Differentiation of β‐Amylase Phenotypes in Cultivated Barley

Abstract

β‐Amylase types coded by the Bmy1 locus were investigated by analyzing the thermostability and isoelectric focusing (IEF) patterns in 8270 accessions of cultivated barley (Hordeum vulgare L.) from different regions of the world. The β‐amylase types were classified into three main thermostability types (A, high; B, medium; C, low) and three major IEF patterns (I, Ia, and II) together with several rare mutant types. By combined analysis of the thermostability types and IEF patterns, we found 14 β‐amylase phenotypes. Among them, A‐II, B‐I, B‐Ia, B‐II, and C‐II were confirmed to be the major types comprising more than 99% of cultivated barley, and accessions belonging to types A‐Ia, A‐IIa, C‐I, C‐Ia, and C‐IV were reported here for the first time. We also confirmed a clear geographical differentiation of β‐amylase phenotypes: In East Asia, nearly 90% of the accessions were of the A‐II type, while 97% of the Ethiopian accessions were of the C‐II type. The B‐I type accessions were mostly restricted to the former USSR and Europe. In Nepal, Bhutan, India, and Pakistan, 90% of the B type accessions were of the B‐Ia type. The B‐II type barley seems to have originated in Turkey and then mainly spread to North Africa, Europe, and the former USSR.