Location: Corn, Soybean and Wheat Quality Research
2024 Annual Report
Objectives
Objective 1: Develop accurate and efficient testing methods for processing and marketing quality of soft winter (SW) wheat.
Sub-objective 1a. Develop simple and fast methods for the estimation of wheat grain PHS.
Sub-objective 1b. Improve the existing cracker baking test to make it easier and more widely useable.
Objective 2: Identify SW wheat varieties with various quality characteristics for new food uses.
Sub-objective 2a. Determine the suitability of eastern SW wheat for making tortillas and identify the required quality characteristics.
Sub-objective 2b. Determine the suitability of eastern SW wheat for making white salted noodles and identify the required quality characteristics.
Sub-objective 2c. Develop and evaluate partial and full waxy wheat germplasms for new use.
Objective 3: Develop markers for pre-harvest sprouting using a diverse SW wheat population.
Sub-objective 3a. Find Eastern SW wheat varieties closely related genetically that differ in PHS resistance.
Sub-objective 3b. Locate regions for PHS resistance using a Genome-Wide Association Study (GWAS) on a diverse panel of SW wheat with genotype-by-sequencing (GBS) markers.
Sub-objective 3c. Uncover genes differentially expressed under conditions conducive to PHS versus non-conducive comparing results between lines that are resistant or susceptible to PHS.
Sub-objective 3d. Develop markers for resistance to PHS.
Objective 4: Evaluate and report the milling (processing and intrinsic end-use quality) parameters of SW wheat commercially viable cultivars.
Approach
The Soft Wheat Quality Laboratory (SWQL) aims to improve the end-use quality, uses and marketability of soft winter (SW) wheat in the eastern U.S. by contributing to the development of wheat varieties of improved end-use quality potential and developing new food uses. To attain this goal, the SWQL works to develop reliable and efficient quality testing methods, performs fundamental research on grain characteristics and genetics associated with quality traits, explores potentials of eastern soft wheat for extended uses and performs the comprehensive evaluation of breeding lines for end use quality. The project plan encompasses the effective evaluation of pre-harvest sprouting (PHS) damage and cracker baking quality potential, extended use potentials for tortillas and noodles, genetic factors controlling PHS, and milling and baking quality evaluation of SW wheat, which are crucial for the quality improvement and extended uses of eastern SW wheat.
The required quality characteristics and suitability of eastern SW wheat grain for making tortillas and soft-bite wheat salted noodles will be identified and demonstrated, respectively. Development of partial and full waxy wheat germplasms will be continued, and their potential uses including tortilla and noodles will be examined.
The identification of genetic factors controlling PHS and development of markers for PHS resistance will be conducted in four phases: 1) identify eastern SW wheat varieties closely related genetically that differ in PHS resistance; 2) locate regions for PHS resistance using a Genome-Wide Association Study (GWAS) on a diverse panel of SW wheat with genotype-by-sequencing markers; 3) identify genes differentially expressed under conditions conducive to PHS versus non-conducive comparing results between lines that are resistant or susceptible to PHS; and 4) develop markers for PHS resistance from GWAS and expression analysis.
To contribute to the development of wheat varieties of improved end-use quality potential, the annual evaluation of eastern SW wheat breeding lines for defined milling and baking quality characteristics wil be conducted in collaboration with eastern SW breeding programs.
Progress Report
This project aimed to improve the milling and baking quality and uses of eastern soft wheat varieties by developing accurate and reliable quality testing methods, identifying the associated biochemical and genetic characteristics, and contributing to the development of wheat varieties by conducting the end-use quality evaluation of wheat breeding lines.
Objective 1: Develop accurate and efficient testing methods to determine the processing and marketing quality of eastern U.S. soft winter (ESW) wheat.
