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United States Department of Agriculture

Agricultural Research Service


Location: Plant Introduction Research

2008 Annual Report

1a. Objectives (from AD-416)
The long-term objectives of this project are to identify and incorporate useful maize genetic diversity to support sustainable productivity of the most important crop in the United States, as measured by acreage planted, farm gate value, product value and strategic importance. To accomplish this, we will: 1) manage and coordinate a multi-site, cooperative program of maize germplasm evaluation, genetic enhancement, inbred line development, and information sharing focused on broadening the genetic base for U. S. maize; 2) evaluate maize germplasm with a broad spectrum of non-U.S. and mixed U.S./non-U.S. pedigrees for adaptation, yield, resistance to biotic and abiotic stresses, and key value-added traits; 3) breed and release genetically-enhanced populations and inbred lines, derived from non-U.S. and/or mixed U.S./non-U.S. germplasm sources, that are commercially-competitive and/or which contain key traditional or novel traits; and 4) develop innovative means of managing and transferring evaluation and breeding information to multiple project cooperators and germplasm users.

1b. Approach (from AD-416)
Extensive collaboration efforts on the part of 60 current cooperators from the private, public and international sectors are required to broaden the germplasm base in effective ways that provide germplasm of use for food, feed, fuel, and industrial applications by producers and end-users. The Coordinator serves as the liaison for collaborators and the Technical Steering Group (TSG), selects germplasm, facilitates germplasm acquisition and stakeholder interactions, arranges for in-kind-support, information sharing, and technology transfer. The Ames location will develop germplasm derived from 50% and 25% exotic breeding crosses developed by crossing tropical and temperate racial accessions with adapted, elite proprietary Corn Belt lines. Approximately 1,500 -1,600 S2 top crosses will be made and evaluated annually in yield trials, disease nurseries, and for value-added traits such as ethanol, protein, oil, and starch. Germplasm will be further evaluated by a network of cooperators with expertise, facilities, and favorable selection environments for the traits of interest. Important traits include mycotoxin resistance, abiotic stress tolerance, and insect resistance. Germplasm lines will be released to cooperators and selected lines registered and publicly released. Released lines will be maintained by the National Plant Germplasm System's maize curator. An effort will be made to develop lines derived from approximately 250 races of maize to broadly represent the allelic diversity of the maize races. Initial crosses of racial accessions with expired PVP lines or other public lines are made in winter nurseries, and one backcross to the adapted line (BC1). The resulting BC1 generation will be used for selecting lines in Midwest nurseries in order to release a unique set of (F5 generation) adapted, racial derivative lines for research and discovery applications. Technologies and methodologies can be utilized such as SNP or SSR markers for genomic profiling and association analysis that offer potential to translate genomic knowledge to germplasm enhancement and utilization applications. Genotypes will be screened in selected environments to maximize selection for priority agronomic, biotic and abiotic stress, reduced mycotoxin, and value-added traits.

3. Progress Report
This is the first report of the new Project and covers the period February 5, 2008 until September 30, 2008. Six new cooperators joined the Germplasm Enhancement of Maize (GEM) Project. Four were from private U.S. companies, one public International (Chinese Academy of Agricultural Sciences), and the USDA-ARS Mycotoxin Research Unit in Peoria, IL. The new cooperators will expand our access to exotic germplasm by making new breeding crosses, and enhance our ability to evaluate and develop germplasm for reduced levels of mycotoxin. Other research collaborations in progress with the public sector included germplasm evaluation and development with five USDA-ARS research units (Crop Genetics and Breeding Research Unit, Corn Host Plant Resistance Research Unit, Corn Insects and Crop Genetics Research Unit, Plant Genetic Resources Unit, and Plant Science Research Unit) for mycotoxin, southern leaf blight, grey leafspot, corn root worm, multiple and amino acid evaluation and starch properties for ethanol potential. The 2008 planting season was a challenge due to the Midwest floods and some plots were planted late, and/or flood damaged (less than 5% overall). Approximately 5,825 nursery rows and 300 demonstration plots were planted in Ames, IA by the GEM Project, and 17,833 yield trial plots planted with the combined effort of the GEM Project and 16 private cooperators at 57 trial locations. To maximize nursery resources 22 S1 families were planted as single seed descent (SSD) balanced bulks which resulted in reducing the number of nursery rows from 5,500 to 370. Approximately, 466 nursery rows were devoted to the Allelic Diversity (AD) project which comprised 39 races from 11 countries. A new technology applied to the AD project was making crosses with a double haploid (DH) inducer working with a cooperator at the Iowa State University Agronomy Department. Following harvest, individual ears will be examined and selected for DH kernels for future chromosome doubling. This technology has not been extensively explored with exotic germplasm and has great potential to enhance progress for rapid release of adapted lines derived from racial materials. Research is also continuing on the applicability of using shade houses to reduce photoperiod response in 19 exotic tropical germplasm sources. The first backcross (BC1) was made for 292 F1 families of CUBA164 to the two recurrent parents to create an elite exotic mapping population. Progress by the GEM Project relates to the National Program 301 Action Plan, Component 3, Genetic Improvement of Crops, Problem Statement 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.

4. Accomplishments
1. New germplasm acquisitions for integration into the Germplasm Enhancement of Maize (GEM) Project The Latin American Maize Project (LAMP) has been the primary source of exotic germplasm used by the GEM Project. To broaden the germplasm base, the coordinator participated with the Technical Steering Group (TSG) to identify, and acquire new sources of exotic germplasm. As a result, 23 breeding crosses were acquired from GEM Cooperators in Thailand, four breeding crosses from Peru and France respectively, three silage accessions from Chile, five accessions for Mal de Rio Cuarto disease (Argentina), and three for maize streak (Nigeria). The impact of this accomplishment is to provide new sources of germplasm to the GEM Project, which potentially will broaden the germplasm base, and provide new sources of disease resistance. This accomplishment falls under National Program 301 Action Plan, Component 3, Genetic Improvement of Crops, Problem Statement 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.

2. Using shade houses to reduce photoperiod response in tropical germplasm Utilizing tropical germplasm in Midwest environments is limited by the effects of photoperiod response which delays, or restricts flowering. Nineteen additional tropical sources were studied in 2008 and a significant reduction in flowering time was found in most of the sources studied which enabled regeneration, and pollination crosses with Midwest germplasm. The impact of this accomplishment may result in greater utilization of tropical germplasm in Mid-western maize introgression programs. This accomplishment falls under National Program 301 Action Plan, Component 3, Genetic Improvement of Crops, Problem Statement 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.

5. Significant Activities that Support Special Target Populations

Last Modified: 2/23/2016
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