N-terminal amino acid sequences of prolamins encoded by the alleles at thePro1 and Pro2 loci in foxtail millet, Setaria italica (L.) P. Beauv.

N-terminal amino acid sequences of six prolamins encoded by seven alleles a t two loci, Pro1 and Pro2, of foxtail millet (Setal ia italica (L.) P. Beau v) were analyzed and compared with other prolamins of subfamily Panicoideae . Based on the N-terminal amino acid sequences, band 3 (the prolamin purifi ed from band 3) which is controlled by an allele at the Pro1 locus and band s 1, 2, 4, 5 and 6 which are controlled by alleles at the Pro2 locus could be classified into three groups. Band 3 was found to be homologous to the p rolamin of pearl millet (Pennisetum americanum) and is designated as the "p ennisetin-like prolamin". Bands 2 and 4, and bands 1, 5 and 6 were subdivid ed into "x-type prolamin" and "y-type prolamin". Both of the x-type and y-t ype prolamins showed homology with prolamin of Echinochloa crus-galli and a lpha-zein-like prolamins of maize, sorghum and Job's tears. Therefore, thes e prolamins were designated as "alpha-zein-like prolamin" These results sug gest that alleles at the Pro1 locus and those at the Pro2 locus have not ar isen from an identical ancestral gene, and that the Pro2 locus comprise two tightly linked genes, which encode similar prolamins. Hypotheses on the di versification of alleles at the Pro2 locus are discussed based on the N-ter minal amino acid sequences of the respective bands, combinations of bands c ontrolled by the alleles, and frequencies of the alleles.