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

The level and type of resistance against leaf rust (Puccinia hordei) was de termined in modern spring barley germplasm. In field trials all over Europe most accessions were in some locations and years significantly less infect ed than the moderately resistant reference 'Grit'. Differentiating P, horde i isolates indicated that most accessions carried hypersensitivity (Rph) ge nes. A virulence survey indicated that among the known resistance genes, on ly Rph7 is still fully effective in Europe. Some accessions carried undeter mined hypersensitivity resistance gene(s) that were effective to all isolat es tested. The level of non-hypersensitivity or partial resistance was asse ssed from the latency period of the fungus and the percentage of early abor ted infection units not associated with plant cell necrosis. These paramete rs indicated that several accessions had a level of partial resistance high er than that of the highly partially resistant 'Vada'. We concluded that ba rley breeders have achieved very high levels of partial resistance against P. hordei in spring barley germplasm.