RFLP mapping of a gene for hairy leaf sheath using a recombinant line fromHordeum vulgare L. x Hordeum bulbosum L. cross

A gene conditioning hairy leaf sheath character, which was derived from Hor deum bulbosum and designated Hs(b), was mapped using a cross between Hordeu m vulgare and a H. vulgare/H. bulbosum recombinant line. The Hs(b) locus wa s tagged relative to eight RFLP markers detecting three loci on the distal part of chromosome 4HL. The map position suggests that Hs(b) of H. bulbosum is homoeologous to the gene Hp1 of rye (Secale cereale), which pleiotropic ally governs the traits hairy leaf sheath and hairy peduncle. It is propose d that the recombination break point between H. vulgare and H. bulbosum chr omosomes occured at a position homoeologous compared with the 4L/5L translo cation in Triticeae genomes, and may reflect a hot spot for chromosome brea kage.