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United States Department of Agriculture

Agricultural Research Service

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Location: Vegetable Crops Research

2012 Annual Report

1a. Objectives (from AD-416):
1) Develop a high-resolution cucumber inter-varietal linkage map placing at least 1,200 SSRs anchored with whole genome scaffolds. 2) Develop an efficient RNAi/transformation or VIGS. 3) Develop elite lines with DM and ZYMV resistance; identify molecular markers for the recessive DM and ZYMV resistance genes that can be used for MAS in breeding. 4) Identify candidate genes for downy-mildew and ZYMV resistance, and verify their functions.

1b. Approach (from AD-416):
SSR markers were explored from cucumber whole genome sequence, and selected for mapping in an F2:3 mapping populations. Expect to place 1,200 SSRs on the map. 2. SNP discovery, SNP array development and use for fine mapping SNPs will be identified through alignment of whole genome sequences of two sequenced cucumber genotypes (9930 and Gy14), validated. SNP microarray will be manufactured through contract service to a company. The array will be used for SNP linkage mapping to identify markers linked with downy mildew and ZYMV disease resistance gene. 3. Cloning of ZYMV disease resistance locus from cucumber. Will use map-based cloning strategy.

3. Progress Report:
Development of mapping populations for quantitative trait loci (QTL) mapping of downy mildew and map-based cloning of Zucchini Yellow Mosaic Virus (ZYMV) viral resistance is underway. Parental lines and segregating populations were planted in the fields or greenhouse for phenotypic data collection. Ribonucleic acids (RNA)-Seq of the downy mildew pathogen races has been initiated. This research relates to Objective 1, Determine the genetic basis of and initiate selection for carrot, onion, cucumber, and melon quality attributes influencing human nutrition and health, disease resistances, and yield and quality components, and stress tolerance in cucurbits, and perform field performance and quality trials; Objective 2, Utilize current biotechnology to discover and evaluate genetic variation and to map agriculturally important traits in Allium, Cucurbit, and Daucus germplasm, and to develop genetic and breeding stocks.

4. Accomplishments

Last Modified: 09/22/2017
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