BACKGROUND:Nitrogen is an important nutrient, often limiting plant productivity and yield. In poplars, woody crops used as feedstock for renewable resources and bioenergy, nitrogen fertilization accelerates growth of the young, expanding stem internodes. The underlying molecular mechanisms of nitrogen use for extension growth in poplars are not well understood. The aim of this study was to dissect the nitrogen-responsive transcriptional network in the elongation zone of Populus trichocarpa in re ...[more]
Project description:The majority of trees live in association with symbiotic fungi, which facilitate their access to soil nutrients. The ectomycorrhizal symbiosis represents a complex biological system involving multifaceted interactions between the two partners. The establishment of the symbiosis depends on various conditions (e.g. climate), but also on the genetic traits of the partners. To evaluate the impact of the genetic predisposition on the development and functioning of ectomycorrhizas, we compared the transcriptome of roots from Populus trichocarpa and Populus deltoides colonized with Laccaria bicolor. The Populus whole-genome expression array version 2.0 (S. DiFazio, A. Brunner, P. Dharmawardhana, and K. Munn, unpublished data) manufactured by NimbleGen Systems Limited (Madison, WI) contains in duplicates three independent, non-identical, 60-mer probes per whole gene model plus control probes and labeling controls. Included in the microarray are 65,965 probe sets corresponding to 55,970 gene models predicted on the P.trichocarpa genome sequence version 1.0 and 9,995 aspen cDNA sequences (Populus tremula, Populus tremuloides, and P. tremula x P. tremuloides). NimbleGen whole genome microarray analyses were performed in triplicate as per manufacturer's instructions. We carried out six hybridizations (NimbleGen) with samples derived from Populus trichocarpa and Populus deltoides mycorrhizal root tips. Three samples (biological replicates) originated from Populus trichocarpa (GSM648401, GSM648403, GSM648405) and three biological replicates from Populus deltoides (GSM648408, GSM648411, GSM648414). cDNA was synthesized using CLONTECH Super Smart cDNA Synthesis kit containing an amplification step on the cDNA level. All samples were labeled with Cy3.
Project description:The atmosphere CO2 concentration keeps increasing every year. Use the Affymetrix poplar gene chip to confirm the expression changes in key genes in the triploid white poplar due to the influence of elevated CO2 concentrations. We used microarrays to detail the global programme of gene expression under normal and elevated CO2 concentrations. Gene expression of triploid white poplar ((P. tomentosa × P. bolleana）× P. tomentosa) leaves were investigated by using the Affymetrix poplar genome gene chip, after grown in controlled environment chambers under three different CO2 concentrations. Poplar leaves were subjected to normal CO2 concentrations (T0) and elevated CO2 concentrations (T1, 550 ppm and T2, 720 ppm) treatments three months.
Project description:Stem cuttings of P. trichocarpa (clone 101-74) were rooted in liquid medium without growth regulators (basal medium). The first emerging roots were observed on cuttings 6 days after the start of culture. The highest average root number per cutting (10 ± 2 roots/cutting) was obtained after 14 days. The first macroscopic evidence of root initiation was the appearance of root primordia, as lateral bulges observed at the stem surface 3 to 4 days after transfer to basal medium. Stem cross-sections showed intensely dividing cells forming root primordial. One to two days later the bark split and the organized sequence of cell division and differentiation steps in the primordium led to the establishment of the main root tissues, as well as the vascular connections of the incipient root with the pre-existing stem vasculature. Subsequently, the outgrowth and emergence of the adventitious root occurred. We refer to the dormant cutting as stage 0, the organizing primordium as stage 1, the primordium differentiation as stage 2. To examine changes in gene transcription associated with the development of adventitious roots, we monitored the transcript levels in differentiating primordia using microarrays. cDNA was prepared from replicate sets of P. trichocarpa rooted cuttings harvested at stages 0, 1 and 2. The Populus whole-genome expression array version 2.0 manufactured by NimbleGen Systems Limited (Madison, WI) contains in duplicates three independent, non-identical, 60-mer probes per whole gene model plus control probes and labeling controls. Included in the microarray are 65,965 probe sets corresponding to 55,970 gene models predicted on the P. trichocarpa genome sequence version 1.0 and 9,995 aspen cDNA sequences (Populus tremula, Populus tremuloides, and P. tremula x P. tremuloides). NimbleGen whole genome microarray analyses were performed in triplicate as per manufacturers instructions. We carried out nine hybridizations (NimbleGen) with samples derived from three early developmental stages of P. trichocarpa adventitious roots. cDNA was synthesized using CLONTECH Smart cDNA Synthesis kit containing an amplification step on the cDNA level. All samples were labeled with Cy3.
Project description:The heat shock response continues to be layered with additional complexity as interactions and cross-talk among heat shock proteins, the reactive oxygen network and hormonal signaling are discovered. However, comparative analyses exploring variation in each of these processes among species remains relatively unexplored. In controlled environment experiments, photosynthetic response curves were conducted from 22 °C to 42 °C and indicated that temperature optimum of light saturated photosynthesis was greater for Glycine max relative to Arabidopsis thaliana or Populus trichocarpa. Transcript profiles were taken at defined states along the temperature response curves and inferred pathway analysis revealed species-specific variation in the abiotic stress and the minor carbohydrate raffinose/galactinol pathways. A weighted gene co-expression network approach was used to group individual genes into network modules linking biochemical measures of the antioxidant system to leaf-level photosynthesis among P. trichocarpa, G. max and A. thaliana. Network enabled results revealed an expansion in the G. max HSP17 protein family and divergence in the regulation of the antioxidant and heat shock module relative to P. trichocarpa and A. thaliana. These results indicate that although the heat shock response is highly conserved, there is considerable species-specific variation in its regulation. fully expanded leaf samples from 4 randomly collected plants per species were harvested at 4 physiological states as determined from prior gas exchange measurements (growth temperature - baseline, photosynthetic optimum, 20% inhibition of optimum and 30% inhibition of optimum).This resulted in 16 separate samples hybridized to independent microarrays totaling 4 – replicates x 4 physiological states).
Project description:Changes in gene expression in P. trichocarpa leaves was measured in response to growth competition by P. x canescens.Square petri dishes (12 x 12 cm) were filled autoclaved sand, 3 plantlets and Woody Plant Medium (WPM). In each petri dish we are growing 3 plantlets. As control 3 plantlets of P. trichocarpa and for the experiment a mixture of P. canescens and P. trichocarpa were P. trichocarpa is all the time the middle plantlet.
Project description:Populus x canescens was inoculated with Paxillus involutus and grown in a climate chamber for 13 weeks. Afterwards, plants were salt stressed for 18 additional days with 150 mM NaCl in the nutrient solution. This resulted in 4 different treatments: no mycorrhiza<br>control (NC), mycorrhiza/control (MC), no mycorrhiza/salt (NS), mycorrhiza/salt (MS).