Progress 08/21/08 to 04/30/12
Outputs
Progress Report Objectives (from AD-416): Develop maize inbreds and populations with improved host plant resistance to Western corn rootworm (WCR), European corn borer (ECB), and Fusarium ear rot by broadening the genetic base using exotic germplasm. Approach (from AD-416): GEM germplasm will be evaluated for host plant resistance and testcrosses made and further evaluated in yield trials. The most resistant, high yielding germplasm will be recombined and further evaluated utilizing recurrent selection techniques. This project relates to the primary objectives of the parent project which includes the development and evaluation of genotypes for European Corn Borer (ECB), Western Corn Rootworm (WCR), and mycotoxin resistance (fumonisin). The specific breeding objectives of this project was to evaluate GEM materials for their resistance against WCR larvae feeding, recombine new GEM lines with improved levels with the goal of combining different resistance mechanisms, and to continue the Illinois WCR long term recurrent selection program. Initial base populations developed by the USDA-ARS Germplasm Enhancement in Maize (GEM) from the late 1990�s using maize genotypes from Caribbean islands and South America showed improved levels of WCR resistance. The inbreeding process was conducted under insect pressure in the U of IL WCR resistance screening nursery. Inbred lines with improved levels of WCR resistance were developed from GEM populations AR16026:N1210, AR17056:N2025, CUBA117:S1520, FS8A(S) :S0907, and UR13085:N0204. Crosses between inbreds from populations AR16026:N1210 and UR13085:N0204, showed consistently lower root damage ratings (RDR, 0.69 = RDR = 0.84) than the resistant check hybrid PHZ51�NGSDCRW1 (1.52), the susceptible check B37�H84 (2.60), and a commercial non-Bt hybrid (2.54). Work continued on the IL WCR Synthetic in 2011. A bioassay pouch method was developed and used for high throughput phenotyping of WCR seedlings in the greenhouse. The pouch method will also be used to study resistance mechanisms. As part of this effort, El Khishen et al. (2009) studied the resistance mechanism of recently developed genotypes with improved WCR resistance. They reported a group of genotypes, which included AR17056-16 (GEM base population: AR17056:N2025), had less damage, fewer and smaller larvae, and adult beetles recovered than the susceptible controls. Genetic studies in collaboration with AgReliant identified genomic regions for resistance on all maize chromosomes with exception of chromosomes 2 and 4.
Impacts
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Develop maize inbreds and populations with improved host plant resistance to Western corn rootworm (WCR), European corn borer (ECB), and Fusarium ear rot by broadening the genetic base using exotic germplasm. Approach (from AD-416) GEM germplasm will be evaluated for host plant resistance and testcrosses made and further evaluated in yield trials. The most resistant, high yielding germplasm will be recombined and further evaluated utilizing recurrent selection techniques. This project relates to the primary objectives of the parent project which includes the development and evaluation of genotypes for European Corn Borer (ECB), Western Corn Rootworm (WCR), and mycotoxin resistance (fumonisin). Germplasm development and evaluation activities were conducted. A WCR nursery (1,200 rows) was planted May 26, 2011. Materials evaluated were crosses made in 2010 with the objective of combining different Western Corn Rootworm (WCR) resistance genes from diverse exotic backgrounds. Genotypes with adequate WCR resistance were selfed and/or recombined to form new base populations. A set of 50 GEM derived S4 lines with improved WCR was crossed to one tester, and a set of 10 S6 lines were crossed to three testers. Cycle 1 of the Illinois WCR Synthetic was grown in 2011 and 100 randomly selected plants were selfed to continue recurrent selection with S1 progeny. A set of 45 new GEM based F1 hybrids derived from crosses among inbreds developed from AR16026:N1210, UR13085:N0204, CUBA117:S1520, and FS8A(S):S0907 source populations were evaluated for their levels of WCR resistance. All of these materials were also grown under WCR-free conditions and selfed to develop new, segregating F2 populations. A bioassay method is now in progress to evaluate germplasm via use of growth pouches infested with a specific quantity of WCR larvae. The bioassay is designed to enable germplasm evaluation in off-season winter facilities in the Midwest, and to study resistance mechanisms. Monitoring activities included progress reports submitted by the Cooperator in July and December for the Annual GEM Cooperator Meeting. E-mail exchanges were periodically initiated by the Authorized Departmental Officer's Designated Representative (ADODR) or Cooperator on status of experiments during the growing season.