Allele-Dependent Barley Grain β-Amylase Activity1

Abstract

The wild ancestor of cultivated barley, Hordeum vulgare subsp. spontaneum (K. Koch) A. & Gr. (H. spontaneum), is a source of wide genetic diversity, including traits that are important for malting quality. A high ␤-amylase trait was previously identified in H. spontaneum strains from Israel, and transferred into the backcross progeny of a cross with the domesticated barley cv Adorra. We have used Southern-blot analysis and ␤-amy1 gene characterization to demonstrate that the high ␤-amylase trait in the backcross line is co-inherited with the ␤-amy1 gene from the H. spontaneum parent. We have analyzed the ␤-amy1 gene organization in various domesticated and wild-type barley strains and identified three distinct ␤-amy1 alleles. Two of these ␤-amy1 alleles were present in modern barley, one of which was specifically found in good malting barley cultivars. The third allele, linked with high grain ␤-amylase activity, was found only in a H. spontaneum strain from the Judean foothills in Israel. The sequences of three isolated ␤-amy1 alleles are compared. The involvement of specific intron III sequences, in particular a 126-bp palindromic insertion, in the allele-dependent expression of ␤-amylase activity in barley grain is proposed.

AB-QTL analysis in spring barley: III. Identification of exotic alleles for the improvement of malting quality in spring barley (H. vulgare ssp. spontaneum)

“…Consequently, the exotic alleles may be a source for a-amylases with increased activity, possibly due to better thermostability. Indeed, a more thermostable b-amylase form of the Bmy1 gene has already been identified in wild barley (Erkkilä et al 1998;Paris et al 2002). Sequencing of the Bmy1 locus in ISR42-8 revealed the Bmy1-Sd3 allele which is associated with increased b-amylase thermostability (data not shown).…”

“…Nevertheless, only few studies have attempted to use wild barley to improve malting quality, and these have primarily focused on single genes. Investigation of natural variation in the bamylase gene Bmy1, for example, led to the identification of a new haplotype in wild barley encoding for a b-amylase isoform with increased thermostability (Eglington et al 1998;Erkkilä et al 1998). Only two QTL studies involving exotic germplasm have so far been conducted for malting quality (Pillen et al 2003;Li et al 2005).…”

Haplotyping barley bmy1 using the SNaPshot assay

“…The origin of this variation was thought to reside in the structure of the enzyme, since sequence comparisons demonstrated that the various isozymes differed from one another at both the nucleotide and the amino acid sequence level (Eglington et al 1998;Erkkila et al 1998;Kaneko et al 2000;Ma et al 2001). In particular, Paris et al (2002) were able to identify nucleotide variation at two sites in bmy1, which generated amino acid substitutions, and resulted in four allelic forms which could be associated with the enzymes' thermostability.…”

Integration of the barley genetic and seed proteome maps for chromosome 1H, 2H, 3H, 5H and 7H

“…The weighted malt score is indicated for each cultivar except for Optic and Golden Promise for which data are not available only the Cys115 form was present, while both Cys115 and Arg115 forms were found in Morex (data not shown). The Cys-Arg substitution is due to a single nucleotide polymorphism (SNP) in β-amylase genes (Erkkila et al 1998;Clark et al 2003). In contrast to classical SNP analysis, proteomics illustrates the occurrence of proteins representing the SNP markers, enabling prediction of β-amylase SNP markers in barley cultivars (Finnie et al 2002).…”