Location: Vegetable Crops Research
Project Number: 5090-21000-073-110-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 25, 2025
End Date: Aug 24, 2026
Objective:
1. Development of mapping populations (F2, F3, and/or RILs) that are segregating for downy mildew(DM) and powdery mildew (PM) resistances in two cucumber lines WI7012 and WI7855.
2. QT analysis of DM and PM resistances using these mapping populations.
3. Develop molecular markers to introgress target genes or QTL into elite pickling cucumber lines for commercial breeding.
Approach:
1. Phenotypic characterization of disease resistances in selected cucumber lines against downy mildew (DM), powdery mildew (P{M), and angular leaf spot (ALS).
2. Development of segregating populations for QTL mapping of DM, PM and ALS resistances. Disease resistant lines will be crossed with susceptible lines and develop F2 and F3 populations. Plants in these populations will be phenotyped for inoculation responses in growth chamber, greenhouse or field trials. A linkage map will be developed for each population using the DArTag SNP genotyping technology. QTL analysis will be conducted with the genotypic and phenotypic data.
3. Marker assisted germplasm enhancement. Molecular markers will be developed for major-effect resistance QTL for each disease, which will be used in marker-assisted selection or marker-assisted QTL pyramiding to introgress the target QTL into elite pickling cucumber background. The resulting germplasm will be evaluated for multiple disease resistances as well as horticulture performances before public release.