Allele-Dependent Barley Grain β-Amylase Activity1

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Abstract
The wild ancestor of cultivated barley, Hordeum vulgaresubsp. spontaneum (K. Koch) A. & Gr. (H. spontaneum), is a source of wide genetic diversity, including traits that are important for malting quality. A high β-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 andβ-amy1 gene characterization to demonstrate that the high β-amylase trait in the backcross line is co-inherited with theβ-amy1 gene from the H. spontaneumparent. We have analyzed the β-amy1 gene organization in various domesticated and wild-type barley strains and identified three distinct β-amy1 alleles. Two of theseβ-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 β-amylase activity, was found only in a H.spontaneum strain from the Judean foothills in Israel. The sequences of three isolatedβ-amy1 alleles are compared. The involvement of specific intron III sequences, in particular a 126-bp palindromic insertion, in the allele-dependent expression of β-amylase activity in barley grain is proposed.