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ARS Home » Midwest Area » Madison, Wisconsin » Cereal Crops Research » Research » Research Project #438246

Research Project: Integrated Analysis for Identifying Barley Lines with Superior Malting Quality

Location: Cereal Crops Research

2022 Annual Report

Objective 1. Resolve the genetic basis of dormancy and Preharvest Sprouting (PHS) in malting barley. Objective 1.1: Demonstrate that domestication of barley for improved malting has increased the frequency of mutations within genes that affect dormancy and PHS. Objective 2. Evaluate and report intrinsic malting quality parameters of commercially viable barley cultivars as part of a Congressionally-directed mission of service (non-hypothesis driven). Objective 2.1: Evaluate and report intrinsic barley malting quality parameters used to guide breeder selection for superior variety development and evaluation of new varieties.

We plan to test preharvest sprouting on three unique panels of barley that include lines of contemporary, heritage, and globally diverse origin to reveal the extent of the genetic contribution to dormancy (or nondormancy) together with the screening of these lines for precocious germination on intact heads with the goal of developing genetic resources to reduce preharvest sprouting in North American varieties. The first phase of the approach will examine associations between PHS susceptible phenotypes and allelic variability by using each of the three panels as subjects of genotypic and phenotypic evaluation to 1) to assess sequence variation through a targeted sequencing approach of genes associated with PHS and 2) to develop preharvest sprout scores using mist treatments and germination assays. The second phase will employ a gene discovery-based approach using GWAS on genotyped lines in each of the three populations to identify SNPs (or combinations of SNPs) that can uniquely identify plants carrying alleles that influence PHS related traits. These QTL will fortify our developing panel of novel alleles with additional mutations associated with PHS. Finally, molecular markers targeting SNPs tightly associated with PHS will be developed with the intent of deployment for Marker Assisted Selection (MAS) in malting barley breeding programs. Processing and test procedures are based on the ASBC Methods of Analysis, with some slight modifications and improvements. A base calculation of steep time is generated by determining the average kernel weight (mg) of the sample and using an empirically-determined relationship to yield a base steep time in hours. Slight final adjustments to moisture levels are made prior to moving the samples to the germinator. At this point, we treat all of the submissions equally, using a standardized malting protocol that has been used reliably since 1998. Samples are germinated at 16ºC, 100% humidity, with intermittent turning. An intermediate weight for each sample is taken and a final water adjustment to maintain 45% moisture is made if necessary. After 5 days of germination, the “green malt” is moved to the kiln and the samples are dried for 24 hours, starting with a temperature of 49ºC for 10 h, and rising to 85ºC for last 3 hours. Once the samples are steeped, malted, kilned, and cleaned (rootlets and emergent acrospires removed), they are stored to allow moisture equilibration and sample aging. Samples are subjected to industry standard protocols by the American Society of Brewing Chemists (ASBC). Malts are ground and mashed (ASBC Malt-4) and analyzed for % extract (Malt-4), soluble protein (Wort-17), color and clarity (Wort-9), free amino nitrogen content (Wort-12) and beta-glucan levels (Wort-18). Malt grist is extracted into salt water at 20ºC and the diastatic power (Malt-6) and alpha-amylase activities (Malt-7) are determined. Total nitrogen contents of the barley are determined using FOSS Nova NIT and malt are determined on a LECO Corp. FP528 Nitrogen Analyzer utilizing the Dumas total combustion method (Malt-8).

Progress Report
Progress was made on both objectives. We completed the full sequencing of HvGA20ox1 in over 400 lines spread across three populations. The study identified distinct genetic groups of barley varieties that each have identical mutation patterns and a few of these groups associate strongly with Preharvest Sprouting tendencies. Thus, we believe we’ve identified a suite of genetic mutations that give rise to much of the preharvest sprouting issues in our north American germplasm. We will be developing markers for these mutations that will accelerate selection against preharvest sprouting in malting barley breeding programs. We also micromalted and analyzed the malt characteristics of all the barley lines that were used in the gene sequencing survey and determined that a few of the genes driving dormancy in barley also are strongly correlated to malt quality characteristics. An ORISE fellow from my group has been assessing sensitivity of barley seeds to water logging during germination with the goal of identifying genetic factors that reduce a seed’s ability to germinate in hypoxic environments. The material used for the water sensitivity study is being grown at the west Madison Research station and currently we are in the second year of planting 180 barley varieties from a genetic diversity panel. Additionally, we have incorporated the use of unmanned aerial vehicles (UAV) to rapidly monitor growth characteristics of this population. We hope to further develop our drone-monitoring of barley research plots with the goal of using the data collected from the drone’s spectral sensors to predict malt quality based on growth and spectral characteristics from the maturing grain. In collaboration with an ARS research from Madison, WI and another scientist at the University of Minnesota, we evaluated the beta-glucan content in a panel of wild barley seeds for genetic factors controlling beta glucan concentrations in seeds. Our survey identified regions of the barley genome that affect the amount of beta glucan in the wild barley seeds and further, we demonstrated that these regions account for nearly all genetic contribution to this trait. The Malt quality lab worked diligently to progress through the highest priority samples to meet stakeholder deadlines. Staff from the malt quality lab have been working to catch up on the work missed under maximum teleworking posture and facility occupancy limits. We are happy to announce that we have completed the backlog of user submissions and the data has been disseminated to our customers.


Review Publications
Rogers, C.W., Dari, B., Neibling, H., Walling, J.G. 2022. Barley yield and malt-characteristics as affected by nitrogen and final irrigation timing. Agronomy Journal. 114(2):1461-1474.