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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #344775
Title: QTL mapping of downy and powdery mildew resistances in PI 197088 cucumber with genotyping-by-sequencing in RIL population

Author
item WANG, YUHUI - University Of Wisconsin
item VANDENLANGENBERG, KYLE - North Carolina State University
item WEN, CHANGLONG - Beijing Academy Of Agricultural Sciences
item WEHNER, TODD - North Carolina State University
item Weng, Yiqun

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2017
Publication Date: 11/20/2017
Citation: Wang, Y., Vandenlangenberg, K., Wen, C., Wehner, T.C., Weng, Y. 2017. QTL mapping of downy and powdery mildew resistances in PI 197088 cucumber with genotyping-by-sequencing in RIL population. Theoretical and Applied Genetics. 131(3):597-611. https://doi.org/10.1007/s00122-017-3022-1.
DOI: https://doi.org/10.1007/s00122-017-3022-1

Interpretive Summary: The downy mildew (DM) and powdery mildew (PM) are the two most important foliar diseases of cucurbit crops worldwide. The cucumber accession PI 197088 exhibits high level resistances to both pathogens. Here we reported QTL mapping results for DM and PM resistances with 148 recombinant inbred lines from a cross between PI 197088 and the susceptible line ‘Coolgreen’. Phenotypic data on responses to natural DM and PM infection were collected in multi-year and multi-location replicated field trials. A high-density genetic map with 2,780 single nucleotide polymorphisms (SNPs) from genotyping-by-sequencing and 55 microsatellite markers was developed, which revealed genomic regions with segregation distortion and mis-assemblies in the ‘9930’ cucumber draft genome. QTL analysis identified 11 and 4 QTL for DM and PM resistances accounting for more than 73.5% and 63.0% total phenotypic variance, respectively. Among the 11 DM resistance QTL, dm5.1, dm5.2 and dm5.3 were major-effect contributing QTL whereas dm1.1, dm2.1, and dm6.2 conferred susceptibility. Of the 4 QTL for PM resistance, pm5.1 was the major-effect QTL explaining 32.4% phenotypic variance and the minor-effect QTL pm6.1 contributed to disease susceptibility. Three PM QTL, pm2.1, pm5.1 and pm6.1 were co-localized with DM QTL dm2.1, dm5.2, and dm6.1, respectively, which was consistent with the observed linkage of PM and DM resistances in PI 197088. The genetic architecture of DM resistance in PI 197088 and another resistant line WI7120 (PI 330628) was compared, and the potential of using PI 197088 in cucumber breeding for downy and powdery mildew resistances is discussed.

Technical Abstract: The downy mildew (DM) and powdery mildew (PM) are the two most important foliar diseases of cucurbit crops worldwide. The cucumber accession PI 197088 exhibits high level resistances to both pathogens. We conducted QTL mapping to identified genes underlying host resistance for DM and PM in PI 197088 using 148 recombinant inbred lines from a cross between PI 197088 and the susceptible line ‘Coolgreen’. Phenotypic data on responses to natural DM and PM infection were collected in multi-year and multi-location replicated field trials. A high-density genetic map with 2,780 markers was developed. This map revealed genomic regions with segregation distortion and mis-assemblies in the ‘9930’ cucumber draft genome. QTL analysis identified 11 and 4 QTL for DM and PM resistances accounting for more than 73.5% and 63.0% total phenotypic variance, respectively. Among the 11 DM resistance QTL, three in chromosome 5 were major-effect contributing QTL whereas three conferred susceptibility. Four 4 QTL for PM resistance were identified with the one on chromosome 5 being the major-effect QTL explaining 32.4% phenotypic variance. Three PM-DM QTL pairs were co-localized, which explained the observed linkage of PM and DM resistances in PI 197088. The genetic architecture of DM resistance in PI 197088 and another resistant line WI7120 (PI 330628) was compared, and the potential of using PI 197088 in cucumber breeding for downy and powdery mildew resistances is discussed.