Wednesday Nite at the Lab
press release: WN@TL goes hybrid both with Zoom and with in-person (Room 1111) presentations. The zoom registration link is still go.wisc.edu/240r59. You can also watch a live web stream at on YouTube.
On January 18 Marcus Vinje of the USDA’s Agricultural Research Service, Cereal Crops Research Unit, speaks to us on our state’s most favoritest small grain: barley. Also, he’ll give us insights into one of our state’s most-flavored enzymatic processes: malting. Think what it means to take something bland (such as starch) and cleave it into something sweet (such as glucose). If you’re a yeast, malt makes for a tastier feast.
Bio: Marcus Vinje earned his B.S. in Genetics (’04) and Ph.D. in Agronomy (’09) from the University of Wisconsin-Madison. Since 2012, he’s been a Research Geneticist at the USDA-ARS, Cereal Crops Research Unit in Madison, WI studying barley grain development and malting. His lab is interested in understanding the regulation and expression of genes associated with malting quality traits with a focus on diastatic power enzyme genes. Additional interests include identifying new or novel genes that influence malting quality traits and characterizing newly discovered genes that might influence malt quality. Dr. Vinje is on the editorial board of the Journal of the American Society of Brewing Chemists and has published 21 peer-reviewed articles related to barley grain development and malting.
Description: This talk focuses on malting barley research at the USDA-ARS, Cereal Crops Research Unit (CCRU) and briefly discusses the history of the Cereal Crops Research Unit and its long-time partnership with the University of Wisconsin-Madison. Much of the presentation will focus on my work with the b-amylase gene family, identifying new genes of interest from sequencing the malting barley transcriptome, and studies on a barley transcription factor mutant.
The forerunner of the CCRU started after prohibition in 1934 and was located in the basement of UW-Madison’s Moore Hall (Dept. of Agronomy). In 1949, the Barley Malt Lab was built on the west side of campus for malting barley research and housed the CCRU until 2006, when they moved to their new building across the street at 502 Walnut Street.
The CCRU is home to four research laboratories, a greenhouse, and a malting quality lab. The malting quality lab malts and analyzes close to 6000 malting quality lines each year for public U.S. malting barley breeders. We have four full-time research scientists studying various aspects of malting quality. Our Research Leader, Dr. Mali Mahalingam’s research is on genetic basis of climate resiliency in plants with a focus on identifying and characterizing barley germplasm with tolerance to heat and drought while still meeting malt quality. Dr. Jason Walling is the director of the malt quality lab, and his research is focused on understanding the genetics of pre-harvest sprouting and malt quality traits. Dr. Sarah Whitcomb is our newest addition, and her research is on determining key metabolites involved in malting and their relation to malt quality.
I’ve been studying various aspects of barley malt quality for close to two decades. A lot of my research has centered around the b-amylase gene family. b-Amylase is an enzyme that releases a b-maltose unit from a-glucan chains and is primarily responsible for the enzymatic activity that determines diastatic power, an important malting quality parameter that measures the malt’s ability to break down starch into fermentable sugars. My early career research centered around identifying Bmy1 molecular markers that could accurately predict b-amylase activity and thermostability in wild and cultivated barley and studying a lesser known b-amylase gene, Bmy2. b-Amylase encoded by Bmy1 is thermolabile and is denatured in common mashing temperatures.
Mashing is the brewing step where crushed malt is soaked in hot water to allow for the enzymatic conversion of macromolecules into their component parts (e.g., starch to fermentable sugars). However, Bmy2 encodes a more thermostable enzyme, and was found to be expressed during malting, whereas Bmy1 is not, indicating potential to improve malt quality. Two Bmy2 mutants (CRISPR knockout, overexpression) have been generated to further explore Bmy2’s influence on malt quality. Sequencing the malting barley transcriptome identified another b-amylase gene, Bmy3, that was highly expressed during malting. In addition to Bmy3, two other genes of interest were found in the transcriptome encoding for a previously unknown a-glucosidase and isoamylase (Agl4, ISA1_2). Characterization of these genes are underway to assess their expression patterns and to determine if they encode for functional enzymes. In partnership with the Wisconsin Crop Innovation Center, a triple b-amylase mutant (Bmy1, Bmy2, Bmy3) was designed and is currently in production.
Understanding the regulation of malting quality genes is another research goal being explored. Diastatic power and grain protein are two positively correlated malting quality traits, and their correlation is problematic since brewers typically want high diastatic power but low protein. Hordeins are the primary seed storage protein in barley and their expression is a major determinant of total grain protein levels, whereas b-amylase expression and activity are responsible for diastatic power. The hordein gene family (Hor1, Hor2, Hor3, and Hor5) and Bmy1 were found to be co-expressed during grain development implying a common transcription factor controlling their regulation in early to mid-grain development. Further exploration of the co-regulation of hordeins and b-amylase was undertaken using a barley mutant, lys3a, known to be deficient in hordein and b-amylase.
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