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Genetic and Molecular Mapping of Stripe Rust Resistance Gene in Wheat–Psathyrostachys huashanica Translocation Line H9020-1-6-8-3

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat worldwide. The best strategy to control stripe rust is to grow resistant cultivars, but only a few effective genes are available. The wheat accession H9020-1-6-8-3 is a translocation line previously developed from interspecific hybridization between wheat genotype 7182 and Psathyrostachys huashanica, and is resistant to most Chinese Puccinia striiformis f. sp. tritici races. To identify the resistance genes in the translocation line, H9020-1-6-8-3 was crossed with susceptible genotype Mingxian 169, and seedlings of parents and F₁, F₂, and F₃ progenies were tested with prevalent Chinese P. striiformis f. sp. tritici races CYR32 and CYR33 under controlled greenhouse conditions. The genetic results indicated that two single dominant genes in H9020-1-6-8-3 confer resistance to CYR32 and CYR33, respectively. The gene for resistance to CYR33 was temporarily designated as YrH9020. Six simple-sequence repeat markers were used to map the resistance gene to the short arm of wheat chromosome 2D, using 329 F₂ plants tested with CYR33 in the greenhouse. The genetic distances of the two closest flanking markers, Xgwm261 and Xgwm455, were 4.4 and 5.8 centimorgans, respectively. Disease assessments and polymorphic tests of the flanking markers among the Psathyrostachys huashanica line and wheat lines 7182, H9020-1-6-8-3, and Mingxian169 suggested that the resistance gene YrH9020 in H9020-1-6-8-3 was originally from P. huashanica. The exotic stripe rust resistance gene and linked molecular markers should be useful for pyramiding with other genes to develop wheat cultivars with high-level and durable resistance to stripe rust.