Location: Cereal Crops Research
2020 Annual Report
Objectives
Objective 1. Identify, develop, validate, and implement new measurements of malting quality, especially those relating to protein mobilization during germination, in barley germplasm in order to identify those genotypes showing enhanced malting quality attributes. Objective 2. Apply standard malting quality assessments to germplasm submitted by collaborating public sector barley breeding programs, researchers, and other stakeholder organizations in order to identify new (barley) varieties with suitable malting quality attributes.
Approach
Surveying populations that have been extensively genotyped and mapped for malting
quality will allow us to generate datasets that include process (proteinase
activity), phenotype (malting quality), and genotype (>3000 SNP loci) information. Examining a range of barley genetic resources will enable us to use that genetic diversity to identify fundamental processes underlying malting quality. We will use this information to identify new targets and develop additional mechanisms to screen for improved malting barley genotypes. The new screening mechanisms may involve biochemical measurements that we could implement in our malting quality analysis program. Alternatively, the new tests could utilize genetic tools that breeders could incorporate into their own germplasm characterization, simplifying and streamlining their malting quality selection process.
Progress Report
This document represents the final report for expiring project 5090-43440-006-00D titled “Identifying the Next Generation of Malting Barley Through Improved Selection Criteria and Quality Analysis of Breeding Lines." The expired project had goals written for two distinct but cooperative objectives for barley improvement by ARS researchers at Madison, Wisconsin. The first objective had project goals projected for the ARS malt quality analysis team (Malt QA) whose mission was, and still is, to support the public-sector barley breeders and researchers by assessing and reporting the quality of both their barley and malt produced from that barley. The second objective of the expiring report was written to use genetic, biochemical and physiological methods to better understand and subsequently improve malting barley varieties through basic and applied research.
For the life of the project, the ARS researchers at Madison, Wisconsin, have malted and analyzed over 5000 malt barley samples annually and returned the quality scores to public sector barley workers. These analyses assist stakeholders in their selection of material for small scale (pilot) malting and brewing trials to determine suitability of a variety for release with the potential for value added payment. We have steadily implemented new machines and methods to increase the number of samples we can analyze on an annual basis from 5000 per year to close to 7000 per year. The reduced-scale methodologies developed for generating malts and for conducting many standard tests have been adopted by additional barley research programs.
During the current fiscal year, we have substantially progressed toward our projected Malt Quality Analyses support goals. The ARS scientists at Madison, Wisconsin, met over 3700 requests for malting quality analytical data from public-sector barley germplasm enhancement programs and collaborating barley researchers from the 2019 (Spring barleys) and 2018-19 (Winter barleys) crop year. This total included 82 samples malted and analyzed to assist stakeholders in their selection of pilot nursery samples of suitable quality for potential use as recommended malting barley varieties. Prior to ceasing on-site lab operations, we had over 4000 submissions malted by that date, and we intend to resume both malting and analyses to add significantly to that total. Early generation and pilot nursery testing data from our program allowed the American Malting Barley Association Technical Committee, comprised of representatives from the U.S. malting, brewing, and distilling industries, to judge and release ABI Eagle as a new, recommended malting barley variety for 2020, with the potential for value added payment.
Aside from the project contributions by the malt quality analyses team applied and basic research methods were conducted under the project in which ARS scientists at Madison, Wisconsin, worked toward the goal of identifying the next generation of malting barley and improving malt production methods. Over the course of the five year project we have reported on several such findings. One example where we directly addressed method improvement was the enhancement of process controls that are built into standardized malting methods. ARS scientists at Madison, Wisconsin, in collaboration with malt scientists across the United States were able to identify a specific step in the malting process that, previously unbeknownst, can yield a final malt product of variable quality which has been a point of frustration for many maltsters who strive for consistency both within and among their malting establishments. Prior to this study, the inconsistencies observed between malt quality data from different labs were unresolved. By applying the adjustments and control measures established through repeated experimentation, our finding provided a tangible increase in consistency of the malt produced from one malting quality lab to another.
