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United States Department of Agriculture

Agricultural Research Service

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Research Project: Broadening the Genetic Base of U.S. Maize with Genes from Unadapted Germplasm

Location: Plant Science Research

2013 Annual Report

1a. Objectives (from AD-416):
1. Manage and coordinate the Southeastern U.S. component of an ongoing, multi-site, cooperative program of maize germplasm evaluation, genetic enhancement, germplasm line development, and information sharing which seeks to broaden the genetic base for U.S. maize. 2. Evaluate a wide diversity of unadapted sub-tropical and tropical maize germplasm for adaptation, yield, and disease resistance. 3. Breed and release genetically-enhanced maize populations and lines, derived from unadapted sub-tropical and tropical maize germplasm, that can contribute to new commercial hybrids, more diverse genetic resistance to biotic stresses, superior yield and other valuable new traits. 3A. Breed and release genetically-enhanced maize lines, derived from unadapted sub-tropical and tropical maize germplasm, that can contribute diverse and valuable new traits to commercial and public breeding programs. 3B. Develop and release a novel set of “adapted” maize races resulting from the allelic diversity (AD) program as tools for gene discovery and genomic research.

1b. Approach (from AD-416):
Exotic sources used for developing new breeding populations will be selected in cooperation with the Ames GEM (Germplasm Enhancement of Maize) coordinator and the GEM Technical Steering Group. Private company cooperators will make the initial crosses between commercial and exotic stocks, and each cooperator has agreed to conduct a specific set of evaluations (e.g. yield trials, abiotic or biotic stress, or breeding cross evaluations) along with evaluations conducted in North Carolina by the Raleigh GEM coordinator. New exotic germplasm sources will be evaluated in testcrosses and then crossed to either proprietary inbreds or formerly proprietary (ex-PVP) inbreds to develop new breeding crosses for further evaluation. These breeding crosses will then be self-pollinated for two generations in disease nurseries to enhance selection of the most promising genotypes, which will be testcrossed and evaluated in yield and disease trials for three seasons. In addition, less agronomically promising sources of exotic germplasm will be backcrossed to elite temperate inbred lines and inbred to create a set of 25% exotic/75% temperate lines that can be used for allele mining and gene discovery.

3. Progress Report:
This new inhouse project replaces the completed inhouse project 6645-21000-027-00D. Two hundred and twenty-five entries were evaluated in first-year trials, ninety-six entries were evaluated in second-year trials, and sixteen entries were evaluated in third-year trials. In the summer of 2013, over 13,500 yield trial plots were coordinated through Raleigh, with approximately 8,400 of those plots planted at NC State and/or NC Dept. of Agriculture locations and the rest with Germplasm Enhancement of Maize (GEM) cooperators. Approximately 2100 GEM nursery rows and 800 isolation rows were planted in summer 2013 at Raleigh. Nursery work involved nineteen different GEM breeding crosses, while one hundred other breeding crosses were observed for agronomic traits of interest and one hundred and ten were included in yield trials to prioritize further utilization. Disease evaluation continues in 2013 for Gray Leaf Spot, where advanced materials were evaluated at three locations in North Carolina (Laurel Springs, Andrews and Salisbury). One hundred and five publically available tropical inbred lines were included in yield trials in 2013 to evaluate agronomic performance. Over 400 nursery rows in Raleigh were devoted to further increasing the genetic diversity in maize through identification of useful alleles in exotic germplasm, which involves accessions that are outside the core plant breeding materials utilized by GEM and most plant breeding organizations. These accessions may contain valuable alleles of interest to breeders that would otherwise not be utilized due to the difficulties in growing tropical germplasm per se in the Corn Belt. The new crosses represent about 65 accessions. The initial steps of the project are coordinated from Raleigh, and the latter steps through Ames, IA; the germplasm produced in Raleigh last summer has been planted by the GEM coordinator in Ames, IA and by GEM cooperators at two locations in Illinois.

4. Accomplishments

Last Modified: 05/23/2017
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