Project description:Stem rust of wheat is a deleterious fungal disease across the globe causing severe yield losses. Although, many stem rust resistance genes (Sr) are being used in wheat breeding programs, new emerging stem rust pathotypes are a challenge to important Sr genes. In recent years, multiple studies on leaf and yellow rust molecular mechanism have been done, however, for stem rust such studies are lacking. Current study investigated stem rust induced response in the susceptible wheat genotype C306 and its Near Isogenic Line (NIL) for Sr24 gene, HW2004, using microarray analysis to understand the transcriptomic differences at different stages of infection. Results showed that HW2004 has higher basal levels of several important genes involved in pathogen detection, defence, and display early activation of multiple defence mechanisms. Further Gene Ontology (GO) and pathway analysis identified important genes responsible for pathogen detection, downstream signalling cascades and transcription factors (TFs) involved in activation and mediation of defence responses. Results suggest that generation of Reactive Oxygen Species (ROS), cytoskeletal rearrangement, activation of multiple hydrolases, and lipid metabolism mediated biosynthesis of certain secondary metabolites are collectively involved in Sr24-mediated defence in HW2004, in response to stem rust infection. Novel and unannotated, but highly responsive genes were also identified, which may also contribute towards resistance phenotype. Furthermore, certain DEGs also mapped close to the Sr24-linked marker on Thinopyrum elongatum translocated fragment on wheat 3E chromosome, which advocate further investigations for better insights of the Sr24-mediated stem rust resistance.
Project description:Aim:To characterise a recently discovered stem rust resistance locus on wheat chromosome 7AL. Transcriptome analysis by RNA-sequencing, in association with microscopic observations, was used to compare responses to the Puccinia graminis f. sp. tritici pathogen of the susceptible line Columbus, and two independent backcrossed resistant lines containing the locus, Columbus-NS765 and Columbus-NS766. Results: Microscopic observations of infected leaves revealed that the resistance conferred by the 7AL resistance locus was initiated by two days post-inoculation, upon the entry of the stem rust fungus into the plant through the stoma. Death of guard and epidermal cells adjacent to the fungal points of entry was observed to be clearly more frequent in resistant lines than in the susceptible genotype, suggesting that the resistance response is similar in all genotypes, but enhanced in the resistant lines. Transcriptomic analysis, combined with assignment of genes to wheat chromosomes, revealed a disporportionately high number of differentially expressed genes were located on chromosomes 7AL and 6A. A number of genes annotated as cysteine-rich receptor-like kinases were located on chromosome 7AL. Closer investigation indicated that the encoded proteins were in fact putative receptor-like cytoplasmic kinases (RLCKs). One of the putative RLCK genes contained a SNP marker previously shown to co-segregate with the 7AL resistance locus. The large number of differentially expressed genes on chromosome 6A indicated the presence of a large introgression on this chromosome that co-segregated with stem rust resistance in the two independent resistant lines, but its role in the resistance response is currently unclear. Conclusions: This study represents the first transcriptome analysis of responses to stem rust in wheat, and the first investigation of the resistance conferred by the newly-discovered wheat 7AL stem rust resistance locus. Microscopy showed the resistance response was associated with pre-haustorial cell death. Results of the RNA-seq, which has the resolution to discriminate between homeologous wheat genes, along with assignment of differentially expressed genes to wheat chromosomes, suggested putative receptor-like cytoplasmic kinases linked to the 7AL locus as candidate resistance genes for further investigation.
