24 research outputs found
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Life cycle expression analysis of three cell wall degradation-related genes in ethylene-treated grass
Ethylene regulates multiple developmental processes during a plant life cycle, but the effect of ethylene on the upregulation of senescence-, stress-, and post-harvest-related genes in forage grasses is poorly understood. In this work, we used quantitative PCR to determine whether ethylene application affected the expression of selected cell-wall degradation related genes that are typically upregulated post-harvest. The expression levels of beta-D-glucan exohydrolase isoenzyme, alpha glucosidase, and arabinoxylan arabinofuranohydrolase isoenzyme, all putative cell wall degrading enzymes, were quantified at six points in the life cycle of the model grass species Darnel ryegrass (Lolium temulentum L.). We also quantified the expression of ACC oxidase and ACC synthase in response to ethylene application to determine if endogenous upregulation of ethylene biosynthesis occurred. Grass developmental stage had a significant impact on gene expression response to ethylene-treatment, indicating that discrete life cycle stages present different ethylene-responsive windows for treatment. Under our experimental conditions, ACC oxidase and ACC synthase expression were downregulated in response to ethylene-treatment, suggesting that exogenous ethylene served an auto-inhibitory role. Transcripts corresponding to the three cell wall degradation related genes increased significantly in response to ethylene treatment, suggesting that ethylene may have future utility in the pretreatment of lignocellulosic biomass. To our knowledge, this is the first report of a life cycle analysis of ethylene-induced genes in forage grasses.Keywords: Cell wall, Ethylene, Darnel ryegrass, RT-qPCR, Lolium temulentu
An improved, high-quality draft genome sequence of the Germination-Arrest Factor-producing Pseudomonas fluorescens WH6
<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas fluorescens </it>is a genetically and physiologically diverse species of bacteria present in many habitats and in association with plants. This species of bacteria produces a large array of secondary metabolites with potential as natural products. <it>P. fluorescens </it>isolate WH6 produces Germination-Arrest Factor (GAF), a predicted small peptide or amino acid analog with herbicidal activity that specifically inhibits germination of seeds of graminaceous species.</p> <p>Results</p> <p>We used a hybrid next-generation sequencing approach to develop a high-quality draft genome sequence for <it>P. fluorescens </it>WH6. We employed automated, manual, and experimental methods to further improve the draft genome sequence. From this assembly of 6.27 megabases, we predicted 5876 genes, of which 3115 were core to <it>P. fluorescens </it>and 1567 were unique to WH6. Comparative genomic studies of WH6 revealed high similarity in synteny and orthology of genes with <it>P. fluorescens </it>SBW25. A phylogenomic study also placed WH6 in the same lineage as SBW25. In a previous non-saturating mutagenesis screen we identified two genes necessary for GAF activity in WH6. Mapping of their flanking sequences revealed genes that encode a candidate anti-sigma factor and an aminotransferase. Finally, we discovered several candidate virulence and host-association mechanisms, one of which appears to be a complete type III secretion system.</p> <p>Conclusions</p> <p>The improved high-quality draft genome sequence of WH6 contributes towards resolving the <it>P. fluorescens </it>species, providing additional impetus for establishing two separate lineages in <it>P. fluorescens</it>. Despite the high levels of orthology and synteny to SBW25, WH6 still had a substantial number of unique genes and represents another source for the discovery of genes with implications in affecting plant growth and health. Two genes are demonstrably necessary for GAF and further characterization of their proteins is important for developing natural products as control measure against grassy weeds. Finally, WH6 is the first isolate of <it>P. fluorescens </it>reported to encode a complete T3SS. This gives us the opportunity to explore the role of what has traditionally been thought of as a virulence mechanism for non-pathogenic interactions with plants.</p
Hybrid Hybridoma Cell Lines Which Express Anti-Zeatin Riboside, Anti-Abscisic Acid, and Hybrid Antibodies
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HalgrenAnneBotanyPlantPathologyLifeCycleExpression.pdf
Ethylene regulates multiple developmental processes during a plant life cycle, but the effect of ethylene on the upregulation of senescence-, stress-, and post-harvest-related genes in forage grasses is poorly understood. In this work, we used quantitative PCR to determine whether ethylene application affected the expression of selected cell-wall degradation related genes that are typically upregulated post-harvest. The expression levels of beta-D-glucan exohydrolase isoenzyme, alpha glucosidase, and arabinoxylan arabinofuranohydrolase isoenzyme, all putative cell wall degrading enzymes, were quantified at six points in the life cycle of the model grass species Darnel ryegrass (Lolium temulentum L.). We also quantified the expression of ACC oxidase and ACC synthase in response to ethylene application to determine if endogenous upregulation of ethylene biosynthesis occurred. Grass developmental stage had a significant impact on gene expression response to ethylene-treatment, indicating that discrete life cycle stages present different ethylene-responsive windows for treatment. Under our experimental conditions, ACC oxidase and ACC synthase expression were downregulated in response to ethylene-treatment, suggesting that exogenous ethylene served an auto-inhibitory role. Transcripts corresponding to the three cell wall degradation related genes increased significantly in response to ethylene treatment, suggesting that ethylene may have future utility in the pretreatment of lignocellulosic biomass. To our knowledge, this is the first report of a life cycle analysis of ethylene-induced genes in forage grasses
