|WANG, YUHUI - University Of Wisconsin|
|VANDENLANGENBERG, KYLE - North Carolina State University|
|WEHNER, TODD - North Carolina State University|
Submitted to: Plant and Animal Genome
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2018
Publication Date: 1/13/2018
Citation: Wang, Y., Vandenlangenberg, K., Wehner, T.C., Weng, Y. 2018. Genetic architecture of downy mildew resistance in cucumber. Plant and Animal Genome XXVI Proceedings. Paper No. W269.
Technical Abstract: Downy mildew (DM) caused by the obligate oomycete Pseudoperonospora cubensis is the most devastating fungal disease to cucumber production. The molecular mechanism of DM resistance in cucumber is not well understood. We conducted QTL mapping for DM resistances in four cucumber lines including WI7120 and PI 197088 that are highly resistant to post-2004 DM strain(s) as well as Gy14 and WI2757 that offered effective protection to DM infection for over 50 years until 2004. Four QTL, dm2.1, dm4.1, dm5.2 and dm6.1 were detected for WI7120-derived resistance which together could explain 62-76% phenotypic variance; dm4.1 and dm5.2 were major-effect QTL. In PI 197088, 11 QTL were identified accounting for 73.5% total phenotypic variance, among which, three (dm5.1, dm5.2 and dm5.3) and five (dm2.1, dm3.1, dm3.2, dm4.1 and dm6.1) were major- and minor-effect contributing QTL, respectively whereas dm1.1, dm2.1, and dm6.2 conferred susceptibility. DM resistance to the post-2004 strain in Gy14 and WI2757 was controlled by one (dm1) and two (dm1, dm5.2) QTL on chromosome 5, respectively. Genome-wide association analysis identified consistent or novel DM resistance loci in natural cucumber populations. Fine genetic mapping of dm4.1, dm5.2, and dm1 further identified potential candidate genes for dm4.1, dm5.2 and dm1. The work highlighted the power of reliable phenotypic data collection, next-gen high throughout sequencing based genotyping and marker-assisted NIL development in improving the power of QTL detection. The genetic architecture of DM resistance in different resistance sources and their potential in cucumber breeding for DM resistance will be discussed.