Project description:Transcriptional changes were monitored in the wheat cultivar Avocet*6/Yr1 following inoculation with avirulent and virulent wheat yellow rust (Puccinia striiformis f.sp. tritici) isolates using the Affymetrix wheat genome array GeneChip®. Seedlings of Avocet*6/Yr1 were grown to growth stage 12-13 (Zadoks et al., 1974) before inoculating with either the P.s. f.sp. tritici isolate 169E136 (Yr1-virulent) or 232E137 (Yr1-avirulent) or with talc for the Mock inoculation (Boyd and Minchin 2001). Plants were grown under a 16/8 hour photoperiod cycle, supplemented with sodium lighting (240 ?mol m-2 s-1) at day/night temperatures of 20°C/15°C and a relative humidity of 60%, both before and after inoculation, in a spore-free, containment level 2 greenhouse. Leaf samples from six seedlings were collected 6, 12, 24, 48 and 72 hpi for RNA extraction and transcriptomics analysis from three independent biological experiments. Leaf tissue was ground under liquid nitrogen and total RNA extracted using the TRIzol reagent method, following the manufacturer’s instructions (Invitrogen, Carlsbad, CA). RNA from each time point (16 ?g) were pooled to obtain 80 ?g of total RNA for each treatment (mock inoculated control; avirulent isolate inoculated; virulent isolate inoculated). Pooled RNA samples were further purified using the Qiagen RNeasy mini-kit according to the manufacturer instructions (Qiagen) and RNA integrity was confirmed using the Agilent 2100 Bioanalyzer (Agilent). Affymetrix GeneChip processing, including RNA quality control, microarray hybridisation and data acquisition was performed through contract research services by the John Innes Genome Laboratory, John Innes Centre, Norwich, U.K. A total of nine hybridisations were performed. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Osman Bozkurt. The equivalent experiment is TA25 at PLEXdb.] pathogen isolates: Mock inoculated (Control)(3-replications); pathogen isolates: Yr1-avirulent wheat yellow rust isolate 232E137(3-replications); pathogen isolates: Yr1-virulent wheat yellow rust isolate 169E136(3-replications)
Project description:Fusarium graminearum causes Fusarium head blight (FHB), which represents one of the major wheat diseases worldwide, determining reduction in grain quality, yield and the accumulation of mycotoxins. To mine the molecular response associated to the wheat 2DL FHB resistance quantitative trait locus (QTL), derived from the cultivar Wuhan-1, and to identify candidate genes implicated in such resistance, a comprehensive transcriptomic analysis of the early response to F. graminearum infection at 3 days post inoculation of spikelet and rachis was performed with the RNA-Seq and miRNA-Seq techniques. The analyses were conducted on two Near Isogenic Lines (NILs) differing for the presence of the 2DL QTL (2-2618, resistant 2DL+ and 2-2890, susceptible null).
Project description:The RNA sequencing analysis was undertaken to investigate the transcriptomic changes in adult wheat inoculated with Puccinia graminis f. sp. tritici the causal agent of stem rust disease. The project firstly aims to compare gene expression in one susceptible wheat line with two wheat lines exhibiting adult plant resistance to the stem rust. Secondly, the project aims to examine the temporal changes in gene expression in wheat after inoculation. Wheat plants was grown until maturity under greenhouse conditions. Plants were inoculated with Puccinia graminis f. sp. tritici and the flag leaf sheath sampled for RNA sequencing. The project aims to give essential insight into the adult plant resistance response in wheat to Puccinia graminis f. sp. tritici inoculation.