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HalgrenAnneSupplemental1.xls
Ethylene regulates multiple developmental processes during a plant life cycle, but the effect of ethylene on the upregulation of senescence-, stress-, and post-harvest-related genes in forage grasses is poorly understood. In this work, we used quantitative PCR to determine whether ethylene application affected the expression of selected cell-wall degradation related genes that are typically upregulated post-harvest. The expression levels of beta-D-glucan exohydrolase isoenzyme, alpha glucosidase, and arabinoxylan arabinofuranohydrolase isoenzyme, all putative cell wall degrading enzymes, were quantified at six points in the life cycle of the model grass species Darnel ryegrass (Lolium temulentum L.). We also quantified the expression of ACC oxidase and ACC synthase in response to ethylene application to determine if endogenous upregulation of ethylene biosynthesis occurred. Grass developmental stage had a significant impact on gene expression response to ethylene-treatment, indicating that discrete life cycle stages present different ethylene-responsive windows for treatment. Under our experimental conditions, ACC oxidase and ACC synthase expression were downregulated in response to ethylene-treatment, suggesting that exogenous ethylene served an auto-inhibitory role. Transcripts corresponding to the three cell wall degradation related genes increased significantly in response to ethylene treatment, suggesting that ethylene may have future utility in the pretreatment of lignocellulosic biomass. To our knowledge, this is the first report of a life cycle analysis of ethylene-induced genes in forage grasses
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HalgrenAnneSupplemental3.xls
Ethylene regulates multiple developmental processes during a plant life cycle, but the effect of ethylene on the upregulation of senescence-, stress-, and post-harvest-related genes in forage grasses is poorly understood. In this work, we used quantitative PCR to determine whether ethylene application affected the expression of selected cell-wall degradation related genes that are typically upregulated post-harvest. The expression levels of beta-D-glucan exohydrolase isoenzyme, alpha glucosidase, and arabinoxylan arabinofuranohydrolase isoenzyme, all putative cell wall degrading enzymes, were quantified at six points in the life cycle of the model grass species Darnel ryegrass (Lolium temulentum L.). We also quantified the expression of ACC oxidase and ACC synthase in response to ethylene application to determine if endogenous upregulation of ethylene biosynthesis occurred. Grass developmental stage had a significant impact on gene expression response to ethylene-treatment, indicating that discrete life cycle stages present different ethylene-responsive windows for treatment. Under our experimental conditions, ACC oxidase and ACC synthase expression were downregulated in response to ethylene-treatment, suggesting that exogenous ethylene served an auto-inhibitory role. Transcripts corresponding to the three cell wall degradation related genes increased significantly in response to ethylene treatment, suggesting that ethylene may have future utility in the pretreatment of lignocellulosic biomass. To our knowledge, this is the first report of a life cycle analysis of ethylene-induced genes in forage grasses
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HalgrenAnneSupplemental2.xls
Ethylene regulates multiple developmental processes during a plant life cycle, but the effect of ethylene on the upregulation of senescence-, stress-, and post-harvest-related genes in forage grasses is poorly understood. In this work, we used quantitative PCR to determine whether ethylene application affected the expression of selected cell-wall degradation related genes that are typically upregulated post-harvest. The expression levels of beta-D-glucan exohydrolase isoenzyme, alpha glucosidase, and arabinoxylan arabinofuranohydrolase isoenzyme, all putative cell wall degrading enzymes, were quantified at six points in the life cycle of the model grass species Darnel ryegrass (Lolium temulentum L.). We also quantified the expression of ACC oxidase and ACC synthase in response to ethylene application to determine if endogenous upregulation of ethylene biosynthesis occurred. Grass developmental stage had a significant impact on gene expression response to ethylene-treatment, indicating that discrete life cycle stages present different ethylene-responsive windows for treatment. Under our experimental conditions, ACC oxidase and ACC synthase expression were downregulated in response to ethylene-treatment, suggesting that exogenous ethylene served an auto-inhibitory role. Transcripts corresponding to the three cell wall degradation related genes increased significantly in response to ethylene treatment, suggesting that ethylene may have future utility in the pretreatment of lignocellulosic biomass. To our knowledge, this is the first report of a life cycle analysis of ethylene-induced genes in forage grasses