Barley nurseries comprising 820 lines with 479 unique pedigrees sourced from the International Centre for Agricultural Research in the Dry Areas (ICARDA) were screened for seedling and adult plant resistance (APR) against Australian isolates of barley leaf rust pathogen Puccinia hordei Otth. Ninety three percent of the lines were postulated to carry the seedling leaf rust resistance gene Rph3 based on their susceptibility in the greenhouse and field against Rph3 virulent pathotype and resistance to Rph3 avirulent pathotypes. The remaining lines showed either presence of uncharacterised seedling resistance (1%) and uncharacterised APR (1%). Five percent of lines were susceptible at both seedling and adult plant growth stages. Of the six lines identified to carry uncharacterised APR, three likely carried Rph20 based on the presence of the Rph20-linked marker bPb-0837. The results suggested that most of the ICARDA germplasm tested is not suitable for leaf rust resistance in Australia due to the presence of virulence for Rph3. Lines carrying uncharacterised seedling resistance and APR are potentially new sources of resistance, and are recommended for genetic analysis.
Key words: Hordeum vulgare, Puccinia hordei, adult plant resistance, Rph3.
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