Research Project: Genetic and Physiological Mechanisms Underlying Complex Agronomic Traits in Grain Crops

Location: Plant Genetics Research

Project Number: 5070-21000-041-000-D
Project Type: In-House Appropriated

Start Date: Feb 20, 2018
End Date: Feb 19, 2023

Objective:
Objective 1: Identify genetic and physiological mechanisms controlling growth under drought in maize, wheat, and related species. • Sub-objective 1.1: Characterize the genetic regulation of maize root growth responses to soil water-deficit stress. • Sub-objective 1.2: Determine the roles of plant hormones abscisic acid (ABA) and gibberellins (GA) in the regulation of wheat root responses to water deficit. • Sub-objective 1.3: Characterize the genetic networks that link transcription factor expression and metabolism central to cellular protection during dehydration in a C4 resurrection grass. Objective 2: Characterize corn for natural rootworm resistance, rootworm larvae for Bt tolerance, and artificial diets for improved understanding of rootworm biology and management. • Sub-objective 2.1: Systematically screen exotic and Germplasm Enhancement of Maize (GEM) germplasm, identify potential sources of western corn rootworm (WCR) resistance, verify resistance, and move into adapted germplasm. • Sub-objective 2.2: Characterize heritability and other traits of rootworm larvae with Bt tolerance. • Sub-objective 2.3: Evaluate northern corn rootworm (NCR) development on larval Diabrotica diets and develop a diet toxicity assay for NCR. Objective 3: Identify genetic and physiological mechanisms governing response to artificial selection in cereals and related species. • Sub-objective 3.1: Develop an experimental evolution maize population to characterize adaptation to selective pressures at the genomic level in maize and related species. • Sub-objective 3.2: Quantify the importance of epistasis with novel Epistasis Mapping Populations. • Sub-objective 3.3: Develop, implement, and validate statistical methods to better understand traits controlled by multiple genes acting in concert. Objective 4: Develop and characterize germplasm to elucidate the genetic mechanisms underlying nutritional and food traits in maize. • Sub-objective 4.1: Screen and develop maize germplasm for traits important in food-grade corn. Objective 5: Identify genetic and physiological mechanisms underlying maize adaptation to the environment to enhance its productivity. • Sub-objective 5.1: Develop and evaluate germplasm segregating for adaptation to high elevation. • Sub-objective 5.2: Evaluate diverse maize hybrids in multi-location trials as part of the Genomes To Fields Genotype x Environment Project.

Approach:
Conduct genome-wide association analysis of water-stress root growth using high-throughput maize root phenotyping to link transcription factor (TF) expression with root growth phenotypes under stress. Characterize water deficit growth and hormone responses in wheat roots, and interrogate the gene expression profiles (RNAseq) for the root growth zone. Use chromatin immunoprecipitation-sequencing to establish the role of transcription and TF targets in the response of both wheat and maize roots to water deficits. Develop gene network maps for dehydration TFs in the resurrection grass Sporobolus stapfianus. Evaluate 75 new sources of maize germplasm each year for resistance to Western Corn Rootworm (WCR) larval feeding in replicated field trials. Develop an artificial diet for Northern Corn Rootworm (NCR) and conduct toxicity assays for all available Bt proteins. Expose NCR populations to current industry Bt corn in plant assays and measure the effect on insect development. Evaluate the inheritance of Bt resistance in WCR. Conduct five cycles of selection for high and low plant height in the Shoepeg maize landrace population, followed by genotyping and selection mapping. Phenotype an Epistasis Mapping Population and conduct statistical tests for epistatic effects. Screen 100 heirloom maize varieties for adaptation to the southern Corn Belt and make selections based on agronomic performance and kernel composition traits. Create and release modified open pollinated varieties with improved performance and food characteristics. Conduct quantitative trait locus (QTL) mapping of traits related to highland adaptation in maize populations grown at low, mid, and high elevations. Compare QTLs identified in a Mexican and South American germplasm. Identify candidate genes based on traits related to adaptation and fitness at varying elevation. Participate in multi-location yield trials to evaluate diverse maize hybrids across the US.