Project description:we analyzed hybrid poplar wood microcores collected thirteen months post-inoculation at the site of the active necrosis borders and identified proteins involved in molecular mechanisms responsible for preventing the Phytophthora invasion. This analysis provided novel insights into the plant-pathogen interaction and putative targets for improving tree resistance against Phytophthora
Project description:The use of hybrid-poplar tree plantations as a source for biofuels and biomass production in temperate regions of the Northern Hemisphere has also, unintentionally, increased forest isoprene emissions to the atmosphere. The consequences of increased isoprene emissions include higher rates of tropospheric ozone production and increases in atmospheric aerosol production. Using RNA interference (RNAi) to suppress isoprene emission in several gene insertion events of hybrid-poplars, we show that this trait, which has been assumed as a requisite for the tolerance of abiotic stress, is not required for high rates of woody biomass production, even in extremely hot and dry climates. Biomass production over four years in experimental poplar plantations in Arizona and Oregon was similar among genetic lines that emitted or did not emit significant amounts of isoprene. Lines that had substantially reduced isoprene emission rates also showed decreases in flavonol pigments, which reduce oxidative damage during extremes of abiotic stress; a pattern that would be expected to amplify metabolic dysfunction during abiotic stress. Compensatory increases in the expression of other proteomic components, however, such as those that disable superoxide and other free radicals, and the fact that most biomass is produced during the spring, prior to the hottest and driest part of the growing season, explains the apparent paradox of high biomass production with low isoprene emission. The results of this study provide optimism for designing agroforest plantations of the future that provide high rates of lignocellulose production while eliminating detrimental effects of isoprene emission on atmospheric quality.
Project description:Diseases of poplar caused by the fungal pathogen Sphaerulina musiva and related species are of growing concern, particular with the increasing interest in intensive popluliculture to meet increasing energy demands. S. musiva is able to cause infection on leaves, resulting in defoliation and canker formation on stems. To gain a greater understanding of the different responses of poplar species to infection with their natural Sphaerulina species, RNA-seq was conducted on leaves of Populus deltoides, P. balsamifera and P. tremuloides infected with S. musiva, S. populicola and a new undescribed species Ston1, respectively. Progression of disease symptoms, pathogen growth and host response were detected. Through the time course of infection, different and species-specific metabolic pathways were activated. In all three species, genes associated with growth and development were down-regulated, while genes involved the phenylpropanoid, terpenoid and flavonoid biosynthesis were up-regulated. Poplar defensive genes were expressed early in P. balsamifera and P. tremuloides, but delayed in P. deltoides, which correlated with the rate of disease symptoms development. This data gives an insight into the large differences in timing and expression of genes between poplar species being attacked with their native associated Sphaerulina pathogen. RNA-seq was conducted on leaves of Populus deltoides, P. balsamifera and P. tremuloides infected with S. musiva, S. populicola and a new undescribed species Ston1, respectively.
Project description:We investigated the transcriptional response of hybrid poplar (Populus trichocarpa x deltoides) source and sink leaves to simulated herbivory (mechanical wounding plus the application of Malacosoma disstria oral secretions) over a 24 hour time course. Experiments were conducted using clonal trees under greenhouse conditions at the University of British Columbia. We used the 15.5K poplar cDNA microarray platform previously described by Ralph et al. (Molecular Ecology 2006, 15:1275-1297). Differentially expressed genes were determined using three criteria: fold-change between treated and untreated control leaves > 1.5-fold, P value < 0.05 and Q value < 0.05. This study identified > 3,000 differentially expressed genes in response to simulated insect feeding damage, which possess distinct source/sink and treated/systemic patterns.
Project description:We investigated the transcriptional response of hybrid poplar (Populus trichocarpa x deltoides) source and sink leaves to simulated herbivory (mechanical wounding plus the application of Malacosoma disstria oral secretions) over a 24 hour time course. Experiments were conducted using clonal trees under greenhouse conditions at the University of British Columbia. We used the 15.5K poplar cDNA microarray platform previously described by Ralph et al. (Molecular Ecology 2006, 15:1275-1297). Differentially expressed genes were determined using three criteria: fold-change between treated and untreated control leaves > 1.5-fold, P value < 0.05 and Q value < 0.05. This study identified > 3,000 differentially expressed genes in response to simulated insect feeding damage, which possess distinct source/sink and treated/systemic patterns.
Project description:Plasma membrane intrinsic proteins (PIPs) are one subfamily of aquaporins that mediate the transmembrane transport of water. To reveal their function in poplar, we generated transgenic poplar plants in which the translation of PIP genes was downregulated by RNA interference investigated these plants with a comprehensive leaf plasma membrane proteome and physiome analysis. First, inhibition of PIP synthesis strongly altered the leaf plasma membrane protein composition. Strikingly, several signaling components and transporters involved in the regulation of stomatal movement were differentially regulated in transgenic poplars. Furthermore, hormonal crosstalk related to abscisic acid, auxin and brassinosteroids was altered, in addition to cell wall biosynthesis/cutinization, the organization of cellular structures and membrane trafficking. A physiological analysis confirmed the proteomic results. The leaves had wider opened stomata and higher net CO2 assimilation and transpiration rates as well as greater mesophyll conductance for CO2 (gm) and leaf hydraulic conductance (Kleaf). Based on these results, we conclude that PIP proteins not only play essential roles in whole leaf water and CO2 flux but have important roles in the regulation of stomatal movement.
Project description:Global gene expression pattern of different poplar tissue types were determined using a Nimblegen microarray based on JGI v1.1 gene models. All tissue except reproductive tissue were obtained from the same clone used for the poplar genome sequencing project (Populus trichocarpa Nisqually-1). Reproductive tissue were from wild Populus trichocarpa trees.
Project description:Illumina HiSeq technology was used to generate mRNA profiles from Populus tremula x alba INRA 717-1B4 roots treated with Methyl jasmonate. Samples were harvested after two weeks either from untreated control roots or from Methyl jasmonate treated roots. Paired-end (2X100bp) reads were generated and aligned to the Populus trichocarpa (http://www.phytozome.net/poplar.php) using CLC Genomics Workbench 6. mRNA profiles from Populus tremula x alba INRA 717-1B4 roots treated with Methyl jasmonate as well as from control roots were generated by paired-end (2X100bp) Illumina HiSeq sequencing. Four samples were sequenced per lane, two biological replicates per treatment.
Project description:The Poplar transcriptome was analyzed in Populus tremulaxPopulus alba clone 717-1B4 control roots and in two poplar lines overexpressing MiSSP7.