Location: Cereal Crops Research
Project Number: 5090-43440-007-00-D
Project Type: In-House Appropriated
Start Date: May 13, 2020
End Date: May 12, 2025
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).