Utilization of Different Bmy1 Intron III Alleles for Predicting β-Amylase Activity and Thermostability in Wild and Cultivated Barley

Abstract

The third intron of barley (Hordeum vulgare L.) β-amylase 1 (Bmy1) is extremely polymorphic. The use of specific insertion/deletions (indels) in the third intron as markers for cultivar development has been recommended based on associations with β-amylase activity and thermostability. The third intron of Bmy1 in 40 barley genotypes was sequenced and aligned with 15 Bmy1 intron III sequences from GenBank and four alleles (Bmy1.a, Bmy1.b, Bmy1.c, and Bmy1.d) were identified based on indels of 126, 38, 11, and 21 bp. β-Amylase activity and thermostability were assayed in 22 North American cultivars and 12 wild barley genotypes. Cultivars carrying the Bmy1.a and Bmy1.b alleles had β-amylase activity ranges calculated on a fresh weight (FW) basis of 1.8-and 1.5-fold, respectively, and thermostability ranges of 8.8-and 1.2-fold, respectively. β-Amylase activity calculated on a protein basis yielded a 2.4-and 1.4-fold range for Bmy1.a and Bmy1.b, respectively. Significantly different activities were observed in cultivars carrying either Bmy1.a or the Bmy1.b allele when calculated on a FW basis and the Bmy1.a allele when calculated on a protein basis. Significantly different thermostabilities were observed in cultivars carrying the Bmy1.a allele. Wild barleys were found to carry Bmy1.a, Bmy1.b, and Bmy1.c alleles with β-amylase activity ranges calculated on a FW basis of 1.7-, 1.7-, and 2.6-fold, respectively, and thermostability ranges of 1.3-, 1.4-, and 2.1-fold, respectively. β-Amylase activity measured on a protein basis identified a 1.3-, 1.4-, and 2.1-fold range for Bmy1.a, Bmy1.b, and Bmy1.c, respectively. Significantly different activities were found in genotypes with any of these three alleles when calculated on a FW basis yet only in those with the Bmy1.c allele when calculated on a protein basis. Significantly different thermostabilities in genotypes carrying either the Bmy1.b or Bmy1.c allele were observed. In the germplasm studied here, the Bmy1 intron III alleles are not reliable predictors of β-amylase activity and thermostability.

Variation in β-amylase activity and thermostability in Tibetan annual wild and cultivated barley genotypes

“…In this study, the BAAs and BATs of Tibetan wild and cultivated barleys were compared. As a result, some wild accessions were identified which have higher BAA and BAT than those reported previously (Eglinton et al, 1998;Filichkin et al, 2010;Vinje et al, 2010). These genotypes will be useful for the improvement of malt quality through breeding programs.…”

Differential RNA expression of Bmy1 during barley seed development and the association with β-amylase accumulation, activity, and total protein

“…Sequencing of the Bmy1 gene from Legacy, Harrington, Ashqelon, and PI 296897 showed each had one of the four intron III sequences described by Vinje et al [44] (Supplemental Table 1). The two elite North American malting barley cultivars (Hordeum vulgare ssp.…”

“…vulgare) Legacy and Harrington have the Bmy1.a and Bmy1.b allele, respectively. These two alleles are the only Bmy1 intron III alleles identified to date in the 30 North American cultivars screened [16,44]. The two wild barleys (Hordeum vulgare ssp.…”

“…There are reports that associate variations in Bmy1 intron III sequences with b-amylase activity and b-amylase thermostability [6,14,15,19,23,46]. However, more recent reports did not observe associations between Bmy1 intron III sequences and b-amylase activity and thermostability [16,44,46]. Regardless of the third introns potential use in marker assisted selection, the causes for the observed differences in b-amylase activity between the genotypes reported by Erkkilä et al [14] and Erkkilä [15]have never been ascertained.…”

Differential expression of two β-amylase genes (Bmy1 and Bmy2) in developing and mature barley grain

“…Morex (Clark et al 2005). In contrast, there have been numerous amino acid substitutions reported in the 'endosperm-speciWc' -amylase, encoded by Bmy1, which also has the highly polymorphic third intron (Clark et al 2003;Eglinton et al 1998;Erkkilä et al 1998;Erkkilä 1999;Erkkilä and Ahokas 2001;Filichkin et al 2010;Ma et al 2000Ma et al , 2001Sjakste and Zhuk 2006;Vinje et al 2010Vinje et al , 2011.…”