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ARS Home » Southeast Area » Raleigh, North Carolina » Plant Science Research » Research » Research Project #443938

Research Project: Genetic Diversity and Disease Resistance in Maize

Location: Plant Science Research

Project Number: 6070-21220-017-000-D
Project Type: In-House Appropriated

Start Date: Feb 20, 2023
End Date: Feb 19, 2028

1. Identify and characterize genes and mechanisms underlying disease resistance and defense response in maize. 1A. Characterize quantitative trait loci (QTL) alleles underlying foliar disease resistance and multiple disease resistance in maize and identify the underlying causal genes. 1B. Characterize proteins produced by Peronosclerospora sorghi during infection of maize. 1C. Examine the role of genetic dominance and heterosis in disease resistance using the maize Intermated B73 x Mo17 (IBM) population. 2. Develop improved methods for prediction of yield in different environments and improved understanding of genotype response to environments by collaboration with the maize Genomes to Fields Project. 2A. Coordinate a public competition to predict environment-specific hybrid performance using Genomes to Fields data. 2B. Evaluate diverse landrace introgression stocks and progenies from Germplasm Enhancement of Maize (GEM) line crosses for yield potential across diverse Genomes to Fields environments. 3. Develop agronomically outstanding lines of maize from crosses between elite temperate and diverse exotic germplasm sources as part of the Germplasm Enhancement of Maize Project. 3A. Evaluate adapted and exotic maize genetic resources for maturity, yield, resistance to ear, stalk, and foliar diseases, and tolerance to environmental extremes. Record and disseminate evaluation data via the GEM website, GRIN-Global, and other data sources. 3B. Breed and release maize lines with primarily 50% exotic/50% temperate pedigrees which contribute to U.S. maize more diverse genetic resistance to diseases, tolerance to environmental extremes, higher yield, and other valuable new traits. 3C. Manage and coordinate the Southeastern component of a multi-year, multi-site, cooperative program of maize genetic resource evaluation and information sharing which will broaden the genetic base for U.S. maize. 4. Evaluate and improve corn populations for special culinary uses. 4A. Evaluate landraces of corn from the USA for relationships and utility for specialty corn production. 4B. Develop low protein corn varieties with acceptable agronomic performance.

We will identify candidate genes for disease resistance with linkage mapping and association mapping. Candidate genes will be targeted for knock-outs using gene editing technology. Knock-out stocks will be evaluated for disease resistance. Avirulence genes from rust fungus will be identified by genome sequence comparisons between avirulent and virulent strains. Avirulence genes will be validated by transformation into Nicotiana in combination with the resistance gene from maize, to determine if the combination of genes results in a hypersensitive response. Dominance gene action of resistance genes will be measured in comparison with additive gene action using field evaluations of testcrosses of recombinant inbred lines to both of their parents, generating all three possible genotypic classes at each genome region. Genotype performance across different environments will be measured in the Genomes to Fields project, using experimental designs that optimally balance testing of many hybrids across many environments. Different machine learning techniques for environment-specific hybrid prediction will be compared by conducting a public prediction competition using training and testing data from all available years of Genomes to Fields data. The effects of genomic introgressions from maize landraces will be tested on yield and other agronomic traits in crosses of introgression lines to a common tester and field evaluations in multiple environments. Outstanding Germplasm Enhancement of Maize inbred lines will be created using a multi-step breeding procedure starting with evaluation of exotic sources, crossing to elite commercial lines, selection during inbreeding for adaptation and disease resistance, and finally crossing to elite testers and multiple year yield trials. Sources of exotic germplasm will be evaluated for yield potential when crossed to each of the major breeding groups of USA maize, allowing them to be classified into heterotic groups. Germplasm Enhancement of Maize yield trials will be conducted in collaboration with private sector partners, with data summaries distributed publicly on an annual basis. Germplasm Enhancement of Maize lines will be screened for resistance to important disease and insect pests to identify new sources of resistance. Open-pollinated landraces of maize from the USA will be evaluated in multiple year field trials for a range of agronomic and seed quality traits and genotyped with sequencing to identify genetic and phenotypic relationships among them. Inbred lines with lower grain protein combined with acceptable agronomic performance will be created using pedigree breeding and phenotypic selection methods.