Project description:TA inhibits cellulose synthesis but its actual mode of action is unknown. Addition of TA to hybrid poplar (Populus trichocarpa x Populus deltoides) cell suspensions can activate a cellular program leading to cell death. In contrast, it is possible to habituate hybrid poplar cell cultures to grow in the presence of TA levels that would normally induce cell death. This habituation was performed by adding increasing levels of TA to cell cultures at the time of subculture over a period of 12 months. TA-habituated cells were then cultured in the absence of TA for more than 18 months. These cells displayed a reduced size and growth compared to control cells and had fragmented vacuoles filled with electron-dense material. Habituation to TA was associated with changes in the cell wall composition, with a reduction in cellulose and an increase in pectin levels. Remarkably, high level of resistance to TA was maintained in TA-habituated cells even after being cultured in the absence of TA. Moreover, these cells exhibited enhanced resistance to two other inhibitors of cellulose biosynthesis, dichlobenil and isoxaben. Analysis of gene expression in TA-habituated cells using Affymetrix GeneChip Poplar Genome Array revealed that durable resistance to TA is associated with a major and complex reprogramming of gene expression implicating processes such as cell wall synthesis and modification, lignin and flavonoid synthesis, as well as DNA and chromatin modifications. Experiment Overall Design: Each sample was taken from an individual flask of control cells or TA-habituated resistant cells grown without the toxin for 18 months (TA(-)hab cells) that had grown for 5 d after subculture. Six arrays were hybridized, representing 3 arrays per cell type.
Project description:The purpose of this study was to evaluate a set of 6-7 long oligonucleotide probes developed based on the sequence of the Populus trichocarpa genome, that are optimal for gene expression analysis of P. deltoides and a hybrid of P. deltoides and P. trichocarpa. To evaluate these probes, multiple tissues (differentiating xyle, leaf and whole-root) of a pure P. deltoides and a hybrid (P. deltoides X P. trichocarpa) were transcript profiled for identification of one or more probes that are not biased towards one or the other genotype.
Project description:Populus deltoides and Populus trichocarpa were exposed to either ambient air or an acute ozone exposure of 200 ppb for 9 hrs and ozone response was profiled for each genotype by hybridising control against ozone-exposed samples per genotype. Keywords: stress response, genotype comparrison, ozone exposure
Project description:Populus deltoides and Populus trichocarpa were exposed to either ambient air or an acute ozone exposure of 200 ppb for 9 hrs and ozone response was profiled for each genotype by hybridising control against ozone-exposed samples per genotype. Keywords: stress response, genotype comparrison, ozone exposure RNA was extracted from the fifth leaf below the first fully unfurled leaf for each plant. Control and ozone-exposed plants were then randomly paired for hybridisation.
Project description:The expression of stress-related genes induced by feeding of chestnut moth larvae (Conistra vaccinii L.) was studied with Vitreoscilla hemoglobin-expressing (VHb) and non-transgenic hybrid aspen lines (Populus tremula x P. tremuloides). Besides the herbivore-injured leaves (L1), cDNA microarray analyses were conducted using uninjured leaves of hybrid aspen lines positioned above (A) and below (B) the herbivory exposed leaves.
Project description:The expression of stress-related genes induced by feeding of chestnut moth larvae (Conistra vaccinii L.) was studied with Vitreoscilla hemoglobin-expressing (VHb) and non-transgenic hybrid aspen lines (Populus tremula x P. tremuloides). Besides the herbivore-injured leaves (L1), cDNA microarray analyses were conducted using uninjured leaves of hybrid aspen lines positioned above (A) and below (B) the herbivory exposed leaves. Two-condition experiment, control vs. herbivory exposure. Two hybrid aspen lines: non-transgenic V617 and VHb expressing V617 /45. Of each plant, three leaf types were analysed: the injured/uninjured leaf (L1) and nonorthostichous leaf positioned above (A) and below (B). Biological replicates: 3. On each array, two samples representing L1, A or B leaf type of control and herbivory treatment of either V617 or V617/45 line. line V617: wt_A_rep1-3, wt_B_rep1-3, wt_L1_rep1-3 line V617/45: VHb_A_rep1-3, VHb_B_rep1-3, VHb_L1_rep1-3 leaf type A: wt_A_rep1-3, VHb_A_rep1-3 leaf type B: wt_B_rep1-3, VHb_B_rep1-4 leaf type L1: wt_L1_rep1-3, VHb_L1_rep1-5
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.