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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Research Project #430949

Research Project: CucCAP: Leveraging Applied Genomics for Improvement of Disease Resistance and Fruit Quality of Cucurbit Crops

Location: Vegetable Crops Research

Project Number: 5090-21000-069-12-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2015
End Date: Aug 31, 2019

Objective:
The Cucurbitaceae family includes many high-value, flavorful, and nutritious crops consumed as vegetables and fruits in the American diet. U.S. production of watermelons, melons, cucumbers, squash, and pumpkins contributed an average of $1.65 billion farm gate value per year during the previous five years (2009-2013; USDA-NASS). The objective of this proposed project is to develop genomic tools useful for enhancing disease resistance in cucurbit crops and in the long run enable growers to have superior varieties that deliver high yield, excellent fruit quality, and protection against major diseases. 1. Fine genetic mapping of downy mildew major-effect QTL 2. Genome-wide association study for disease resistance genes 3. Gene pyramiding to develop enhanced germplasm for downy mildew, powdery mildew and ZYMV resistances

Approach:
In this proposed project we will combine research efforts with ARS and University Scientists at Cornell, Michigan State University, North Carolina State University, Wisconsin, and University of Georgia, Athens to use genetic populations and advanced genomic technologies to identify quantitative trait loci (QTL) associated with disease resistance. Objective 1: 1)Development of near isogenic lines (NILs) for dm4.1 and dm5.1 major-effect QTL with marker-assisted selection and field/growth chamber screening 2) Develop segregating populations (F2/F2:3) for each NIL 3) Conduct genotyping-by-sequencing and SNP-genotyping of segregating populations to narrow down QTL regions 4) Bioinformatic analysis of target regions for candidate genes 5) Structural and functional characterization of candidate genes for DM QTLs Objective 2: 1) Seed increase of 1,000 cucumber lines 2) Phenotyping 300 cucumber lines in field and greenhouse focusing of DM resistance and morphological traits 3) Genotyping of 300 cucumber lines with GBS 4) Association analysis Objective 3: 1) Develop base populations for pyramiding of resistances for DM (major-effect QTL), PM (major-effect QTL) and ZYMV in Gy14 pickling cucumber genetic background 2) Development and optimize SNP-based high throughput genotyping 3) Marker-assisted selection of plants carrying PM and ZYMV resistance alleles 4) Make cross to bring DM major-effect QTLs; backcross and self, select plants with ideal combinations 5) Conduct field and greenhouse screening tests to verify marker data