Our research continued to develop simple and fast methods for the estimation of wheat grain pre-harvest sprouting (PHS) (Sub-objective 1a). The hot-paste flow distance test, as a simpler and faster alternative to the falling number (FN) test, and provided a reliable estimation of FN. To further increase the throughput of the hot-paste flow distance test, we adopted a grinder requiring less cleaning after each grinding and tested the feasibility of disposable paper sheets and acryl plates to obtain a multi-channel paste flow. The former makes the sample preparation easy and fast, and the latter allows the running of multiple samples at once and requires no to minimal cleaning of paste from the device after each test. A cardstock sheet and acryl plate were identified to yield a hot-paste flow distance closely related to viscosity. The results indicated that the grinder requiring minimal cleaning and a cardstock sheet or acryl plate requiring no to minimal cleaning could be adopted to further increase the throughput of the hot-paste flow distance test for the estimation of PHS.
We further examined the performance of the cracker baking test employing a portable pasta dough sheeter (a stand mixer attachment) and the optimal water amount, which make the test easier to perform and more likely to be widely adopted, using 20 soft wheat flours of varying quality (Sub-objective 1b). The pasta dough sheeter produced dough and crackers comparable to those prepared using the pilot-scale dough sheeter. Much larger differences in weight and thickness of cut cracker dough and weight, thickness, and break force of baked crackers were observed between flours by employing the optimal water absorption instead of the fixed one. The reduction in dough mixing time from 10 min to less than 6 min did not negatively influence dough and cracker characteristics, providing a way to further shorten the experimental cracker baking procedure.
Objective 2: Identify ESW wheat varieties with various quality characteristics for new food uses.
We have elucidated high molecular weight-glutenin subunit (HMW-GS) profiles of ESW wheat suitable for producing tortillas (Sub-objective 2a). HMW-GSs have a major influence on the gluten strength and quality of products requiring gluten development, including tortillas. Thirty-eight ESW wheat cultivars of diverse HMW-GS composition and five commercial tortilla flours were analyzed for protein characteristics and tortilla-making quality to determine the influences of HMW-GSs on tortilla quality. The HMW-GSs 7*+8 showed associations with a small diameter and high rollability score of fresh tortillas, while the HMW-GSs 5+10 showed associations with a small diameter and high opacity score. ESW wheat cultivars carrying HMW-GSs 2+121 produced tortillas with the largest diameter and the lowest opacity and rollability scores, indicating that 2+121 have negative influences on protein strength in the production of tortillas. ESW wheat carrying the HMW-GS profile (2*, 7*+8, 5+10) or (1, 13+16, 5+10) produced tortillas with a relatively small diameter and relatively high opacity and rollability scores, which were most comparable to those prepared from commercial tortilla flours. Increased frequencies of the HMW-GSs 7*+8 and 5+10 are expected to improve the tortilla-making quality of ESW wheat with enhanced gluten strength.
Research continued to identify the HMW-GS profiles of ESW wheat suitable for making noodles (Sub-objective 2b). We evaluated the wheat flours of 25 ESW wheat varieties carrying diverse HMW-GS profiles and four commercial WSN flours for protein characteristics and white salted noodle (WSN) quality attributes including cooking loss and textural properties to determine the influence of HMW-GSs on WSN quality and to identify HMW-GS profiles desirable for making WSN. Eight ESW wheat flours exhibited a protein content and strength comparable to commercial WSN flours and produced WSN of comparable quality to those prepared from commercial WSN flours, with low cooking loss and desirable tensile force and strength. ESW wheat varieties carrying HMW-GSs 2+121 produced WSN with a higher cooking loss and lower hardness, tensile force, and tensile strength than those carrying 5+10, 2+12, or 2+10. ESW wheat carrying the 1BL/1RS rye translocation produced WSN with a higher adhesiveness than those without it, indicating that its absence is desirable for producing WSN. ESW wheat carrying one of three HMW-GS profiles, (2*, 7*+8, 5+10), (2*, 7+9, 5+10), or (2*, 13+16, 2+12), produced WSN with a relatively low cooking loss and adhesiveness, intermediate hardness, and a relatively high tensile force and tensile strength, which were most comparable to those prepared from commercial WSN flours.