Other significant research highlights included: 1) the first survey and characterization of complete suite of RNA binding proteins in the barley genome; 2) the development of gene expression tools specific to gene expression analysis on malting barley; 3) the characterization of vitamin E and beta-glucan content in barley seeds and the identification of genes controlling these traits; and 4) research into the prevention of preharvest sprouting. RNA binding proteins are key players of RNA metabolism that includes synthesis, processing, editing, modifying, transport, storage and stability of RNA and as a result can have profound effects on the expression of genes. ARS scientists at Madison, Wisconsin, scoured the current genomic sequence of barley for the presence of RNA binding proteins that may play a role specific to malting of barley and found many proteins that were expressed during various malting steps and underscores the important role these proteins play in producing high quality malt.
ARS scientists at Madison, Wisconsin, also reported the development of tools for evaluation of gene expression that are specific to micromalted barley. In short, a suite of malt barley enhanced “reference primers” for quantitative polymerase chaing reaction (PCR) were developed and tested on samples of micromalted barley. These malt specific reference primers are paramount when comparing gene expression results across varieties and developmental time points. Nearly all the primers we developed demonstrated success for use in expression studies. Furthermore, we were able to show that a reduction in the number of these primers used in typical experiment not only yielded high quality data but also saved time and money.
ARS scientists at Madison, Wisconsin, sought to determine how much variation exists in naturally occurring vitamin E content in both cultivated and in wild barley. By first quantifying the eight different isoforms (variant structures) of vitamin E in collections of wild barley and cultivated barley, ARS scientists were able to determine that substantial sources for genetic control over vitamin E biosynthesis exist in the wild barley genome. A collaboration was established with an ARS scientist and university researchers across the United States to genotype a diverse population of barleys for vitamin E biosynthetic genes using a method called genome wide association analysis. This was the first genome wide association study wherein one or more genetic markers associated with one or more vitamin E isoforms were identified close to each of the genes of the pathway to make vitamin E. These genetic markers will provide approaches for breeders and barley improvement scientists to predictably select barleys with enhanced vitamin E content. Several barley lines with very high amounts of vitamin E have been identified that can be useful for breeding barley programs to with improved malting quality, enhanced stress tolerance and/or nutraceuticals for improving human health.
Beta-glucans are naturally occurring polysaccharides that are constituents of cell walls in cereals. Beta-glucans have both positive and negative impacts in post-harvest products made from cereals. In food consumption, beta-glucans have been associated with decreased cholesterol levels however in the brewing industry, high beta-glucan barley causes filtration issues by gumming up the pores. ARS scientists at Madison, Wisconsin, in collaboration with scientists at the University of Minnesota, evaluated the beta-glucan content within a population of over 230 wild barley lines. The study thus far has revealed a wide range in betaglucan content in our wild barley lines, 2-12% which is far greater than the contemporary malting barleys which typically range from 4-6%. Additionally, the research has revealed over 10 putative genes that contribute to the overall beta glucan content in barley.
ARS scientists at Madison, Wisconsin, have been studying the cause of Preharvest Sprouting (PHS) in 2 and 6 row barleys. Defined as precocious germination of seed prior to harvest (i.e. seed that sprouts before it is taken out of the field), PHS results in significant losses to growers of malting barley and therefore presents a tangible risk of reduced returns. By examining hundreds and hundreds of barley varieties, ARS scientists at Madison, Wisconsin, in collaboration with scientists at Montana State University demonstrated that many varieties can resist preharvest sprouting while others are very prone to it. Unraveling the genetic aspects that drive these differing PHS resistance levels will be very important in developing resources and tools for combating the issue. The preliminary results of this project are very promising and as a result the study of PHS resistance in malting barley is the main objective in the next fiveyear plan that is currently under review by the Office of Scientific Quality Review.
Accomplishments
Review Publications
Vetch, J., Walling, J.G., Sherman, J., Martin, J., Giroux, M. 2020. Mutations in the HvMKK3 and HvAlaAT1 genes affect barley preharvest sprouting and after-ripened seed dormancy. Crop Science. 1-10. https://doi.org/10.1002/csc2.20178.
Mahalingam, R., Walling, J.G. 2019. Genomic survey of RNA recognition motif (RRM) containing RNA binding proteins from barley (Hordeum vulgare ssp. vulgare). Genomics. 112(2):1829-1839. https://doi.org/10.1016/j.ygeno.2019.10.016.
