Resistance against barley leaf rust (Puccinia hordei) in West-European spring barley germplasm

Abstract

The level and type of resistance against leaf rust (Puccinia hordei) was determined in modern spring barley germplasm. In field trials all over Europe most accessions were in some locations and years significantly less infected than the moderately resistant reference 'Grit'. Differentiating P. hordei isolates indicated that most accessions carried hypersensitivity (Rph) genes. A virulence survey indicated that among the known resistance genes, only Rph7 is still fully effective in Europe. Some accessions carried undetermined hypersensitivity resistance gene(s) that were effective to all isolates tested. The level of non-hypersensitivity or partial resistance was assessed from the latency period of the fungus and the percentage of early aborted infection units not associated with plant cell necrosis. These parameters indi- cated that several accessions had a level of partial resistance higher than that of the highly partially resistant 'Vada'. We concluded that barley breeders have achieved very high levels of partial resistance against P. hordei in spring barley germplasm. barley / leaf rust / partial resistance / virulence / hypersensitivity Resume - Resistance a la rouille brune ( Puccinia hordei) du germplasme d'orge de printemps d'Europe de l'ouest. Le niveau et le type de resistance contre la rouille brune (Puccinia hordei) ont ete determine chez le germplas- me d'orge de printemps. Dans des champs experimentaux presents dans l'Europe entiere, la plupart des accessions ont ete pour certains sites et annees, moins infectees compare a la reference 'Grit' qui est moderement resistante. Des iso- lats de P. hordei differencies ont indique que la plupart des accessions contenaient les genes d'hypersensitivite Rph. Un test de virulence a indique que des genes Rph connus, seul Rph7 est encore completement efficace en Europe. Certaines