Acceleration of disulfide-coupled protein folding using glutathione derivatives

Protein folding occurs simultaneously with disulfide bond formation. In general, the in vitro folding of proteins containing disulfide bond(s) is carried out in the presence of redox reagents, such as glutathione, to permit native disulfide pairing to occur. It is well known that the formation of a disulfide bond and the correct tertiary structure of a target protein are strongly affected by the redox reagent used. However, little is known concerning the role of each amino acid residue of the redox reagent, such as glutathione. Therefore, we prepared glutathione derivatives - glutamyl-cysteinyl-arginine (ECR) and arginyl-cysteinyl-glycine (RCG) - and examined their ability to facilitate protein folding using lysozyme and prouroguanylin as model proteins. When the reduced and oxidized forms of RCG were used, folding recovery was greater than that for a typical glutathione redox system. This was particularly true when high protein concentrations were employed, whereas folding recovery using ECR was similar to that of the glutathione redox system. Kinetic analyses of the oxidative folding of prouroguanylin revealed that the folding velocity (K(RCG) = 3.69 × 10(-3) s(-1)) using reduced RCG/oxidized RCG was approximately threefold higher than that using reduced glutathione/oxidized glutathione. In addition, folding experiments using only the oxidized form of RCG or glutathione indicated that prouroguanylin was converted to the native conformation more efficiently in the case of RCG, compared with glutathione. The findings indicate that a positively charged redox molecule is preferred to accelerate disulfide-exchange reactions and that the RCG system is effective in mediating the formation of native disulfide bonds in proteins.     

Riparian populations of minnesota reed canarygrass (Phalaris arundinacea) are most likely native,based on SNPs (DArTseqLD)

The native vs. exotic status of reed canarygrass (RCG), a major invasive species of Minnesota wetlands, is unknown. The aim of this study was to investigate this native vs. exotic status to enhance its management. Genetic comparison of wild RCG populations from six Minnesota and six Czech Republic rivers was performed. A total of 2521 polymorphic SNP markers (single nucleotide polymorphisms) were used to evaluate 478 RCG samples across all collections. In the PCoA, all (n = 256) tested extant wild, riparian RCG genotypes from six Minnesota Rivers and six Czech Republic Rivers were genetically distinct, although some SNPs were common in both populations since they are the same species. DAPC analysis also resulted in the formation of two primary clusters separating the Minnesota Rivers and Czech Republic Rivers riparian samples, with little overlap; STRUCTURE analysis also supported this clustering with k = 4 groups as it separated the Czech Republic Rivers populations into three groups, along with Minnesota Rivers. The uniformity of PCoA, DAPC, STRUCTURE, and Evanno results indicates the distinct separation of Minnesota Rivers and Czech Republic Rivers populations. Portions of the genome (specific SNPs) are preserved or in common across continents, as indicated by STRUCTURE similarities. Nonetheless, overall significant SNP differences between the continents indicate that the Minnesota riparian populations are distinct enough from the European (Czech) collections to be delineated as native N. American RCG. PCoA of all the Minnesota RCG collections clustered Minnesota Rivers, Herbarium, Extant Herbarium, Research Field and Native Field collections together. STRUCTURE analysis (k = 2; Evanno) divided these Minnesota collections from the Commercial Field and Cultivars collections. There are two genetically distinct groups of RCG in Minnesota and since the Minnesota Rivers, the Research Field, the Native Field and pre-1930 herbaria collections clustered together, they are most likely native N. American types. Analysis of molecular variance (AMOVA) indicated that the genetic variation was more significant within, rather than among, the RCG populations. Native, historic herbaria types cluster together with all wild RCG river populations in Minnesota, all of which were distinct from those in Central Europe, suggesting native RCG type persistence in N. America. Also, cultivated forage types of RCG are distinct from wild RCG Minnesota river populations. The SNP genetic data shows that riparian Minnesota RCG populations are native. These data will facilitate future management strategies to control RCG as a native, but invasive, species.

