Location: Vegetable Crops Research Unit
2008 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.
Genetic basis was determined and selection initiated for carrot, onion, and cucumber quality attributes influencing human health, disease resistances, yield and quality. 50 new entries of carrot germplasm from Tunisia were collected and preliminarily evaluated for phenotypic and molecular variation. Carrot trials were performed in El Centro, CA; Pasco, WA; and Hancock, WI. Cucumber field trials evaluated crop production, sex expression, and pickling quality for Midwest growers. Onion families segregating for health-enhancing fructans demonstrated that two major chromosome regions control fructan accumulation. Construction of genetic maps in carrot, onion, and cucumber was advanced using candidate genes, SCARs, SSRs, SNPs, transposon insertions, BACs, cytogenetic stocks, and the organellar genomes for cucumber plant architecture, mitochondrial sorting, and cold-hardiness; pigment and carbohydrate genes in carrot and onion; resistance genes for nematode in carrot and viruses in cucurbits. Marker-assisted selection of carrot nematode resistance, onion male sterility, and cucurbit yield and quality progressed. Transgene escape in cucurbits was evaluated. Transposon mobility in carrot was observed in genetic maps. 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. This research is relevant to the NP 301 Action Plan, Component 2, Problem Statement 2C: Genetic Analyses and Mapping of Important Traits; and Component 3, Problem Statement 3B: Capitalizing on Untapped Genetic Diversity.
This research is relevant to the NP 301 Action Plan, Component 2, Problem Statement 2C: Genetic Analyses and Mapping of Important Traits; and Component 3, Problem Statement 3B: Capitalizing on Untapped Genetic Diversity.
5.Significant Activities that Support Special Target Populations
Efforts were made attracting under graduate and graduate minorities to the agricultural sciences by participating in annual meetings of the Society for the Advancement of Chicanos and Native Americans in Science (SACNAS) through mentoring and career counseling (ongoing effort started in 1993). Assistance is given for judging student presentations oral and poster sessions, and support is provided to USDA, ARS recruitment in the form of poster displays, organized workshops and symposia, and provided mentoring for undergraduate and graduate students. Symposia (3; genetics/genomics, reclamation, career opportunities in the USDA, ARS) and workshops (4; grant writing, leadership development), and field trips (1; ARS National Water and Cotton Laboratories) have been regularly organized.
Iovene, M., Grzebelus, E., Carputo, D., Jiang, J., Simon, P.W. 2008. Major Cytogenetic Landmarks and Karyotype analysis in Carrot and Other Apiaceace. American Journal of Botany. 95:793-804.
Simon, P.W., Tanumihardjo, S.A., Clevidence, B.A., Novotny Dura, J. 2008. Role of Color and Pigments in Breeding, Genetics, and Nutritional Improvement of Carrots. In: Culver, C.A., Wrolstad, R.E., editors. Color Quality of Fresh and Processed Foods. Washington, D.C.: Oxford University Press. p. 151-165.
Simon, P.W., Freeman, R.E., Vieira, J.V., Boiteux, L.S., Briard, M., Nothnagel, T., Michalik, B., Kwon, Y. 2008. Carrot. In: Prohens, J., Nuez, F. editors. Handbook of Plant Breeding. Volume 2. New York, NY: Springer. p. 327-357.