Discovery of Novel Bmy1 Alleles Increasing β-Amylase Activity in Chinese Landraces and Tibetan Wild Barley for Improvement of Malting Quality via MAS

Abstract

China has a large barley germplasm collection which has not been well characterized and is therefore underutilized. The Bmy1 locus encoding the β-amylase enzyme on chromosome 4H has been well characterized in the worldwide barley germplasm collections due to its importance in the malting and brewing industry. The Bmy1 locus was chosen as an indicator to understand genetic potential for improvement of malting quality in Chinese landraces and Tibetan wild barley. The genetic diversity of 91 barley accessions was assessed using allele specific Multiplex-ready molecular markers. Eight accessions were further sequenced, based on the Multiplex-ready marker diversity for Bmy1 in the germplasm. Six of the eight accessions clustered together in a unique group, and showed similarities to ‘Haruna Nijo’, wild barley accession PI296896 and ‘Ashqelon’. Sequence comparisons with the known Bmy1 alleles identified not only the existing 13 amino acid substitutions, but also a new substitution positioned at A387T from a Chinese landrace W127, which has the highest β-amylase activity. Two new alleles/haplotypes namely Bmy1-Sd1c and Bmy1-Sd5 were designated based on different amino acid combinations. We identified new amino acid combination of C115, D165, V233, S347 and V430 in the germplasm. The broad variation in both β-amylase activity and amino acid composition provides novel alleles for the improvement of malting quality for different brewing styles, which indicates the high potential value of the Chinese landraces and Tibetan wild barley.

Differences in hydrolytic enzyme activity accompany natural variation in mature aleurone morphology in barley (Hordeum vulgare L.)

“…Total β-amylase activity did not change over time, consistent with its synthesis during grain development. Free β-amylase activity increased during germination and varied between genotypes, consistent with the release of bound β-amylase and previous reports 16 , 19 , 61 – 63 . Notably, genotype-specific differences in free β-amylase activity at grain maturity correlated with aleurone area, proportion and width.…”

“…Enzymes involved in starch hydrolysis include α-amylase, which hydrolyses α-1,4-glycosidic bonds of starch polysaccharides and β-amylase, which is synthesised during grain development, and during germination acts to liberate the disaccharide maltose from the non-reducing end of starch molecules 16 , 56 – 58 . Function of these enzymes is critical for germination 59 , 60 , and previous studies show that mature grain β-amylase content varies between barley genotypes 61 – 63 .…”

Fine mapping qGL2H, a major locus controlling grain length in barley (Hordeum vulgare L.)

“…Development of tightly linked molecular markers to underlying candidate genes and identification of desirable alleles is necessary for effective MAS. Diagnostic molecular markers have been identified for numerous traits such as waterlogging tolerance (Zhang et al 2016); malting quality (Gong et al 2013;Xu et al 2018b) and disease resistance (Dinglasan et al 2019;Zantinge et al 2019). Despite numerous studies having mapped significant QTL associated with grain size characteristics on all seven barley chromosomes, limited research fine mapping these regions has impacted the development of diagnostic molecular markers for breeding purposes.…”

Improvement of barley genome annotations by deciphering the Haruna Nijo genome

“…Haruna Nijo has a high thermostability of β-amylase, 7 and it also shows different Bmy1 allele for β-amylase activity from Morex. 8 It is also shown that Haruna Nijo has a high malt extract (related to beer production) by QTL analysis. 9 To enhance the utility of Haruna Nijo for breeding, a suite of genomics resources were developed including: an EST collection, transcript map construction, 10 , 11 a BAC library, 12 454-based WGS sequencing 3 and full-length (FL) cDNA sequencing and analysis 13 , 14 (available at , 7 November 2015, date accessed, with functions of expression profiling and genome browsing).…”