ALLELE-DEPENDENT BARLEY-GRAIN BETA-AMYLASE ACTIVITY

The wild ancestor of cultivated barley, Hordeum volgare subsp. spontan eum (K. Koch) A. & Gr. (H. spontaneum), is a source of wide genetic di versity, including traits that are important for malting quality. A hi gh beta-amylase trait was previously identified in H. spontaneum strai ns from Israel, and transferred into the backcross progeny of a cross with the domesticated barley cv Adorra. We have used Southern-blot ana lysis and beta-amy1 gene characterization to demonstrate that the high beta-amylase trait in the backcross line is co-inherited with the bet a-amy1 gene from the H. spontaneum parent. We have analyzed the beta-a my1 gene organization in various domesticated and wild-type barley str ains and identified three distinct beta-amy1 alleles. Two of these bet a-amy1 alleles were present in modern barley, one of which was specifi cally found in good malting barley cultivars. The third allele, linked with high grain beta-amylase activity, was found only in a H. spontan eum strain from the Judean foothills in Israel. The sequences of three isolated beta-amy1 alleles are compared. The involvement of specific intron III sequences, in particular a 126-bp palindromic insertion, in the allele-dependent expression of beta-amylase activity in barley gr ain is proposed.