2009 Annual Report
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.
Sub-objective 2.A. Construct genetic maps of nuclear and organellar genomes using candidate genes, SCARs, SSRs, SNPs, transposon insertions, BACs, and cytogenetic stocks.
Sub-objective 2.B. Fine map pigment and carbohydrate genes in carrot and onion, resistance genes for nematode in carrot and viruses in cucurbits, and epistasis, yield and quality components in cucumber.
Sub-objective 2.C. Perform marker-assisted selection of carrot nematode resistance, onion male sterility, and cucurbit yield and quality.
Sub-objective 2.D. Evaluate transgene escape in cucurbits.
Sub-objective 2.E. Determine transposon mobility in carrot.
Discovery Goal 1 - Identify unique phenotypic variation in germplasm collections and breeding stocks to improve nutritional and processing quality, disease resistance, stress tolerance, and yield of Allium, Cucurbit, and Daucus vegetables, genetically characterize observed variation and initiate genetic incorporation of these phenotypes into elite germplasms.
Many biotechnological tools have been developed to improve the efficiency of crop improvement. Objective 2 evaluates and develops these tools of carrot, onion, cucumber, and melon improvement. Identify adequate DNA polymorphisms in elite onion, cucumber, melon, and carrot germplasm to construct genetic maps for marker-facilitated selection of major horticultural traits.
Discovery Goal 2.A – Identify adequate DNA polymorphisms in elite onion, cucumber, melon, and carrot germplasm to construct genetic maps for marker-facilitated selection of major horticultural traits.
Discovery Goal 2.B – Evaluate variation at candidate genes in pigment and carbohydrate biochemical pathways for mapping in onion, cucurbit, and carrot.
Discovery Goal 2.C – Identify and utilize markers to accurately identify desirable genotypes for male sterility restoration in onion, cucurbit yield, and carrot nematode resistance.
Discovery Goal 2.D – Appraise the potential benefit(s) that transgenes might confer on transgenic populations using the ELISA test to estimate the degree of viral infection in wild populations and to determine the potential risk of virus gene introgression from commercial transgenic cultivation.
Discovery Goal 2.E - Determine if native transposable elements in the carrot genome, such as DcMaster, and introduced ones, such as maize elements Ac and Ds transpose to new chromosomal regions.
Onion families segregating for health-enhancing fructans demonstrated that two major chromosome regions control the accumulation of health-enhancing fructans. Low-pungency onions possess recessive alleles at these two regions, reducing the ability of these onions to accumulate fructans. Evaluation of onion families for male-fertility restoration was completed and linkage to molecular markers assessed. Development of new onion families was initiated for reduced leaf waxiness (associated with tolerance to thrips), dry matter production, and bulb colors. Work continues on the identification of gene conditioning resistance to Zucchini Yellow Mosaic Virus (ZYMV) and the genetic basis of mitochondrial sorting in cucumber. These markers will be used to more efficiently develop lines for commercial production. This will shorten time for hybrid development to reduce development costs and increase grower competitiveness.
In cucumber, several F2 populations have been developed for genetic mapping of horticulturally or biologically important genes. Cucumber genomic resources are being developed (whole genome sequencing and transcriptome sequencing). The genetic diversity among USDA collection of African horned cucumber, a relative of cucumber was evaluated with molecular markers. Also, a national wide survey was conducted to identify research priorities in the public sector.
Bartoszewski, G., Gawronski, P., Szklarczyk, M., Verbakel, H., Havey, M.J. 2009. A One-Megabase Physical Map Provides Insights on Gene Organization in the Enormous Mitochondrial Genome of Cucumber. Genome. 52:299-307. Iovene, M., Wielgus, S.M., Simon, P.W., Buell, C.R., Jiang, J. 2008. Chromatin structure and physical mapping of chromosome 6 of potato and comparative analyses with tomato. Genetics. 180(3):1307-1317. Mccallum, J., Thomson, S., Pither-Joyce, M., Kenel, F., Clarke, A., Havey, M.J. 2008. Genetic Diversity Analysis and Single-nucleotide Polymorphism Marker Development in Cultivated Bulb Onion Based on Expressed Sequence Tag–Simple Sequence Repeat Markers. Journal of the American Society for Horticultural Science. 133:810-818. Ipek, M., Ipek, A., Simon, P.W. 2008. Molecular Characterization of Kastamonu Garlic: An Economically Important Garlic Clone in Turkey. Scientia Horticultureae. 115(2):203-208. Simon, P.W., Cavagnaro, P.F., Chung, S., Szklarczyk, M., Grzebelus, D., Senalik, D.A., Atkins, A.E. 2009. Characterization of a deep-coverage carrot (Daucus carota L.) BAC library and initial analysis of BAC-end sequences. Molecular Genetics and Genomics. 281(3):273-288. Simon, P.W., Pollak, L.M., Clevidence, B.A., Holden, J.M., Haytowitz, D.B. 2009. Plant Breeding for Human Nutritional Quality. Plant Breeding Reviews. 31:325-415. Cuevas, H.E., Staub, J.E., Simon, P.W., McCreight, J.D., Zalapa, J.E. 2008. Mapping of Genetic Loci that Regulate Accumulation of Beta-Carotene in Fruit of U.S. Western Shipping Melon (Cucumis Melo L.) and Their Association With Putative Carotenoid Biosynthesis Genes. Theoretical and Applied Genetics 117:1345-1359. Grzebelus, D., Simon, P.W. 2008. Diversity of DcMaster-like elements of the PIF/Harbinger superfamily in the carrot genome. Genetica. Available: http://www.ncbi.nlm.nih.gov/pubmed/18535910. Khar, A., Jakse, J., Havey, M.J. 2008. Segregations for Onion-Bulb Colors Reveal that Red is Controlled by at Least Three Loci. Journal of the American Society for Horticultural Science. 133:42–47. Meyer, J.D., Deleu, W., Garcia-Mas, J., Havey, M.J. 2008. Construction of a Fosmid Library of Cucumber (Cucumis sativus) and Comparative Analyses of the eIF4E and eIF(iso)4E Regions from Cucumber and Melon (Cucumis melo). Molecular Genetics and Genomics. 279(5):473-480. Al-Faifi, S., Meyer, J.D., Garcia-Mas, J., Monforte, A.J., Havey, M.J. 2008. Exploiting Synteny in Cucumis for Mapping of Psm, A Unique Locus Controlling Paternal Mitochondrial Sorting. Theoretical and Applied Genetics. 117(4):523-529.