BACKGROUND: The barley-Puccinia hordei (barley leaf rust) pathosystem is a model for investigating partial disease resistance in crop plants and genetic mapping of phenotypic resistance has identified several quantitative trait loci (QTL) for partial resistance. Reciprocal QTL-specific near-isogenic lines (QTL-NILs) have been developed that combine two QTL, Rphq2 and Rphq3, the largest effects detected in a recombinant-inbred-line (RIL) population derived from a cross between the super-susceptib ...[more]
Project description:Positional gene isolation requires either a local or global reference genome sequence or an inference of gene content based on conservation of synteny with a genomic model. In the large unsequenced genomes of the Triticeae cereals the latter, i.e. conservation of synteny with the rice and Brachypodium genomes, provides a powerful proxy for establishing local gene content and order. However, exploiting conservation of synteny requires 'homology bridges' between the model genome and the target region that contains a gene of interest. As effective homology bridges are generally the sequences of genetically mapped genes, increasing the density of mapped these genes around a target locus is an important step in the process. We used Bbulked Ssegregantte Aanalysis (BSA) of transcript abundance data to identify genes located in a specific region of the barley genome. The approach is valuable because only a relatively small proportion of barley genes are currently placed on a genetic map. We analyzed eQTL datasets from the reference Steptoe x Morex doubled haploid population and showed a strong association between differential gene expression and cis-regulation, with 83% of differentially expressed genes co-locating with their eQTL. We then performed bulked segregant analysis (BSA) by assembling allele-specific bulks pools based on the genotypes of individuals at the partial resistance QTL Rphq11. BSA identified a total of 411 genes as differentially expressed, including HvPHGPx, that was previously identified as being a promising candidate for Rphq11. The genetic location of 276 of these genes could be determined from both eQTL datasets and conservation of synteny, and 254 (92%) of these were located on the target chromosome. We conclude that identification of differential expression by BSA constitutes a novel method to identify genes located in specific regions of interest. The datasets obtained from such studies provide a high-profile repertoirerobust set of candidate genes for analysis and serve as valuable resources for targeted marker development and comparative mapping with other grass species.
Project description:In this experiment the transcriptome reprogramming in wheat during host and nonhost interaction with Puccinia sp. was analyzed in a time-series approach. Ten days old wheat plants of cv. Renan were mock-inoculated or inoculated with P. triticina (Pt), BRW96258 isolate, or P. hordei (Ph), 1.2.1 isolate. After 12, 24, 36 and 48 hours first leaves were sampled. Total RNA was extracted using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany), the Ambion TURBO DNA-free DNase Kit was used for DNA elimination, and RNA was hybridized to Agilent 44k oligonucleotide arrays.
Project description:In this experiment the transcriptome reprogramming in barley during host and nonhost interaction with Puccinia sp. was analyzed in a time-series approach. Ten days old barley plants of cv. Vada were mock-inoculated or inoculated with P. hordei (Ph), 1.2.1 isolate, or P. triticina (Pt), BRW96258 isolate. After 12, 24, 36 and 48 hours first leaves were sampled. Total RNA was extracted using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany), the Ambion TURBO DNA-free DNase Kit was used for DNA elimination, and RNA was hybridized to Agilent 44k oligonucleotide arrays.
Project description:Powdery mildew is a very common plant disease and only few plants are immune. Host interactions have been identified and characterized for the pathosystems barley-B. graminis f. sp. tritici (Bgt) and wheat-B. graminis f. sp. hordei (Bgh), whereas no data are reported about powdery mildew and nonhost plants, such as rice. On the other hand rice nonhost resistance is widely unexploited and only few expression data are available. To characterize rice response during nonhost interaction with Bgh, a global expression analysis was performed by using the GeneChip® Rice Genome Array. To describe rice gene expression profiles during nonhost interaction, 2 week-old rice plantlets were inoculated with Bgh. Treated (inoculated) and control (mock) samples were collected 24 hours post-inoculation for GeneChip® Rice Genome Array hybridization. For transcript proﬁling experiments with powdery mildew, entire leaves were sampled from rice plantlets 2 weeks old (cv. Nipponbare). Treated and control (mock) rice leaves were collected 24 hours post inoculation. Three biological replicates for inoculated and control plants were extracted and analysed independently with the GeneChip® Rice Genome Array.
Project description:Puccinia graminis f. sp. tritici is the cause of wheat stem rust. A microarray was designed from genes predicted from the P. graminis f. sp. tritici genome assembly, and gene expression measured for four conditions which include wheat or barley infecting growth stages initiated by urediniospores. mRNA was prepared from fresh urediniospores, uredinospores germinated for 24 hr, wheat seedlings infected with urediniospores for 8 days, and barley seedlings infected with urediniospores for 8 days. The asexual uredinial infection cycle on wheat produces additional urediniospores, which can start new cycles of wheat infection and are readily spread by aerial transport. This expression data is further described in Duplessis et al, Obligate Biotrophy Features Unraveled by the Genomic Analysis of the Rust Fungi, Melampsora larici-populina and Puccinia graminis f. sp. tritici Overall design: A total of 12 samples were analyzed, including three biological replicates of the four conditions.