We determined the effects of starch amylose content on the quality attributes of WSN (Sub-objective 2c) using wild-type, single-null partial waxy, double-null partial waxy, and waxy genotypes, in which the starch amylose content ranged from 26.8 to 27.8%, 25.5 to 27.0%, 20.4 to 25.9%, and 3.5 to 5.3%, respectively. A reduction in amylose content caused a decrease in the cooking time of WSN. Partial waxy and waxy genotypes required shorter cooking times by 0.5-7.5 min and 6.5-8.5 min than the wild-type genotypes, respectively. WSN hardness and adhesiveness of partial waxy and waxy genotypes were mostly lower than those of wild-type genotypes. Significantly higher WSN cohesiveness than wild-type genotypes by 3.2-6.1% was observed in double-null and triple-null genotypes, and by 3.0% in one of the single-null partial waxy genotypes (B-null), which exhibited a lower amylose content than other single-null genotypes. The B-null and double-null genotypes produced WSN more closely comparable to those made from commercial noodle flours in cooking time and textural properties of cooked noodles than the wild-type, other single-null partial waxy, and waxy genotypes.
Objective 3: Develop markers for pre-harvest sprouting using a diverse SW wheat population.
Research continued to identify chromosomal locations and genes responsible for pre-harvest sprouting (PHS), which causes significant loss of value in soft winter wheat. A diverse population of 188 soft winter wheat varieties encompassing breeding lines from the early 1800s to the early 2000s was tested for PHS resistance under natural, field rain simulation, and growth chamber artificial spike wetting conditions for 3 to 4 years. A total of 1,978 genetic markers at locations across all 21 wheat chromosomes were placed on the population to see if any correlations were found between marker and PHS resistance. Eleven chromosome locations were correlated to PHS by a genome-wide association study and published. A known PHS resistance gene existed near one location. This study also included agronomic and flour quality measurements and found their correlated chromosome locations were different from those of PHS. Thus, breeding for PHS resistance should be possible without disrupting other important crop traits. Two wheat varieties, Scotty and Doublecrop, were identified with a large difference in PHS resistance, but closely related by analysis of 1,978 markers. Relatedness of Scotty and Doublecrop was important to increase the chance of finding genes involved in PHS resistance in the next experiment. The two varieties were used in a published RNA sequencing expression analysis that found 48 genes associated with PHS. Forty-seven were not previously reported as involved with PHS. Two genes that signal the start of PHS were uncovered. One pre-harvest sprouting related gene was found in a GWAS location, common in both. A variety specific resistance marker was developed for it and sequencing continues for the other gene found only in expression analysis to produce a variety specific marker. These markers can be used for PHS resistance screening by wheat breeders but only cover a portion of winter wheat varieties still to be determined in the population due to the multi-gene nature of PHS indicated by the genome-wide association study.
Objective 4: Evaluate and report the milling parameters of commercially viable ESW wheat cultivars.
We have received 3,442 samples harvested in 2023 from nine public and private eastern soft wheat breeding programs, eight uniform regional performance trials, five state variety performance trials, and two research collaborators and conducted comprehensive grain, milling, flour, and baking quality evaluations. The test results were summarized and shared with the breeding programs, directly contributing to the development of new wheat varieties possessing superior quality. We coordinated the Soft Wheat Quality Council (SWQC) Project for the annual evaluation of eighteen new varieties and advanced breeding lines grown in 2023. We arranged the entry grow-out locations, performed pilot-scale milling, distributed flour samples to nine collaborators, performed quality evaluations, analyzed the data, prepared a report that collated quality evaluations among the collaborators, and held a panel review of the evaluation results. We participated in the Pacific Northwest Wheat Quality Project and Michigan State University Wheat Quality Testing Project and evaluated 17 and four advanced breeding lines and varieties, respectively, for flour characteristics and baking quality.
