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ARS Home » Southeast Area » Charleston, South Carolina » Vegetable Research » Research » Publications at this Location » Publication #377718

Research Project: Biological, Genetic and Genomic Based Disease Management for Vegetable Crops

Location: Vegetable Research

Title: QTL mapping of resistance to Pseudoperonospora cubensis clade 1, mating type2, in Cucumis melo

Author
item TOPOREK, S - CLEMSON UNIVERSITY
item BRANHAM, S - CLEMSON UNIVERSITY
item Katawczik, Melanie
item KEINATH, A - CLEMSON UNIVERSITY
item Wechter, William - Pat

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cucurbit downy mildew (CDM), is one of the largest threats to cucurbit production in the eastern United States. Currently, no melon cultivars have significant levels of resistance. Additionally, little is understood about the genetic basis of resistance in melon. Recombinant inbred lines (RILs) generated from a cross between the resistant melon breeding line MR-1 and susceptible cultivar Ananas Yok’neam (AY) were screened for CDM resistance in both greenhouse and growth chamber studies. Molecular markers called quantitative trait loci (QTL) were identified that were linked to resistance using the RIL population. Nine QTL, including two major QTL, were associated with CDM resistance. Of the major QTL, qPcub-10.1 was stable across growth chamber and greenhouse tests, whereas qPcub-8.2 was detected only in growth chamber tests. qPcub-10.1 co-located with an MLO-like protein coding gene, which has been shown to confer resistance to powdery mildew and Phytophthora disease in other plants. This is the first screening of the melon germplasm with a genetically characterized downy mildew isolate. This information will be extremely important for melon breeders and seed company personnel for the incorporation of CDM resistance into elite cantaloupe and honeydew lines using a marker assisted breeding approach. The resulting cultivars will address a serious need by growers for CDM resistance in melon.

Technical Abstract: Pseudoperonsopora cubensis, causal organism of cucurbit downy mildew (CDM), is one of the largest threats to cucurbit production in the eastern United States. Currently, no Cucumis melo (melon) cultivars have significant levels of resistance. Additionally, little is understood about the genetic basis of resistance in C. melo. Recombinant inbred lines (RILs; N=169) generated from a cross between the resistant melon breeding line MR-1 and susceptible cultivar Ananas Yok’neam (AY) were phenotyped for CDM resistance in both greenhouse and growth chamber studies. A high-density genetic linkage map with 5,663 binned SNPs created from the RIL population was utilized for QTL mapping. Nine QTL, including two major QTL, were associated with CDM resistance. Of the major QTL, qPcub-10.1 was stable across growth chamber and greenhouse tests, whereas qPcub-8.2 was detected only in growth chamber tests. qPcub-10.1 co-located with an MLO-like protein coding gene, which has been shown to confer resistance to powdery mildew and Phytophthora in other plants. This is the first screening of C. melo germplasm with a genetically characterized P. cubensis isolate.