VARIABILITY AMONG MEMBERS OF THE HOR-2 MULTIGENE FAMILY

The hordeins comprise the major prolamin storage proteins of barley. T wo major and one minor gene families encode these alcohol-soluble prot eins. The Hor-2 gene family encoding the B-hordeins has been estimated to contain 15-30 copies. Although several genes encoding B-hordeins h ave been cloned and sequenced, little is known about the mechanisms re sponsible for the generation of the enormous genetic variability at th is locus. Polymerase chain reaction sequence amplification provided a simple technique that permitted the amplification of the Hor-2 gene fa mily members from the genomes of several barley genotypes. Sequence an alysis of clones permitted the identification of a region within the H or-2 structural gene that appears to undergo recombinational and slipp age-like gene conversion events. In this report we describe variabilit y of the B-hordein genes, possible mechanisms responsible for it, and implications this may have on the evolution of prolamin-encoding gene families.