Accomplishments
1. Identification of eastern U.S. soft winter (ESW) wheat potentials and quality requirements for making tortillas. Tortillas are the fastest-growing bakery product in the U.S. market and are typically prepared from hard wheat flour of low protein content or blends of hard and soft wheat of 8.6-10.3% protein. Accordingly, ESW wheat with varying protein characteristics has a great potential to be used for making tortillas when the required flour characteristics are clearly identified and selected for. ARS researchers in Wooster, Ohio, found that about 30% of ESW wheat varieties of relatively high protein content and strength produced tortillas comparable to those prepared from commercial tortilla flours. They also found lower damaged starch content and polyphenol oxidase activity of ESW wheat compared to hard wheat and commercial tortilla flours, which are advantages since these characteristics indicate that ESW wheat requires less water for dough preparation and produces larger and whiter tortillas. It was shown that the ESW wheat flours of high protein content and strength produce tortillas of comparable or better quality than commercial tortilla flours. The information obtained provides guidance for selecting ESW wheat for making tortillas, and will contribute to the increased use of ESW wheat in their production.
2. Genetics of eastern U.S. soft winter (ESW) wheat producing bright white colored noodles. Polyphenol oxidase (PPO) activity is largely responsible for the browning and discoloration of wheat-based products, including noodles, and is primarily controlled by two PPO genes. Noodle brightness is one of the main determinants of consumer acceptance; therefore, the determination of PPO activity and its influence on noodle discoloration are critical for use in noodle production. Selected ESW wheat varieties were proven to carry other quality characteristics suitable for making Asian noodles in a previous study, but their PPO activities and noodle color potentials were not performed. ARS researchers in Wooster, Ohio, found that 20.1 to 36.6% of ESW wheat varieties carry one of the two low PPO gene variants and 7.5% of ESW wheat varieties carry both, and that the latter exhibited low grain and flour PPO activities and produced bright white noodles that showed little discoloration during storage. Increased frequencies of the two low PPO gene variants in ESW wheat are expected to improve the noodle color and discoloration characteristics of ESW wheat with reduced PPO activity, providing guidance to wheat breeders for developing wheat varieties for noodle production.
3. Cell wall gene descriptions developed to understand their role in pre-harvest sprouting. Genes expressed by wheat under pre-harvest sprouting (PHS) conditions were found to be cell wall related. However, comprehensive descriptions and family associations for these cell wall genes did not exist or were incomplete. To better understand the role of cell wall genes in PHS of soft winter wheat, comprehensive associations of genes to previously reported cell wall families from other grass crops was needed. An ARS scientist in Wooster, Ohio, identified 4,086 cell wall related wheat genes by comparing the sequences of wheat proteins to those of rice and maze cell wall gene proteins and grouped them by function. Cell wall gene descriptions in wheat are now comparable to other major grass crops such as rice and maize. Ninety-four cell wall related genes have been identified to be associated with PHS resistance to date using the wheat cell wall gene information. This information helped understand how cell wall related genes can improve PHS resistance in wheat. Future PHS studies will also benefit by improved understanding of how cell wall genes affect PHS resistance.
Review Publications
Penning, B. 2023. The cell wall-related gene families of wheat (Triticum aestivum). Diversity. 15(11). Article 1135. https://doi.org/10.3390/d15111135.
Ma, F., Baik, B.V. 2023. Soft textured wheat with high protein content and strength is suitable for making hot-press tortillas. Cereal Chemistry. 100:1203-1214. https://doi.org/10.1002/cche.10703.
Ma, F., Sturbaum-Abud, A.K., Baik, B.V. 2023. Registration of 12 soft red winter partial waxy wheat germplasms carrying one or two null alleles at the Wx loci. Journal of Plant Registrations. 17:593-598. https://doi.org/10.1002/plr2.20307.