Resistance of Wild Barley Accessions from Israel to Leaf Rust Collected in the USA and Israel1

Abstract

Wild barley (Hordeum spontaneum C. Koch) is being used to develop improved barley (H. vulgare L.) cultivars. It is a source of genes for resistance against leaf rust (Puccinia hordei Otth) but the evaluation of this source has been done at only a few locations, and to a narrow range of the virulence available. In this study, accessions of wild barley that had been exposed over a 10‐yr period to numerous isolates of leaf rust indigenous in Israel, were reevaluated for resistance in glasshouse and field trials in Israel and the USA to 11 isolates of leaf rust that varied greatly in virulence and origin. Reactions of seedlings confirmed that resistance to leaf rust is common in wild barley. Twelve accessions were resistant or contained plants that were resistant to all the pathogen isolates tested at each location. At St. Paul, MN, accession reactions in the glasshouse and the field were generally similar. At Bet Dagan, Israel, resistance was recognized in the field by low infection types to the rust as well as by slow rusting. Some lines were fully resistant in the USA, but they rusted slowly in Israel. All accessions from dry parts of Israel were susceptible to all isolates of the pathogen probably because they have never been infected with the pathogen. The accessions studied and the methods of study may be useful for indepth work on host‐parasite evolution, especially the incompatible relationships.