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Abstract Detail

Poster Session

Bailey, Jordan [1], Karaoglu, Haydar [2], Wellings, Colin [2], Park, Robery [2].

Development of diagnostic molecular markers for Puccinia striiformis f. sp. tritici..

Puccinia striiformis f. sp. tritici (Pst) is a specialized form (forma specialis; f. sp.) of the stripe rust pathogen which infects wheat. It was first detected in Australia in 1979 (Pst-104 pathotype lineage) with subsequent f. sp. incursions in 1997 (P. striiformis f. sp. pseudohordei (Psp-h) on wild barley grass) and 2002 (Pst-134 pathotype lineage). The threat of further incursions of exotic isolates in this pathogen group especially exotic barley stripe rust (P. striiformis f. sp. hordei (Psh)) and new lineages of Pst, continues to be a concern to the cereals industries. Due to the clonal nature of many Pst populations, highly polymorphic co-dominant molecular markers such as simple sequence repeats (SSRs) are needed to study pathogen variability and to rapidly identify incursions of exotic genotypes. Three draft genome sequences for Pst were surveyed individually for abundance and class of SSR motif. In total, 1,889 SSR loci were identified and 806 primer pairs were designed and screened using seven Puccinia species and representative forma speciales. SSR polymorphisms generated by 70 primer pairs were further evaluated using additional isolates of Pst and known or suspected f. spp. of P. striiformis. Twenty-five polymorphic SSR markers that were specific for selective and sensitive amplification of Pst isolates were identified, these generated allelic diversity ranges from 2 to 8 alleles per locus and polymorphic information content (PIC) values from 0.5 to 0.76 with an average of 0.54. The 25 published SSR markers will have direct application in studies associated with population genetics of Pst, and in improving the efficacy of diagnostic assays critical for incursion management of exotic forms of P. striiformis. Diagnostic tools that allow rapid and efficient pathogen identification are needed to minimise risk and time constraints associated with initial incursion management. In a continuation of the markers published above, nine SSR markers were further developed and evaluated for their application in diagnostics of stripe rust isolates from both asexual urediniospores and rust infected leaf tissue. The markers are able to differentiate the three forms of P. striiformis (Pst, Psh and Psp-h) as well as the two major pathotype lineages in Australia, and related stripe rust pathogens P. striiformoides (cocksfoot stripe rust (Psds)) and P. pseudostriiformis (Kentucky bluegrass stripe rust (Pps)). Target PCR products are amplified even when applied to minute and degraded DNA samples and the primers are robust, reproducible, and products can be visualized on 3% agarose gel electrophoresis.

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1 - Purdue University, Botany and Plant Pathology, 915 W. State St, Lilly Hall of Sciences, West Lafayette, IN, 47907, United States
2 - Sydney University, Agriculture and the Environment, 107 Cobbitty rd, Cobbitty, Sydney, NSW, 2507, Australia

Stripe rust

Presentation Type: Offered Paper - Poster
Session: P1
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 8:00 PM
Number: P1008
Abstract ID:136
Candidate for Awards:None

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