2013 Annual Report
2. Develop, modify, and evaluate technologies and methodologies for measuring wheat kernel characteristics that impact end use functionality. Specific characteristics to be measured include: Kernel texture (sub-objective 2a), arabinoxylan composition (sub-objective 2b), gluten quality (sub-objective 2c) and polyphenol oxidase activity (sub-objective 2d). Sub-Objective 2a. Determine the reliability and performance of an endosperm brick test developed at the WWQL. Sub-Objective 2b. Develop a diagnostic assay for oxidative gelation of arabinoxylans in flour batters using free-radical-induced/peroxidase-mediated oxidative cross-linking. Sub-Objective 2c. Test a recently developed laser-based prototype instrument for measuring gluten strength via SDS-sedimentation (in collaboration with Dr. Rangan Chinnaswamy, GIPSA) Sub-Objective 2d. Modify our existing PPO L-DOPA assay to identify very low levels of grain PPO.
3. Identify and manipulate the biochemical constituents of wheat to improve the nutritional functionality of grain and flour, specifically dietary fiber and antioxidant content.
3. A comprehensive survey of soft wheat grain quality in U.S. germplasm. An ARS scientist in Pullman, Washington, with collaborators at Washington State University conducted a comprehensive survey of soft wheat grain quality in U.S. germplasm. Comparisons of soft wheat from eastern and western regions, including winter and spring, red and white wheats has not been conducted. Elite germplasm from regional nurseries were evaluated for milling and baking end-use quality. In general, soft wheat quality is relatively uniform across America. However, significant variation exists in each class. 4. Segregation analysis of puroindoline b2 variant genes. ARS scientists in Pullman, Washington, in cooperation with Washington State University, and Chinese Academy of Sciences, studied the segregation of puroindoline b2 variants in wheat. The relationship between puroindoline b2 variants 2 and 3 is not known. Segregation analysis among three spring wheat populations was conducted The results indicate that the two forms are allelic. The results provide an evolutionary framework for this gene in wheat and indicate that these two forms share an evolutionary history. 5. Expression of puroindoline b2 genes in wheat. An ARS scientist in Pullman, Washington, in cooperation with Montana State University studied the expression of puroindoline b2 genes in wheat. The level of expression of puroindoline b2 variants is not known. Puroindoline b2 variants 1-4 were measured using mRNA. Expression ranged from near zero to nearly 8% of puroindoline a and b levels. Given the very low level of puroindoline b2 expression, it is unlikely that these genes contribute to grain softness in wheat. 6. Prevalence of puroindoline b2 genes in Pacific Northwest wheat breeding germplasm pools. ARS scientists in Pullman, Washington, with collaborators at Washington State University, and a scientist with the Chinese Academy of Agricultural Sciences surveyed the puroindoline b2 genes in Pacific Northwest soft white, hard red and hard white wheat breeding germplasm. Puroindoline genes may influence kernel properties and end-use quality. The puroindoline genes were determined among 388 wheat varieties and breeding lines, and evaluated against kernel texture. Specific gene variants were present according to germplasm pool, for example, hard red spring versus hard red winter. There was no association of puroindoline b2 genes with kernel texture variation indicating that this gene does not play a direct role in end-use quality.
Chen, F., Shang, X., Morris, C.F., Zhang, F., Dong, Z., Cui, D. 2013. Molecular characterization and diversity of puroindoline b-2 variants in cultivated and wild diploid wheat. Genetic Resources and Crop Evolution. 60:49-58.
Geng, H., Beecher, B.S., He, Z., Morris, C.F. 2012. Physical mapping of puroindoline b-2 genes in wheat using the 'Chinese Spring' chromosome group 7 deletion lines. Crop Science. 52:2674-2678.
Kiszonas, A.M., Fuerst, E.P., Morris, C.F. 2013. A comprehensive survey of soft wheat grain quality in United States germplasm. Cereal Chemistry. 90:47-57.
Geng, H.W., Beecher, B.S., Pumphrey, M., He, Z.H., Morris, C.F. 2013. Segregation analysis indicates that Puroindoline b-2 variants 2 and 3 are allelic in Triticum aestivum L. and that a revision to Puroindoline b-2 gene symbolization is indicated. Journal of Cereal Science. 57:61-66.
Giroux, M., Kim, K., Hogg, A., Martin, J., Beecher, B.S. 2013. The puroindoline b-2 variants are expressed at low levels relative to the puroindoline D1 genes in wheat seeds. Crop Science. 53:833-841.
Geng, H., Beecher, B.S., He, Z., Kiszonas, A., Morris, C.F. 2012. Prevalence of puroindoline b-2 variants in U.S. Pacific Northwest wheat breeding germplasm pools, and their association with kernel texture. Theoretical and Applied Genetics. 124:1259-1267.