Location: Plant Introduction Research2009 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
Seven new cooperators joined the Germplasm Enhancement of Maize (GEM) Project. Three were from private U.S. companies, two private International (MayAgro Seed Corp from Turkey; Biomatrix Ltda from Brazil), one U.S. public university (Texas A&M), and the USDA-ARS Crop Genetics and Production Research Unit in Stoneville, MS. 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 include 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 Genetics Research Unit, and Plant Science Research Unit) for mycotoxin, southern leaf blight, grey leafspot, corn root worm, multiple insect resistance, amino acid evaluation, and starch properties for ethanol potential. Approximately 8,254 nursery rows and 300 demonstration plots were planted in Ames, IA by the GEM Project, and 14,390 yield trial plots planted at 56 trial locations with the combined effort of the GEM Project and 13 private cooperators. To maximize nursery resources 24 S1 families were planted as single seed descent (SSD) balanced bulks which resulted in reducing the number of nursery rows from 6,000 to 408. Approximately 369 nursery rows were devoted to the Allelic Diversity (AD) project which comprised 70 races from 10 countries. In addition, approximately 677 rows were planted to potential haploid families in 2009 which were generated last year and identified this winter by scoring kernels for the presence of a marker on the seed cap. Approximately 413 rows were planted for induction of new haploid lines for the 2009 season. Studies were also initiated for methods of doubling chromosome numbers to make double haploids (DH) without the use of colchicine. The DH 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. Efforts are continuing to create an exotic mapping population using CUBA164 (PI 489361) as the elite exotic source identified in the GEM Project. The first selfing (S1) generation was made from the backcross (BC) families to create the BC1S1 generation of 248 families of (CUBA164 x B73) x B73, and 248 families (CUBA164 x PHB47) x PHB47.
1. Photoperiod control structure. Utilizing tropical germplasm in Midwest environments is limited by the effects of photoperiod response which delays flowering time. During the past two years various types of shade house structures were successfully used to ensure that tropical maize flowered similar to temperate germplasm permitting crosses to be made in the Midwestern nursery. An enlarged and cost efficient shade house was created by the GEM and Maize Curatorial Projects utilizing the principles of a grain trailer roll tarp. The enlarged shade house (100 feet x 40 feet) accommodates 93 rows and effectively triples our capacity above the seven shade structures that were used in 2008. The impact of this accomplishment may result in greater utilization of tropical germplasm in Mid-western maize introgression programs potentially broadening the germplasm base.
Li, L., Jiang, H., Campbell, M., Blanco, M.H., Jane, J. 2008. Characterization of Maize Amylose-Extender (ae) Mutant Starches. Part I: Relationship Between Resistant Starch Contents and Molecular Structures. Carbohydrate Polymers. 74(3):396-404.