POLYMORPHISMS IN THE ALPHA-AMY1 GENE OF WILD AND CULTIVATED BARLEY REVEALED BY THE POLYMERASE CHAIN-REACTION

alpha-Amylases are the key enzymes involved in the hydrolysis of starc h in plants. The polymerase chain reaction (PCR) was used to detect po lymorphisms in the length of amplified sequences between the annealing sites of two primers derived from published alpha-amy1 gene sequences in barley. These two primers (Bsw1 and Bsw7), flanking the promoter r egion and the first exon, amplified two PCR fragments in barley. One o f the amplified products, with the expected length of 820 bp, appeared together with another shorter PCR band of around 750 bp. This 750-bp fragment seems to be derived from an alpha-amylase gene not reported p reviously. Both of the PCR products could be amplified from the two-ro wed barley varieties tested, including cv Himalaya from which the sequ ence information was obtained. Five of the six-rowed barley varieties also have the two PCR fragments whereas another two have only the long fragment. These two fragments seem to be unique to barley, neither of them could be amplified from other cereals; for example, wheat, rye o r sorghum. These two alpha-amylase fragments were mapped to the long a rm of 6H, the location of the alpha-amy1 genes, using wheat-barley add ition lines. Amplification of genomic DNA from wild barley accessions with primers Bsw1 and Bsw7 indicated that both of the fragments could be present, or the long and short fragments could be present alone. Th e results also demonstrated that the genes specifying these two fragme nts could be independent from each other in barley. The conserved band ing pattern of these two fragments in the two-rowed barley varieties i mplies that artificial selection from these genes may have played an i mportant role in the evolution of cultivated barley from wild barley.