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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #305117

Research Project: Improved Control of Stripe Rust in Cereal Crops

Location: Wheat Health, Genetics, and Quality Research

Title: Identification of somatic hybridization between Puccinia striiformis f. sp. tritici and P. striiformis f. sp. hordei through virulence and molecular characterization of isolates from wheat, barley and grasses

Author
item CHENG, PENG - Washington State University
item Chen, Xianming
item See, Deven

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2015
Publication Date: 4/1/2016
Citation: Cheng, P., Chen, X., See, D.R. 2016. Identification of somatic hybridization between Puccinia striiformis f. sp. tritici and P. striiformis f. sp. hordei through virulence and molecular characterization of isolates from wheat, barley and grasses. Phytopathology. 106(4):362-371.

Interpretive Summary: The different forms of the stripe rust fungal species can infect wheat, barley and many grass species. Somatic hybridization is a possible mechanism for generating variation in an asexually reproducing population, but evidence is lacking. There are also questions about the possibility of somatic hybridization between the wheat stripe rust pathogen and the barley stripe rust pathogen. This study was undertaken to search for evidence of somatic hybridization through virulence and molecular characterization of natural stripe rust pathogen isolates collected from various grasses as well as wheat and barley. A total of 103 isolates were tested on 20 wheat and 12 barley genotypes that are used to differentiate the wheat and barley stripe rust pathogen forms, respectively, and tested with 20 microsatellite markers. Virulence analyses identified isolates from grasses which were able to infect some differential genotypes of wheat, barley, or both. Simple sequence repeat markers showed that the isolates capable of infecting both wheat and barley are very likely hybrids between the wheat and barley stripe rust pathogen forms. The results indicate that somatic hybridization occurs between the pathogen forms on grasses, especially wild barley grasses which are often infected by both the wheat and barley forms.

Technical Abstract: Puccinia striiformis causes stripe rust on wheat, barley and many grass species. Somatic hybridization is a possible mechanism for generating variation in an asexually reproducing population, but evidence is lacking. There are also questions about the possibility of somatic hybridization between the wheat stripe rust pathogen (P. striiformis f. sp. tritici, Pst) and the barley stripe rust pathogen (P. striiformis f. sp. hordei, Psh). This study was undertaken to search for evidence of somatic hybridization through virulence and molecular characterization of natural isolates collected from various grasses as well as wheat and barley. A total of 103 isolates were tested on 20 wheat and 12 barley genotypes that are used to differentiate Pst and Psh, respectively, and tested with 20 simple sequence repeat (SSR) markers. Virulence analyses identified isolates from grasses which were able to infect some differential genotypes of wheat, barley, or both. SSR markers showed that the isolates capable of infecting both wheat and barley are very likely hybrids between Pst and Psh. The results indicate that somatic hybridization occurs between Pst and Psh on grasses, especially wild barley grasses (Hordeum spp.) which are often infected by both the formae speciales.