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ARS Home Southeast Area Raleigh, North Carolina Plant Science Research Research





- Brown-Guedira, Gina
- Cowger, Christina
- 2023
- 2022
- 2021
- 2020
- 2019
- 2018
- Publications
- Plant Genetic Resources, Genomics and Genetic Improvement (301)
- Plant Diseases (303)

Research Project: **Location:
                            Plant Science Research** Project Number: 6070-22000-018-000-D
                        
                        Project Type: In-House Appropriated Start Date: Mar 7, 2018
                        
                        End Date: Mar 6, 2023 **Objective:**
                        
                        Objective 1. Identify and develop improved small grain germplasm with resistance to rusts, powdery mildew, Fusarium head blight, necrotrophic pathogens, and tolerance to freezing conditions during winter and spring.
Sub-objective 1a. Develop wheat germplasm with resistance to stripe rust, leaf rust, stem rust, and powdery mildew.
Sub-objective 1b. Develop wheat germplasm with resistance to Fusarium head blight (FHB).
Sub-objective 1c. Develop wheat germplasm with resistance to Stagonospora nodorum blight (SNB).
Sub-objective 1d. Identify oat, wheat and barley germplasm with tolerance to freezing.

Objective 2. Develop improved methods of marker-assisted selection and genomic prediction, and apply markers in development of small grains cultivars.
Sub-objective 2a. Identify and characterize new QTL for important traits in eastern winter wheat germplasm.
Sub-objective 2b. Evaluate important traits in eastern winter wheat using molecular markers.
Sub-objective 2c. Develop new eastern winter wheat germplasm using marker-assisted breeding and genomic selection.

Objective 3. Develop new wheat and barley germplasm and cultivars having enhanced end-use characteristics for the eastern United States.  

Objective 4. Target resistance breeding efforts accurately by determining the relevant geographic variation in pathogen virulence profiles and the range of mycotoxin potential in pathogen populations.
Sub-objective 4a. Determine the virulence frequencies and population structure in the wheat powdery mildew pathogen, Blumeria graminis f. sp. tritici, from different regions in the U.S.
Sub-objective 4b. Identify and determine toxicological importance of minority Fusarium species causing FHB of wheat in North Carolina.

Objective 5: Speed up breeding winter wheat germplasm with resistance to scab using doubled haploid technology. [NP301, C1, PS1A, PS1B] **Approach:**
                        
                        1a. Cross elite, adapted lines with sources of seedling and adult plant resistance to stripe rust, leaf rust, stem rust, and powdery mildew. Coordinate efforts to identify resistant lines in field breeding nurseries evaluated throughout the southeastern United States and in Njoro, Kenya (for Ug99). Evaluation with reliable molecular markers for known resistance genes. 1b. Continue use of inoculated, misted screening nurseries to evaluate regional and in-house breeding materials. Develop, evaluate and refine genomic selection models for scab resistance traits. 1c. Conduct appropriate phenotyping of regional and in-house breeding materials, including mapping populations, in inoculated Stagonospora blight nurseries to assist in locating the genes and associated markers to allow for marker-assisted selection. 1d. Select wheat and oat germplasm with superior resistance to freezing first by identifying genotypic differences in freezing patterns using IR technology. Crosses will be made with adapted cultivars to develop germplasm with improved resistance to freezing conditions. We will continue coordinating an oat and barley uniform nursery.

2a. Use sequencing based genotyping techniques to develop high-density genetic linkage maps of bi-parental mapping populations and association mapping populations as they are developed. Populations are phenotyped in conjunction with other unit scientists to identify regions of the genome involved in resistance to LR, YR, SR, PM, and SNB. 2b. Evaluate diverse germplasm with molecular markers linked to genes for pest resistance, agronomic and end-use quality, determine the level of marker polymorphism and the presence of favorable alleles in breeding lines. 2c. Apply MAS to introgress and pyramid new fungal resistance genes into eastern winter wheat germplasm. Genotype three-way cross and backcross F1s for populations entering into a doubled-haploid (DH) production pipeline. 2c. Use different parameters based on genomic position and linkage disequilibrium to select SNP sets that can be tested via cross-validation to identify the optimum number and most informative markers for GS.

3. Each year, approximately 600 crosses will be made to combine superior quality, yield, agronomic, and disease and insect resistance using recurrent parents from the program, as well as new sources of diversity. Utilize combinations of molecular markers with phenotypic selection and screening to accumulate favorable agronomic traits. Phenotyping and selection for improved hard wheats lines; grow and select populations under organic and conventional conditions.

4a. Samples will be gathered in each of two years from two to five states per region and derive single-pustule isolates; The phenotyping will be done in growth chambers using standard detached-leaf methodology. Population structure will be evaluated using molecular markers. 4b. Scabby wheat spikes will be collected from fields across a broad geographic range of North Carolina. Sequencing of the transcription elongation factor will be used to determine species. Population genetic analyses will determine if the Fusarium species are geographically clustered, or evenly distributed.


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