Net blotch resistance in wild species of Hordeum

Resistance to net blotch was evaluated in 175 Hordeum vulgare subsp. spontaneum (H. spontaneum) accessions and 149 accessions of thirteen species or subspecies of wild Hordeum. Most H. spontaneum accessions showed resistance to each of the four Pyrenophora teres f. teres (P. teres) isolates tested. However, H. spontaneum accessions showed different resistance reactions, depending upon their origin. In particular, some accessions from Afghanistan and Russia showed a high level of resistance, and accessions from Morocco were susceptible. Among the four P. teres isolates, the virulence spectra on the H. spontaneum accessions were more different between isolates from different countries than between those from the same country. Hordeum spontaneum accessions susceptible to the Canadian isolate WRS102, but resistant to the other three isolates were found in Iraq suggesting the geographical differentiation of resistance genes in H. spontaneum. All accessions of the other wild Hordeum species, especially some accessions of H. marinum subsp. gussoneanum, showed high levels of resistance. These resistance genes may be useful candidates for incorporation into cultivated barley. This revised version was published online in July 2006 with corrections to the Cover Date.