Project description:Perennial ryegrass (Lolium perenne L.) is a major grass species used for forage and turf throughout the world, and gains by conventional breeding have reached a plateau. Perennial ryegrass is an outcrossing, self-incompatible diploid (2n = 2x = 14) with a relatively large genome (4067 Mbp/diploid genome; Evans, G.M., Rees, H., Snell, C.L. and Sun, S. (1972). The relation between nuclear DNA amount and the duration of the mitotic cycle. Chrom. Today, 3, 24–31). Using tissues sourced from active pastures during the peak of the autumn, winter, spring and summer seasons, we analysed the ryegrass transcriptome employing a Serial Analysis of Gene Expression (SAGE™) protocol, with the dual goals of understanding the seasonal changes in perennial ryegrass gene expression and enhancing our ability to select genes for genetic manipulation. A total of 159 002 14-mer SAGE™ tags was sequenced and mapped to the perennial ryegrass DNA database, comprising methyl-filtered (GeneThresher®) and expressed sequence tag (EST) sequences. The analysis of 14 559 unique SAGE™ tags, which were present more than once in our SAGE™ library, revealed 964, 1331, 346 and 131 exclusive transcripts to autumn, winter, spring and summer, respectively. Intriguingly, our analysis of the SAGE™ tags revealed season-specific expression profiles for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco), LprbcS. The transcript level for LprbcS was highest in spring, and then decreased gradually between summer and winter. Five different copies of LprbcS were revealed in ryegrass, with one possibly producing splice variant transcripts. Two highly expressed LprbcS genes were reported, one of which was not active in autumn. Another LprbcS gene showed an inverse expression profile to the autumn inactive LprbcS in a manner to compensate the expression level. Keywords: paddock samples, pasture, perennial ryegrass, Serial Analysis of Gene Expression (SAGE™), season specific expression, monocot

Project description:Perennial ryegrass (Lolium perenne L.) is a major grass species used for forage and turf throughout the world, and gains by conventional breeding have reached a plateau. Perennial ryegrass is an outcrossing, self-incompatible diploid (2n = 2x = 14) with a relatively large genome (4067 Mbp/diploid genome; Evans, G.M., Rees, H., Snell, C.L. and Sun, S. (1972). The relation between nuclear DNA amount and the duration of the mitotic cycle. Chrom. Today, 3, 24–31). Using tissues sourced from active pastures during the peak of the autumn, winter, spring and summer seasons, we analysed the ryegrass transcriptome employing a Serial Analysis of Gene Expression (SAGE™) protocol, with the dual goals of understanding the seasonal changes in perennial ryegrass gene expression and enhancing our ability to select genes for genetic manipulation. A total of 159 002 14-mer SAGE™ tags was sequenced and mapped to the perennial ryegrass DNA database, comprising methyl-filtered (GeneThresher®) and expressed sequence tag (EST) sequences. The analysis of 14 559 unique SAGE™ tags, which were present more than once in our SAGE™ library, revealed 964, 1331, 346 and 131 exclusive transcripts to autumn, winter, spring and summer, respectively. Intriguingly, our analysis of the SAGE™ tags revealed season-specific expression profiles for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco), LprbcS. The transcript level for LprbcS was highest in spring, and then decreased gradually between summer and winter. Five different copies of LprbcS were revealed in ryegrass, with one possibly producing splice variant transcripts. Two highly expressed LprbcS genes were reported, one of which was not active in autumn. Another LprbcS gene showed an inverse expression profile to the autumn inactive LprbcS in a manner to compensate the expression level. Keywords: paddock samples, pasture, perennial ryegrass, Serial Analysis of Gene Expression (SAGE™), season specific expression, monocot Ryegrass tissue Perennial ryegrass (Lolium perenne L.) cv. Bronsyn was used throughout this study. Field-grown samples, comprising mainly viable leaves and pseudostems, were collected at midday from livestock-active monocultural paddocks at Dexcel, Hamilton, New Zealand during the peak of each season, and frozen immediately in liquid nitrogen. Samples were transported in dry-ice and stored at ?80 oC until use. During spring and summer, care was taken not to include any floral stems in the tissue sample. Grass samples were collected from pregrazed (15–60 days post-grazing) and post-grazed (1 day post-grazing) ryegrass swards, which were visibly healthy and free of any pests. Construction of SAGE™ libraries RNA was extracted using TRIZOL® reagent (Invitrogen, Carlsbad,CA, USA). For each SAGE™ library, 100 ug of pre- and post-grazed sample-derived total RNA was employed, and the libraries were created using an I-SAGE™ or I-SAGE™Long Kit (Invitrogen) according to the manufacturer’s protocol. Pre- and post-grazed SAGE™ libraries were sequenced at the Australian Genome Research Facility (Brisbane, Australia), and the tags were extracted using SAGE2000 software and combined to produce the transcript profile for the season.

Project description:This study compared the photosynthetic performance and the global gene expression of the winter hardy wheat Triticum aestivum cv Norstar grown under non-acclimated (NA) or cold-acclimated (CA) condition at either ambient CO2 or elevated CO2 (EC). CA Norstar maintained comparable light saturated and CO2 saturated rates of photosynthesis but lower quantum requirements for photosystem II and non photochemical quenching relative to NA plants even at EC. Neither NA nor CA plants were sensitive to feedback inhibition of photosynthesis at EC. Global gene expression using microarray combined with bioinformatics analysis revealed that genes affected by EC were 3 times higher in NA (1022 genes) compared to CA (372 genes) Norstar. The most striking effect was the down-regulation of genes involved in the plant defense responses in NA Norstar. In contrast, cold acclimation reversed this down regulation due to the cold induction of genes involved in plant pathogenesis resistance, and cellular and chloroplast protection. These results suggest that EC have less impact on plant performance and productivity in cold adapted winter hardy plants in the northern climates compared to warmer environments. Selection for cereal cultivars with constitutively higher expression of biotic stress defense genes may be necessary under EC during the warm growth period and in warmer climates. Twelve replicate pots with 3 plants per pot were grown at either NA or CA conditions at either ambient or EC. To minimize any possible chamber effects, the 12 replicate pots at each growth condition were distributed between two growth chambers. A total of 3 biological replicates for each condition were used for microarray analyses. Each biological replicate sample was obtained by pooling three whole fully expanded 3rd leaves from different plants harvested randomly. The different biological samples of Norstar winter wheat leaves were ground in dry ice to fine powder and total RNA was extracted with trizol (Invitrogen, Burlington, ON, CA). Total RNA was cleaned using RNeasy plant mini kit (Qiagen) and integrity was determined on agarose gel and on a bioanalyser (Agilent 2100). Synthesized cDNAs were transcribed to cRNAs with the 3M-bM-^@M-^YIVT labelling kit (Santa Clara, CA, USA) and hybridized to the Affymetrix wheat genome array (Santa Clara, Ca, USA) at the McGill University and GM-CM-)nome QuM-CM-)bec Innovation Centre (Montreal, Qc, CA). The experimental design consisted of three biological replicates for each of the four growth conditions, 1: Non-acclimated (NA) at ambient CO2 (AC) (NAAC); 2: Cold-acclimated (CA) at ambient CO2 (AC) (CAAC); 3: Non-acclimated (NA) at elevated CO2 (EC) (NAEC); 4: Cold-acclimated (CA) at elevated CO2 (EC) (CAEC). Thus, a total of 3 biological samples from each of the 4 growth conditions described above were used for hybridizations.

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Global transcriptome changes in perennial ryegrass during early infection by pink snow mould

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