Location: Plant Science Research2013 Annual Report
1a. Objectives (from AD-416):
1. Identify and develop improved small grain germplasm with resistance to rusts, powdery mildew, Fusarium head blight, necrotrophic pathogens, and freeze tolerance. 1a: Develop wheat germplasm with resistance to stripe rust, leaf rust, stem rust, and powdery mildew. 1b: Develop wheat germplasm with resistance to Fusarium head blight (FHB). 1c: Develop wheat germplasm with resistance to Stagonospora nodorum blight (SNB). 1d: Identify oat, wheat and barley germplasm with tolerance to freezing. 2. Develop improved methods of marker-assisted selection, and apply markers in development of small grains cultivars. 2a: Identify new markers for important traits in eastern winter wheat germplasm. 2b: Evaluate important traits in eastern winter wheat using molecular markers. 2c: Develop new eastern winter wheat germplasm using marker-assisted breeding. 3. Develop new wheat germplasm and cultivars having enhanced end-use characteristics for the eastern U.S. 4. Determine the virulence structure of small grain pathogen populations and evaluate the risk potential of virulence transfer through gene flow. 4a: Determine the virulence frequencies in the wheat powdery mildew pathogen, Blumeria graminis f. sp. tritici, from different regions in the U.S.
1b. Approach (from AD-416):
1. Develop wheat germplasm with resistance to stripe rust, leaf rust, stem rust, and powdery mildew. Develop wheat germplasm with resistance to Fusarium head blight (FHB). Develop wheat germplasm with resistance to Stagonospora nodorum blight (SNB). Identify oat, wheat and barley germplasm with tolerance to freezing. 2. Identify new markers for important traits in eastern winter wheat germplasm. Evaluate important traits in eastern winter wheat using molecular markers. 3. Make new crosses, marker-assisted selection for key traits; phenotyping and selection for improved hard wheats lines; introduce resistance to common bunt; grow and select populations under organic and conventional conditions. 4. Obtain infected plant samples from all states; make single-pustuled isolates, and begin phenotyping and genotyping.
3. Progress Report:
Over 600 wheat powdery mildew isolates from east and west of the Appalachians were created from samples sent by collaborators in 10 states. Virulence data were collected and DNA was extracted for genotyping from all isolates. Next-generation sequencing techniques will be used to identify genetic polymorphism. Population subdivision and migration rates will be estimated, enhancing our understanding of gene flow and the potential for movement of novel virulences. Advanced experimental wheat lines in eastern and southern regional cooperative nurseries were screened under Stagonospora nodorum pressure, and data on resistance provided to breeding programs. Wheat lines exhibiting high levels of S. nodorum susceptibility were evaluated for presence of genes for sensitivity to fungal products that promote disease. The second year of a multi-location field experiment was carried out to gather data for development of a fungicide decision aid for S. nodorum management. Data were collected to expand our understanding of how long wheat heads remain vulnerable to infection by Fusarium graminearum, cause of head scab. This brings to an end a four-year field experiment that is providing a precise picture of levels of disease and mycotoxin present in wheat that is infected at various time points following mid-flowering, when susceptibility is at its peak. This information is helpful in disease and mycotoxin risk projections, and in fungicide management decisions. Freeze test were performed on the Uniform Eastern and the Uniform Southern Soft Red Winter Wheat Nurseries. Freeze-tested and performed an SSR marker analysis of the Uniform Oat and Barley Winterhardiness Nurseries. Performed a Spring-Freeze analysis on the North Carolina Official Variety Test for Wheat and Oats. Established a collaborative investigation with The Canadian Wheat Alliance Program on mechanisms of cold acclimation in wheat. Discovered a technique to image ice formation in frozen crown tissue in 3 dimensions. Continued evaluating freezing tolerance under controlled conditions for the soft red winter wheat community. Produced a full pipeline of hard red and hard white winter wheats, with 1000 crosses/year, 30,000 head rows/year, and 40-70 new elite experimental lines/year. The emphasis is to select lines having superior bread-baking quality. We have focused on Regional testing in North Carolina, Georgia, Louisiana, Kentucky, Virginia, Ohio, and Maryland. We have expanded International testing to Kenya, Turkey, Turkmenistan, Kazakhstan, Pakistan, New Zealand. All early generation lines are genotyped for quality, disease resistance, insect resistance, dwarfing genes, and vernalization genes.
Livingston, D.P., Henson, C.A., Wise, M.L., Tuong, T.D., Tallury, S., Duke, S. 2012. Histological analysis and 3D reconstruction of winter cereal crowns recovering from freezing: a unique response in oat (Avena sativa L.). PLoS One. 8(1): e53468.