Project description:Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a destructive disease of wheat worldwide. Genetic resistance is the preferred method for controlling stripe rust, of which two major types are race-specific and race non-specific resistance. Race-specific resistance includes the qualitatively inherited all-stage resistance, controlled by single major resistance (R) genes. Conversely, adult-plant resistance is race non-specific, inherited quantitatively, and is durable. Previously, we characterized the gene expression signatures involved in Yr5-controlled all-stage resistance and Yr39-controlled adult-plant resistance using the Affymetrix Wheat GeneChip. For this study, we designed and constructed custom oligonucleotide microarrays containing probes for the 116 and 207 transcripts that we had found important for the Yr5 and Yr39 resistance responses, respectively. We used this custom microarray to profile the resistance responses of eight wheat genotypes with all-stage resistance (Yr1, Yr5, Yr7, Yr8, Yr9, Yr10, Yr15, and Yr17). The aim of this analysis was to identify common and unique gene expression signatures involved in race-specific resistance accross genotypes, which were used to infer information regarding the general pathways involved in all-stage resistance. Keywords: Stress response
Project description:Two sets of wheat lines near-isogenic to Lr34 were used to compare gene expression profiles of wheat: 1. with and without Lr34 gene; 2. rust and mock inoculation; 3. distal and basal portion of the flag leaves. The two sets of wheat near-isogenic lines were used to subtract genetic background variations and to enrich Lr34-regulated gene expression profiles. The study is aimed to better understand the mechanisms of the well-known durable leaf rust resistance gene, Lr34, mediated resistance at the transcriptome level. Keywords: Distal and basal leaf halves of near-isogenic lines
Project description:Two sets of wheat lines near-isogenic to Lr34 were used to compare gene expression profiles of wheat: 1. with and without Lr34 gene; 2. rust and mock inoculation; 3. distal and basal portion of the flag leaves. The two sets of wheat near-isogenic lines were used to subtract genetic background variations and to enrich Lr34-regulated gene expression profiles. The study is aimed to better understand the mechanisms of the well-known durable leaf rust resistance gene, Lr34, mediated resistance at the transcriptome level. Experiment Overall Design: Wheat near-isogenic lines, Jupateco with Lr34 (JUR), Jupateco without Lr34 (JUS), Thatcher with Lr34 (THR), and Thatcher without Lr34 (THS) were used. Thatcher lines were rust (I) or mock (M) inoculated. Jupateco lines were mock inoculated. Distal (T) and basal (B) half of the leaves were harvested and processed separately. Three biological replications were applied to each treatment.
Project description:The wheat gene Lr34 confers partial resistance to all races of Puccinia triticina, the causal agent of wheat leaf rust. However, the biological basis for the exceptional durability of Lr34 is unclear. The Affymetrix wheat genome array was used to identify wheat genes differentially expressed in a compatible interaction (Tc), an R-gene mediated incompatible interaction (Tc-Lr1), and a race non-specific resistance interaction (Tc-Lr34) in response to infection challenge by P. triticina race 1 at anthesis. Transcriptome interrogation was conducted by comparing mock- and P. triticina-inoculated leaves harvested at 3 and 7 days post inoculation (dpi). SUBMITTER_CITATION: Bolton, M.D., Kolmer, J.A., Xu, W.W., and Garvin, D.F. 2008. Lr34-mediated leaf rust resistance in wheat: transcript profiling reveals a high energetic demand supported by transient recruitment of multiple metabolic pathways. Molecular Plant-Microbe Interactions 21:1515-1527. Experiment Overall Design: The Affymetrix wheat genome array was used to identify wheat genes differentially expressed in a compatible interaction (Tc), an R-gene mediated incompatible interaction (Tc-Lr1), and a race non-specific resistance interaction (Tc-Lr34) in response to infection challenge by P. triticina race 1 at anthesis. Transcriptome interrogation was conducted on leaves harvested at 3 and 7 days post inoculation (dpi). The study utilized a randomized complete block design with three replicates for each genotype, and employed univariate analysis (t-tests) between mock- and P. triticina-inoculated plants within each genotype at each timepoint, for a total of six comparisons across the entire experiment, utilizing a total 36 Affymetrix Wheat Genome Array GeneChips.
Project description:The wheat gene Lr34 confers partial resistance to all races of Puccinia triticina, the causal agent of wheat leaf rust. However, the biological basis for the exceptional durability of Lr34 is unclear. The Affymetrix wheat genome array was used to identify wheat genes differentially expressed in a compatible interaction (Tc), an R-gene mediated incompatible interaction (Tc-Lr1), and a race non-specific resistance interaction (Tc-Lr34) in response to infection challenge by P. triticina race 1 at anthesis. Transcriptome interrogation was conducted by comparing mock- and P. triticina-inoculated leaves harvested at 3 and 7 days post inoculation (dpi). Keywords: Time course