     

SESAME: Scalable, Environment Sensitive Access Management Engine

As computing technology becomes more pervasive and mobile services are deployed, applications will need flexible access control mechanisms. Although lots of researches have been done on access control, these efforts focus on relatively static scenarios where access depends on identity of the subject. They do not address access control issues for pervasive applications where the access privileges of a subject not only depend on its identity but also on its current context and state. In this paper, we present the SESAME dynamic context-aware access control mechanism for pervasive applications. SESAME complements current authorization mechanisms to dynamically grant and adapt permissions to users based on their current context. The underlying dynamic role based access control (DRBAC) model extends the classic role based access control (RBAC). We also present a prototype implementation of SESAME and DRBAC with the Discover computational collaboratory and an experimental evaluation of its overheads. Guangsen Zhang is Ph.D. student in the Department of Electrical and Computer Engineering at Rutgers University. He received his MS from Rutgers University. His research interests include parallel & distributed computing, distributed system security. Manish Parashar is an Associate Professor in the Department of Electrical and Computer Engineering at Rutgers University. His research interests include autonomic computing, parallel & distributed computing, scientific computing, and software engineering.     

Effects of low-spatial frequency components of fearful faces on fusiform cortex activity

Emotive faces elicit neural responses even when they are not consciously perceived. We used faces hybridized from spatial frequency-filtered individual stimuli to study processing of facial emotion. Employing event-related functional magnetic resonance imaging (fMRI), we show enhanced fusiform cortex responses to hybrid faces containing fearful expressions when such emotional cues are present in the low-spatial frequency (LSF) range. Critically, this effect is independent of whether subjects use LSF or high-spatial frequency (HSF) information to make gender judgments on the hybridized faces. The magnitude of this fusiform enhancement predicts behavioral slowing in response times when participants report HSF information of the hybrid stimulus in the presence of fear in the unreported LSF components. Thus, emotional modulation of a face-responsive region of fusiform is driven by the low-frequency components of the stimulus, an effect independent of subjects' reported perception but evident in an incidental measure of behavioral performance.     

Priority Based Messaging for Software Distributed Shared Memory

Software Distributed Shared Memory (DSM) systems can be used to provide a coherent shared address space on multicomputers and other parallel systems without support for shared memory in hardware. The coherency software automatically translates shared memory accesses to explicit messages exchanged among the nodes in the system. Many applications exhibit a good performance on such systems but it has been shown that, for some applications, performance critical messages can be delayed behind less important messages because of the enqueuing behavior in the communication libraries used in current systems. We present in this paper a new portable communication library that supports priorities to remedy this situation. We describe an implementation of the communication library and a quantitative model that is used to estimate the performance impact of priorities for a typical situation. Using the model, we show that the use of high-priority communication reduces the latency of performance critical messages substantially over a wide range of network design parameters. The latency is reduced with up to 10–25% for each delaying low priority message in the queue ahead.     

Establishment of reed canary grass with perennial legumes or barley and different fertilization treatments: effects on yield,botanical composition and nitrogen fixation

In two field experiments in northern Sweden, we investigated if intercropping reed canary grass (RCG; Phalaris arundinacea L.) with nitrogen‐fixing perennial legumes could reduce N‐fertilizer requirements and also if RCG ash or sewage sludge could be used as a supplement for mineral P and K. We compared biomass production, N uptake and N‐fixation of RCG in monoculture and mixtures of RCG with alsike clover (Trifolium hybridum L.), red clover (Trifolium pratense L.), goat's rue (Galega orientalis Lam.) and kura clover (Trifolium ambiguum M. Bieb.). In one experiment, RCG was also undersown in barley (Hordeum vulgare L.). Three fertilization treatments were applied: 100 kg N ha^?1, 50 kg N ha^?1 and 50 kg N ha^?1 + RCG ash/sewage sludge. We used a delayed harvest method: cutting the biomass in late autumn, leaving it on the field during the winter and harvesting in spring. The legume biomass of the mixtures at the inland experimental site was small and did not affect RCG growth negatively. At the coastal site, competition from higher amount of clover biomass affected RCG growth and spring yield negatively. N‐fixation in red clover and alsike clover mixtures in the first production year approximately covered half of recommended N‐fertilization rate. Goat's rue and kura clover did not establish well at the costal site, but at the inland site goat's rue formed a small but vital undergrowth. RCG undersown in barley gave lower yield, both in autumn and spring, than the other treatments. The high N treatment gave a higher spring yield at the inland site than the low N treatments, but there were no differences due to fertilization treatments at the coastal site. For spring harvest, there were no yield benefits of RCG/legume intercropping compared with RCG monoculture. However, intercropping might be more beneficial in a two‐harvest system.     

