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Title: Transcriptome analysis of high-temperature adult-plant resistance conditioned by Yr39 during the wheat-Puccinia striiformis f. sp. tritici interaction

Author
item Coram, Tristan
item SETTLES, MATTHEW - WASHINGTON STATE UNIV
item Chen, Xianming

Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2007
Publication Date: 4/1/2008
Citation: Coram, T., Settles, M.L., Chen, X. 2008. Transcriptome analysis of high-temperature adult-plant resistance conditioned by Yr39 during the wheat-Puccinia striiformis f. sp. tritici interaction. MPP 9:479-493.

Interpretive Summary: Stripe rust is a destructive disease of wheat worldwide. The Alpowa spring wheat cultivar has durable, non-race specific high-temperature adult-plant (HTAP) resistance to stripe rust durable. To identify transcripts (expressed genes) associated with the HTAP resistance, we selected two lines from the Avocet S/Alpowa cross that differed at the resistance gene locus to represent an incompatible and compatible interaction with the wheat stripe rust pathogen. Using the microarray technique, we profiled the transcript changes occurring in flag leaves of these two lines over a time-course after treatment with stripe rust and no-rust treatment. This time-course study identified 99 induced transcripts that were classified as HTAP resistance-specific. The temporal pattern of transcript accumulation showed a peak at 48 h after infection, which was supported by microscopic observation of fungal development and quantitative PCR assays that showed a rapid increase in fungal biomass after this time in the compatible interaction. More than half of the annotated transcripts specifically induced during HTAP resistance were involved in defense and/or signal transduction, including resistance gene homologues and transcripts associated with pathogenesis-related protein production, syntheses of plant defense gene products, and protein kinase signaling. This study represents the first transcript profiling of HTAP resistance to stripe rust in wheat. Comparison of results of the race non-specific resistance in this study and those of our previous studies on race-specific revealed molecular mechanisms of wheat resistance to stripe rust.

Technical Abstract: Stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici Eriks. (Pst)) is a destructive disease of wheat (Triticum aestivum L.) worldwide. High-temperature adult-plant resistance (HTAP) to stripe rust is race non-specific, inherited quantitatively, and durable. Previously, we identified and mapped the single Yr39 HTAP stripe rust resistance gene in the spring wheat cultivar Alpowa, which was identified on chromosome 7BL and accounted for 64.2% of the variation in HTAP resistance. To identify transcripts associated with Yr39-mediated HTAP resistance, we selected two recombinant inbred lines (RILs) from an ‘Avocet S/Alpowa’ cross that differed at the Yr39 locus to represent an incompatible (Yr39) and compatible (yr39) interaction with Pst. Using the Affymetrix Wheat GeneChip, we profiled the transcript changes occurring in flag leaves of these two RILs over a time-course after treatment with Pst urediniospores and mock-inoculation. This time-course study identified 99 induced transcripts that were classified as HTAP resistance-specific. The temporal pattern of transcript accumulation showed a peak at 48 h after infection, which was supported by microscopic observation of fungal development and quantitative PCR assays that showed a rapid increase in fungal biomass after this time in the compatible interaction. More than half (50.5%) of the annotated transcripts specifically induced during HTAP resistance were involved in defense and/or signal transduction, including R gene homologues and transcripts associated with pathogenesis-related protein production, phenylpropanoid biosynthesis, and protein kinase signaling. This study represents the first transcript profiling of HTAP resistance to stripe rust in wheat, and we compare our results to other transcript studies of race-specific and race non-specific resistance.