Description and functional analysis of the transcriptome from malting barley

Authors: Vinje, Marcus; HENSON, CYNTHIA - Retired ARS Employee; DUKE, STANLEY - University Of Wisconsin; Simmons, Carl; LEE, KHOA - University Of Minnesota; HALL, EVAN - University Of Minnesota

Submitted to: Barley Improvement Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/18/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: Malting and brewing share a common goal, which is to provide the nutrient solution that brewer's yeast uses to produce alcohol. Two of the major ingredients in malts that must be converted into smaller nutrients that yeast can adsorb are starch and protein. This conversion is the result of specific enzymes that are either present in the dry grain or are made by the grain during the malting process. This study investigated the specific genes that make the enzymes responsible for converting starch to small sugars and how these genes work together during the malting process. Unraveling these complex interactions revealed new enzymes and established the timing of how these genes integrate their actions to produce a high quality malt that is useful to brewers and distillers. Of particular interest is the discovery of a new enzyme which is in the category of enzymes thought to be most important in converting starch to small sugars that yeast use to produce alcohol. The impact of this work is that new opportunities to optimize grain quality and to improve the malting process have been discovered.

Technical Abstract: Deep sequencing of the malting barley transcriptome from an elite malting barley cultivar, Conrad, was undertaken to stablish an early model of the malting barley transcriptome, which describes the expression of genes and their ontologies, identify the period during malting with the largest dynamic shift in gene expression for future investigation, and to determine the expression patterns of all starch degrading enzyme genes relevant to the malting and brewing industry. Large dynamic increases in gene expression occurred early in malting with differential expressed genes enriched for cell wall and starch hydrolases among many malting related categories. Twenty-five of forty starch degrading enzyme genes were differentially expressed in the malting barley transcriptome including eleven alpha-amylase genes, six beta-amylase genes, three alpha-glucosidase genes, and all five starch debranching enzyme genes. Four new or novel alpha-amylase genes, one beta-amylase gene (Bmy3), three alpha-glucosidase genes, and two isoamylase genes had appreciable expression that requires further exploration into their potential relevance to the malting and brewing industry.