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) Develop maize inbreds and populations with improved host plant resistance to Western corn rootworm (WCR), European corn borer (ECB), and Fusarium ear rot by broadening the genetic base using exotic germplasm. Approach (from AD-416) GEM germplasm will be evaluated for host plant resistance and testcrosses made and further evaluated in yield trials. The most resistant, high yielding germplasm will be recombined and further evaluated utilizing recurrent selection techniques. This project relates to the primary objectives of the parent project which includes the development and evaluation of genotypes for European Corn Borer (ECB), Western Corn Rootworm (WCR), and mycotoxin resistance (fumonisin). Although primarily controlled by transgenic Bt hybrids, WCR populations have been known to develop resistance to the Bt toxin under greenhouse conditions. This makes genetic diversity and germplasm resources increasingly more important to develop resistant germplasm for breeders to use. The work in 2010 consisted of germplasm development and evaluation activities. A WCR nursery was established which consisted of new GEM material, segregating F2 progenies involving 10 populations, and 684 genotypes at various stages of inbreeding. These populations were exposed to high WCR pressure to identify germplasm with resistance. Families (first selfing generation) from cycle 0 of the Illinois WCR Synthetic that had high levels of resistance were recombined in summer 2010. Test cross evaluation consisted of 50 S4 inbreds crossed to one tester, and 12 S6 inbreds crossed to three testers. The test cross yield data will be collected in fall. Following analysis of 2009 WCR data, regions of the maize genome were identified which confer resistance to the WCR. Utilizing this information, double haploid (DH) lines were identified to initiate development of germplasm for fine genetic mapping studies, and to combine favorable quantitative trait loci (QTL) by using marker assisted breeding. The methods for monitoring activities included progress reports submitted by the Cooperator in July and December for the Annual GEM Cooperator Meeting. E-mail exchanges were periodically initiated by the ADODR or Cooperator on status of experiments during the growing season.
Impacts
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) Develop maize inbreds and populations with improved host plant resistance to Western corn rootworm (WCR), European corn borer (ECB), and Fusarium ear rot by broadening the genetic base using exotic germplasm. Approach (from AD-416) GEM germplasm will be evaluated for host plant resistance and testcrosses made and further evaluated in yield trials. The most resistant, high yielding germplasm will be recombined and further evaluated utilizing recurrent selection techniques. Significant Activities that Support Special Target Populations This project relates to the primary objectives of the parent project which includes the development and evaluation of genotypes for European Corn Borer (ECB), Western Corn Rootworm (WCR), and mycotoxin resistance (fumonisin). Although primarily controlled by transgenic Bt hybrids, WCR populations have been known to develop resistance to the Bt toxin under greenhouse conditions. This makes genetic diversity and germplasm resources increasingly more important to develop resistant germplasm for breeders to utilize. The work in 2009 is a continuation of research which started five years ago with GEM germplasm. The research effort was devoted to germplasm development and evaluation, including genetic studies for combining ability using diallel analysis, and mapping genes for resistance with molecular markers. For the developmental effort, a WCR nursery was established in summer 2009 that consisted of segregating families derived from four GEM based populations selected in previous years for resistance to WCR and ECB. All germplasm was exposed to high insect pressure by planting in fields which were previously planted with a trap crop of corn-pumpkin mix in 2008. New base populations for breeding were developed in 2009 by intercrossing GEM lines which had good resistance to WCR and ECB. New test crosses were made for future evaluation by crossing a set of 70 S4 inbreds to three tester inbreds of Pioneer Hi-Bred (a GEM Project cooperator). Test crosses of Cycle 0 of the Illinois WCR Synthetic were planted for evaluation and selection for WCR resistance. In addition, to the developmental and evaluation effort, the WCR resistant and susceptible "tails" of the QTL mapping population was re-evaluated. The tails consist of double haploid plants derived from the resistant GEM population AR17056-16 crossed to the susceptible inbred LH51 made through collaboration with AgReliant, the USDA-ARS in Columbia, MO, and the University of IL. The methods for monitoring activities included progress reports submitted by the Cooperator in July and December for the Annual GEM Cooperator Meeting. E-mail exchanges were periodically initiated by the ADODR or Cooperator on status of experiments during the growing season.
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