Progress 10/01/07 to 09/30/12
Outputs
OUTPUTS: The University of Delaware (UDEL) Corn Breeding Program utilizes a broad diversity of germplasm to develop populations and lines for maize improvement and to study the genetics of traits such as disease resistance and environmental adaptation. The program also develops methodologies for crop improvement. In 2011, responsibility for the program was transferred from Dr. James Hawk (who retired from UDEL) to Dr. Randall Wisser. Hawk's projects were phased out and the germplasm he had developed were increased, maintained at UDEL and distributed to collaborators or sent to NPGS. New projects are being initiated by Wisser, and 2011 was primarily dedicated to the development of new genetic stocks. To study the genetics of disease resistance, eight new populations are being developed from exotic or partially exotic inbred lines with resistance to gray leaf spot, Northern leaf blight and Southern leaf blight (identified in a prior study). Backcrosses of four different multiple disease resistant lines (Ki3, NC262, NC304, NC344) are being made to two different multiple disease susceptible lines (H100, Oh7b). In total, 1,200 lines (~150 per cross) were backcrossed or selfed (each of the populations are at various stages of development). This is a collaborative effort with Dr. Peter Balint-Kurti at USDA-ARS NCSU, who is developing the other half of these populations (the complementary set of 1,200 backcross lines). Related to these efforts, Wisser's lab began developing near-isogenic lines of maize that differ in tolerance the herbicide Accent (NICOSULFURON) to investigate the hypothesis that herbicide tolerance genes also confer multiple disease resistance. In a separate study, a comprehensive statistical modeling technique (longitudinal mixed linear model) was examined for the analysis of disease resistance data collected from multiple time points; a manuscript was submitted to Phytopathology. Finally, a database is being developed (extended version of the PANZEA schema [http://www.panzea.org/database/]) to store information about the germplasm produced and characterized by the UDEL Breeding Program. PARTICIPANTS: This project provided researchers and students the opportunity to interact across scientific disciplines to achieve applied objectives related to crop improvement: Lab members included Teclemariam Weldekidan (Research Scientist), Yogasudha Veturi (M.S. student) and Naveen Kumar (M.S. student). Maize breeding summer internships were provided for seven students from the high school level to graduate level. Primary collaborators included Drs. Peter Balint-Kurti, James Holland, and Rebecca Nelson. TARGET AUDIENCES: The results of this project including new germplasm and methodological advances are expected to be useful for both public and private organizations. The statistical modeling approach for analyzing disease resistance data will be of interest to the breeding and plant pathology communities (particularly geneticists and epidemiologists). The database being developed will interest the breeding community. PROJECT MODIFICATIONS: In 2011, responsibility for the University of Delaware (UDEL) Corn Breeding Program was transferred from Dr. James Hawk (who retired from UDEL) to Dr. Randall Wisser. A new, overlapping HATCH project has been defined by Wisser. This is the final report for this project.
Impacts
Papers were published based on studies preceding this reporting cycle that relate to this project. It was found that inbred lines of maize exhibit resistance to multiple diseases, and that a component of multiple disease resistance is associated with individual genes with pleiotropic effects. This led us to initiate new research to further study the genetics of multiple disease resistance, and thus new germplasm is being created in this project. Germplasm development is going according to plan; there are no impacts to report on this. We examined and outlined procedures for implementing a new statistical technique to analyze disease resistance data, which could impact approaches used for disease management. Compared to the current standard method of analyzing disease resistance data using area under the disease progress curve (in which repeated measurements are averaged), the use of a longitudinal modeling technique enabled more detailed comparisons of disease development among genotypes and a broader scope of inference. The technique allows for a more precise analysis of disease resistance and can identify treatments (e.g. genotypes) that effect initial levels of disease development versus rates of disease development.
Publications
- Wisser, R.J., Kolkman, J.M., Patzoldt, M.E., Holland, J.B., Yu, J., Krakowsky, M., Nelson, R.J., and Balint-Kurti, P.J. 2011. Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene. Proc. Natl. Acad. Sci. USA 108(18):7339-7344.
- Wisser, R.J., Balint-Kurti, P.J., and Holland, J.B. 2011. A novel genetic framework for studying response to artificial selection. Plant Genetic Resources: Characterization and Utilization 9(2):281-283.
