into improved germplasm lines. Candidate genes were identified in both major QTL intervals that encode putative resistance genes, providing genetic targets for further resistance investigations. The information on KASP markers will be useful to vegetable seed company and University Plant breeders. Information on powdery mildew resistance will be useful to seed company and University researchers and extension agents.

Technical Abstract: Powdery mildew, caused by the fungus Podosphaera xanthii, is one of the most important diseases of melon. While there are several pathogenic races of P. xanthii, race 1 is the predominant race in South Carolina and the U.S. We used a densely genotyped recombinant inbred line melon population for traditional QTL mapping, to identify two major (qPx1-5 and qPx1-12) and two minor (qPx1-4 and qPx1-10) QTLs associated with resistance to P. xanthii race 1. QTL mapping of disease severity in multiple tissues (hypocotyl, cotyledons, true leaves and stems) identified the same genetic basis of resistance in all tissue types. Whole-genome resequencing of the parents was used for marker development across the major QTLs and functional annotation of SNPs for candidate gene analysis. KASP markers were tightly linked to qPx1-5 (0 cM) and qPx1-12 (0.3 cM) in the population and will enable efficient marker-assisted introgression of powdery mildew resistance into improved germplasm lines. Candidate genes were identified in both major QTL intervals that encode putative R genes with missense mutations between the parents.