Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: V. Bmy1 intron III alleles and grain beta-amylase activity and thermostability

Authors: DUKE, STANLEY - University Of Wisconsin; Henson, Cynthia; Vinje, Marcus; Walling, Jason; Bockelman, Harold

Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2018
Publication Date: 1/15/2019
Citation: Duke, S.H., Henson, C.A., Vinje, M.A., Walling, J.G., Bockelman, H.E. 2019. Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: V. Bmy1 intron III alleles and grain beta-amylase activity and thermostability. Journal of American Society of Brewing Chemists. 77(1):62-68. https://doi.org/10.1080/03610470.2018.1546110.
DOI: https://doi.org/10.1080/03610470.2018.1546110

Interpretive Summary: Due to the increased interest in local production of raw materials for microbreweries and craft brewers barley varieties are now being grown in areas of the US that are not traditional barley production areas. This places a demand for either broadly adapted cultivars useful in many growing environments or for cultivars adapted to specific local production sites. As many of the early varieties used in this country and in Canada from the 1880’s through a decade or more after the repeal of Prohibition were broadly grown across North America, were all grown without irrigation, and did not undergo the rigorous malting quality testing used today they may have potential for either immediate use or may provide useful genes for introducing into current malting barley breeding programs. The research described here was designed to compare ß-amylase characteristics in pre-Prohibition with those of modern malting barleys. ß-amylase is widely regarded to be the primary enzyme contributing to the malt quality trait Diastatic Power, which is one of the two most critical malt traits used in commerce.

Technical Abstract: This study was conducted to determine the variation in pre-Prohibition and modern barley malting genotype ß-amylase activities and thermostabilities with differing Bmy1 intron III alleles. Sequencing of the endosperm specific ß-amylase gene Bmy1 intron III of 2- and 6-row of pre-Prohibition barley varieties revealed that both 2- and 6-row varieties had the Bmy1.a intron III allele. This is unusual in that previously there has been only one documented case of a 2-row cultivar having the Bmy1.a intron III allele. All other 2-row cultivars had the Bmy1.b intron III allele. In this study all modern cultivars were found to have the expected Bmy1.b intron III allele and Bmy1.a intron III allele for 2- and 6-row cultivars, respectively. On a fresh weight or unit protein basis the mean ß-amylase activities of modern malting cultivars were significantly higher (P<0.0001) than the mean for pre-Prohibition malting varieties. This indicates that the many years of selection for diastatic power (DP) since the end of Prohibition in North America has boosted ß-amylase activity significantly. Many studies have shown that DP strongly correlates with ß-amylase activity. ß-Amylase activity of modern cultivars with the highest ß-amylase activity were significantly higher (P<0.0001) than all pre-Prohibition varieties. ß-Amylase activity of pre-Prohibition varieties with the lowest ß-amylase activity were significantly lower (P<0.0001) than all modern cultivars. ß-Amylase thermostabilities of modern cultivars were significantly higher (P=0.022) than for pre-Prohibition varieties although the differences for most genotypes be they pre-Prohibition or modern were not great. The 2-row pre-Prohibition varieties Hanna and Hannchen were exceptions, being highly significantly lower (P<0.0001) in thermostability than all other pre-Prohibition and modern genotypes.