- Kump, K.L., Bradbury, P.J., Wisser, R.J., Buckler, E.S., Belcher, A.R., Oropeza-Rosas, M.A. , Zwonitzer, J.C., Kresovich, S., McMullen, M.D., Ware, D., Balint-Kurti, P.J., and Holland, J. B. 2011. Genome-wide association study of quantitative resistance to southern leaf blight in the maize nested association mapping population. Nature Genetics 43:163-168.
- Veturi, Y., Kump, K., Walsh, W., Ott, O., Poland, J., Kolkman, J.M., Balint-Kurti, P.J., Holland, J. B., and Wisser, R.J. 2011. The longitudinal mixed linear model: an information-rich statistical technique for analyzing disease resistance data. Submitted to Phytopathology.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: The University of Delaware (UDEL) Corn Breeding Program utilizes a broad diversity of maize germplasm available through the USDA-GEM Project, NCRPIS, and other sources to develop inbred lines with improved agronomic performance and enhanced disease and pest resistance. A comparison of four breeding methods Conventional GEM (CG)(pedigree emphasizing family selection), Conventional Mass (CM)(pedigree with both family and within family selection and more mass selection in the initial breeding cross), Modified Single Seed Descent (MSSD)(bulk of three S1 seeds from each mass selected S0 plant from the CM method, and Doubled Haploid (DH) were compared using three GEM breeding crosses: AR16035:S0209, DKXL212:S0943b, and ANTIG01:N16DE4. Five backcrosses followed by selfing and selection were used to introgress anthracnose stalk rot resistance from MP305 into the susceptible recurrent parent, DE811. The near-isogenic lines (NILs) were crossed to B73Ht and Mo17Ht to produce near-isogenic hybrid (NIHs) which were evaluated to assess fitness costs and to determine the effect of the resistance locus on yield in the presence of disease. PARTICIPANTS: Teclemariam Weldekidan, Research Scientist, Travis J. Frey, and McDonald Jumbo-PhD students. This project provided both students the opportunity to work on an applied breeding project that evaluated the utility of exotic germplasm. Dr. James B. Holland, USDA-ARS at NC State University provided valuable assistance on the statistical analyses. Collaborators include the USDA-ARS GEM Project at both Iowa State and North Carolina State University, and private GEM collaborators AGReliant Genetics, Beck's Hybrids, Hoegemeyer Hybrids, Illinois Foundation Seeds, Inc., Monsanto, Mycogen Seeds, Pioneer Hi-Bred International Inc., Schillinger Seeds, and Syngenta. The American Seed Research Foundation provided funding to support the breeding methodology study. Pioneer Hi-Bred International Inc. Experiment Stations and Disease Resistance Group contributed to the fitness evaluation study using the DE811 and DE811ASR(BC5) isogenic lines. TARGET AUDIENCES: The results of these studies including both germplasm and breeding methodology advances are expected to be useful for both public and private breeding organizations. The near-isogenic hybrid study is expected to be useful for plant pathologists and plant breeders who have an interest in elucidating disease resistance in maize and the utilization of exotic germplasm for disease resistance. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Inbreds developed from exotic germplasm sources should be useful and novel sources for improving yield, agronomic traits, and resistance to pests and pathogens in both sweetcorn and dent corn breeding programs. The DKXL212:S0943b GEM breeding cross, in particular, produced a higher proportion of lines that outyielded the commercial check hybrids compared to other breeding crosses. The results of the breeding methods study indicated that the MSSD method may be an efficient and economical alternative for inbred line development to the DH and conventional breeding methods. The NIH hybrid study indicated that there was no apparent fitness costs associated with the Rcg1 disease locus in uninoculated treatments. Rcg1 also reduced the overall yield loss impact in inoculated plots by almost three-fold compared to the isogenic hybrids that lack the gene. Both studies indicate the importance of genetic diversity and germplasm conservation and evaluation for agronomic and disease resistant traits.
Publications
- Jumbo, M.B., T. Weldekidan, J.B. Holland, and J.A. Hawk. 2011. Comparison of Conventional, Modified Single Seed Descent and Doubled Haploid Breeding Methods for Maize Inbred Lines Development using GEM Breeding Crosses. Submitted to Crop Science.
