2012 Annual Report
1a.Objectives (from AD-416):
The ultimate goal is to enhance the quality of U.S. wheat for domestic and overseas markets. Objectives are to: identify milling, baking, and pasta processing traits of experimental and advanced lines of hard spring and durum wheat that impact end-use quality and the overall development and release of new commercial cultivars of wheat; and identify specific biochemical components in wheat that are associated with end-use baking quality traits. More specifically, the latter objective includes: to develop rapid methods to characterize proteins, which are initially important for predicting end-use quality; to determine the variation in free asparagine content in wheat, which is an important precursor for the formation of carcinogenic acrylamide during bread baking and toasting; and to identify the efficacy and impact of sulfur fertilization on end-use baking quality of hard spring wheat.
1b.Approach (from AD-416):
Approximately 4000 hard spring and 1000 durum wheat experimental lines will be submitted by Federal, State, and private breeders, and special interest groups on an annual basis and evaluated for end-use quality. Wheat will be obtained from different generations of development in specific breeding programs, which will include early-generation, preliminary, and advanced lines and include commercial cultivars as controls. Measureable end-use quality traits include test weight, size, seed weight, sprout damage, physical evidence of disease, and protein and ash content; milling performance as a function of flour and semolina yield; flour and semolina color, protein, and ash content; dough strength properties; bread baking quality; and pasta processing quality. The Fargo Genotyping Laboratory will identify quantitative trait loci regions associated with end-use quality, primarily kernel and dough strength traits on selected hard spring wheat samples. Research will be conducted on the rapid characterization of protein extracts from wheat and flour by testing two different protein extraction methods. Variation in free asparagine content in wheat lines will be measured. The efficacy and impact of sulfur fertilization on end-use baking quality of hard spring wheat, specifically protein composition and amino acid profiles, will be determined as a function of dough strength characteristics.
The Hard Red Spring and Durum Wheat Quality Laboratory (WQL) analyzed the physical and biochemical quality traits on approximately 3000 samples of hard spring and durum wheat and provided over 40 different quality tests. In cooperation with the Wheat Quality Council (WQC), ARS scientists evaluated fourteen experimental lines of hard spring wheat that were grown at up to 4 locations along with the check cultivar, Glenn. The WQL tested each line for kernel, milling, flour, dough, and bread-baking quality traits; coordinated the baking quality test results from 12 independent public and private testing laboratories; and analyzed the data and published the results that were presented and discussed at the annual meeting of the WQC in 2012.
Polymeric proteins in SDS buffer soluble and insoluble proteins were found to have contrasting effects (negative effect for soluble proteins and positive effect for insoluble proteins) on bread-making traits. The SE-HPLC with a micro bore column previously appeared to enhance the speed of analysis of polymeric proteins in wheat and therefore this line of investigation was continued to confirm whether the micro bore column is useful for quality evaluation. Specifically, UV absorbance data of proteins in wheat was collected at 195, 214, 275, and 280 nm using SE-HPLC; proteins were observed to show different responses at those wavelengths. The UV absorbance data will be investigated to determine if it’s useful for quality evaluation.
We also tested UV spectroscopy for rapid characterization of protein extracts. The SDS buffer soluble and insoluble protein fractions were extracted from hard spring wheat flour samples and were scanned at wavelengths between 190 and 350 nm. Absorbance at specific wavelengths was identified to have significant correlations with flour bread making properties. Research will continue to determine if the absorbance data are useful for quality evaluation. Near- and mid- infrared spectroscopy will also be tested for suitability for characterization of protein extracts.
Wheat asparagine concentration is known to influence carcinogenic acrylamide formation during bread baking and toasting, and segregation of low asparagine wheat genotypes is important to reduce acrylamide content in baking products. Pre-harvest sprouting increases free asparagine concentration in wheat. Free asparagine in sprouted wheat samples of 12 hard red and 12 white spring wheat genotypes grown at 3 locations was analyzed by GC-MS. Hard spring wheat genotypes with tolerance to pre-harvest sprouting and low asparagine concentration can be segregated. Asparagine content was analyzed for durum translocation lines that carry chromosome segments for high-molecular-weight glutenin subunits from the D genome of common wheat. These data are currently being analyzed to investigate any genetic association of high-molecular-weight glutenin subunits and asparagine concentration. Asparagine concentration is also currently being analyzed for 75 hard spring wheat lines grown at 3 locations to investigate the effect of genotype and growing location.
Effect of pre-harvest sprouting on wheat proteins and free asparagine concentration. Rainfall before wheat harvest can cause pre-harvest sprouting (PHS) of the wheat kernel, which results in degradation of wheat quality. Work conducted at the ARS Wheat Quality Laboratory in Fargo, ND characterized specific biochemical changes that occur with PHS damage and determined that genetic selection may be useful for mitigating damage from PHS. This information provides breeders and millers with the knowledge needed to improve selection of wheat genotypes for improved PHS tolerance and bread-making quality.
Genetic markers associated with endosperm proteins and end-use quality traits of hard red spring wheat breeding lines. This research was performed in cooperation with wheat breeders from the University of Minnesota to identify genetic markers of endosperm polymeric proteins that are known to greatly affect flour gluten characteristics and thus breadmaking quality. A population of 139 recombinant inbred lines was evaluated in three environments. Eleven genetic markers linked to endosperm polymeric proteins were identified. The DNA markers linked to these polymeric proteins will be useful for breeders in selecting wheat lines that have strong gluten strength characteristics during early generations of breeding.
Prediction of flour breadmaking characteristics. The Mixolab is an instrument that provides data on flour dough thermal characteristics and mixing properties. Use of data from this instrument can be used in mathematical models to predict the quality of wheat varieties under development for commercial purposes. In cooperation with North Dakota State University, ARS scientists in Fargo, ND used Mixolab data to develop highly predictive calibration models for breadmaking parameters in 30 hard red spring wheat flour samples. The development of robust prediction models will facilitate the objective evaluation of wheat flour for breadmaking quality.
Development of improved wheat germplasm. Wheat producers, milling and baking industries, and overseas customers require high standards in the quality of wheat to meet their evolving needs. The ARS Hard Red Spring and Durum Wheat Quality Laboratory (WQL) in Fargo, ND contributed wheat end-use quality data that helped lead to the development of improved wheat germplasm and subsequent release of new cultivars of spring and durum wheat bred for commercial production. Four hard spring wheat cultivars, for which quality characteristics were evaluated in the WQL, were released in 2011-12. Two cultivars, Forefront and Advance, were released by the wheat breeding program at South Dakota State University and two cultivars, Tom and Sabin, by the wheat breeding program at the University of Minnesota.
Tsilo, T.J., Ohm, J., Hareland, G.A., Chao, S., Anderson, J.A. 2011. Quantitative Trait Loci influencing endosperm proteins and end-use quality traits of Hard Red Spring Wheat breeding lines. Czech Journal of Genetics and Plant Breeding. 47:S190-S195.
Simsek, S., Whitney, K., Ohm, J., Mergoum, M. 2011. Refrigerated dough quality of hard red spring wheat: Effect of genotype and environment on dough syruping and arabinoxylan production. Cereal Chemistry. 88(5):445-450.