- Frey, T.J., T. Weldekidan, T. Colbert, P.J.C.C. Wolters, and J.A. Hawk. 2011. Fitness Evaluation of Rcg1, a Locus which Confers Resistance to Colletotrichum graminicola (Ces.) G.W.Wils., using Near-Isogenic Maize (Zea mays L.) Hybrids. Submitted to Crop Science
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: The University of Delaware (UDEL) Corn Breeding Program utilizes a broad diversity of maize germplasm available through the USDA-GEM Project, NCRPIS, and other sources to develop inbred lines with improved agronomic performance, enhanced disease and pest resistance, and improved grain quality traits. A modified single seed descent procedure is being utilized to more efficiently advance S1 families to the S2 and S3 stages prior to testcrossing. A comparison of four breeding methods Conventional GEM (CG)(pedigree emphasizing family selection), Conventional Mass (CM)(pedigree with both family and within family and more mass selection within the initial breeding cross), Modified Single Seed Descent (MSSD)(bulk of three S1 seeds from each mass selected S0 plant from the CM method, and Doubled Haploid (DH) were compared using three GEM breeding crosses: AR16035:S0209, DKXL212:S09043b, and ANTIG01:N16DE4. Although high performing lines were identified using all four methods, a higher proportion of top ten performing lines (based on hybrid yield and yield/moisture performance) were identified from the CM and MSSD methods which utilized more mass selection than the CG and DH methods. PARTICIPANTS: Teclemariam Weldekidan, Research Scientist McDonald Jumbo-PhD student-This project provided McDonald opportunities to work on an applied breeding project that evaluated different breeding methods utilizing exotic germplasm. He gained much practical experience in field techniques, breeding evaluations, and selections. Dr. James B. Holland, USDA-ARS at NC State University provided valuable assistance on the statistical analyses. Collaborators include the USDA-ARS GEM Project at both Iowa State and North Carolina State University, and private GEM collaborators AgReliant Genetics, Beck's Hybrids, Hoegemeyer Hybrids, Illinois Foundation Seeds, Inc., Monsanto, Mycogen Seeds, Pioneer Hi-Bred International, Inc., Schillinger Seeds, and Syngenta. American Seed Research Foundation provided funding to support the breeding methodology study. TARGET AUDIENCES: The results of these studies including both germplasm and breeding methodology advances are expected to be useful for both public and private breeding organizations. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Inbreds developed from the USDA-ARS Germplasm Enhancement of Maize (GEM) Project should be useful and novel sources for improving yield, value added traits such as protein, oil, and starch, agronomic traits, and resistance to pests and pathogens in both dent and sweetcorn breeding programs. The DKXL212:S0943b breeding cross, in particular, produced a higher proportion of lines that outyielded the commercial check hybrids compared to other breeding crosses. The results of the breeding methods study indicated that the MSSD breeding method may be an efficient and economical alternative for inbred line development compared to the DH and conventional breeding methods.
Publications
- Jumbo, M.B. 2009. Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development using GEM Breeding Crosses. Ph.D Dissertation. University of Delaware. Newark DE, USA.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The University of Delaware (UDEL) Corn Breeding Program utilizes a broad diversity of maize germplasm available through the USDA-GEM Project, NCRPIS, and other sources to develop inbred lines with improved agronomic performance, enhanced disease and pest resistance, and improved grain quality traits. High yielding lines with good agronomic performance derived from the USDA-ARS Germplasm Enhancement of Maize (GEM) breeding crosses CUBA164:S2012, DKXL212:S0943b, and DKXL212:S0912 were identified through multiple year testing and are being further evaluated for agronomic and disease performance. Recycled lines from inbred line DE4, derived from the DKXL212:N11a GEM breeding population, have shown a higher yield and yield/moisture performance compared to the commercial hybrid checks. A study was conducted to compare pedigree, modified single seed descent (MSSD), and doubled haploid (DH) breeding methods utilizing three GEM breeding crosses AR16035:S0209, DKXL212:S0943b, and ANTIG01:N16DE4. High performing lines were identified using all methods, but the MSSD had a higher proportion of top ten performing hybrids for the yield/moisture (Y/M) trait compared to the other methods. In addition, there was a lower doubling success for doubled haploids from the Stiff-Stalk GEM breeding crosses compared to more elite populations. The MSSD breeding method may offer an effective and economical alternative to the DH and conventional breeding methods for inbred line development. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: These projects were targeted to serve seed industries and academia. The findings from these projects will help deliver science based knowledge of breeding methods to private and public breeders. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Inbreds developed from the USDA-ARS Germplasm Enhancement of Maize (GEM) project should be useful and novel sources for improving yield, value added traits such as protein, oil, and starch, agronomic traits, and resistance to pests in both dent and sweet corn breeding programs.
Publications
- No publications reported this period
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