A Framework for Adaptive Cluster Computing Using JavaSpaces

Heterogeneous networked clusters are being increasingly used as platforms for resource-intensive parallel and distributed applications. The fundamental underlying idea is to provide large amounts of processing capacity over extended periods of time by harnessing the idle and available resources on the network in an opportunistic manner. In this paper we present the design, implementation and evaluation of a framework that uses JavaSpaces to support this type of opportunistic adaptive parallel/distributed computing over networked clusters in a non-intrusive manner. The framework targets applications exhibiting coarse grained parallelism and has three key features: (1) portability across heterogeneous platforms, (2) minimal configuration overheads for participating nodes, and (3) automated system state monitoring (using SNMP) to ensure non-intrusive behavior. Experimental results presented in this paper demonstrate that for applications that can be broken into coarse-grained, relatively independent tasks, the opportunistic adaptive parallel computing framework can provide performance gains. Furthermore, the results indicate that monitoring and reacting to the current system state minimizes the intrusiveness of the framework.     

Ash as a phosphorus fertilizer to reed canary grass: effects of nutrient and heavy metal composition on plant and soil

Fertilization effects and risks of heavy metal enrichment were studied in a field experiment, in which plots of reed canary grass (RCG) were treated annually with three different fertilizers: Ash from co‐combustion of RCG and municipal wastes (mixed ash), pure RCG ash, and commercial fertilizer (control). RCG ash is a waste product that is currently expensive to dispose of. The amounts of nutrients applied annually were 100 kg ha^?1 N, 15 kg ha^?1 P, and 80 kg ha^?1 K in all treatments. In the ash treatments, all P derived from ash, whereas N and part of the K were supplemented by fertilizers. The amount of heavy metals exceeded the limits set by the Swedish Environmental Protection Agency for all elements analyzed in the mixed ash and for Ni and Cr in the RCG ash. There were no significant differences between treatments in terms of RCG dry matter yield obtained at harvest in spring, or in heavy metal concentrations in the biomass. Soil samples from 0–5 cm, 5–10 cm, and 10–20 cm below the surface showed significant differences between treatments for the concentration of Cd, Cr, Cu, Pb, and Zn, with higher concentrations in plots fertilized with mixed ash than in the control. Neither spring yield nor soil available P was reduced by using ash instead of mineral P fertilizer, suggesting that pure RCG ash can be used to complement commercial fertilizer, albeit less frequently than here. However, ash derived from co‐combusting RCG with different waste materials (mixed ash treatment) should not be used in RCG production due to the high heavy metal content.     

Development of high penicillin producing strains for solid state fermentation

Penicillin production with an industrial strain and 4 strains of P. chrysogenum, in solid state fermentation (SSF) and liquid submerged fermentation (LSF), was determined. Their ability to produce the antibiotic in SSF in relation to their capacity to do so in LSF was evaluated. this was done by calculating the ratio PS/PL (production in SSF/production in LSF), which was called relative production. Clones were isolated from each strain and evaluated in a similar way. The strains presented different relative productions (from 1.4 to 2.5). Within the clones, a much wider range of relative productions was observed (0.6 to 16.7). On the other hand, the highest-producing strains in LSF were also the highest producers in SSF. This indicates that the production potential of a strain is an important factor in its production level in SSF. Moreover, the highest penicillin producing ciones (9,500 to 10,500 microg of penicillin/g were generated from high-yielding strains (P2 and ASP-78). However, the higher-producing strains (in LSF) showed lower relative performance, suggesting that higher producing strains tend to express less efficiently their potential in SSF. In this study, several overproducing clones, particularly suited for SSF, were obtained by the procedures followed. Production increases of 500 to 600 %, in this culture system, were achieved.     

Biological consequences of invasion by reed canary grass (<Emphasis Type="Italic">Phalaris arundinacea</Emphasis>)

Although they are typically assumed to be negative, the consequences of plant invasions for native diversity or biological integrity are seldom broadly quantified (i.e., for multiple taxa or across large regions). We investigated the impacts associated with invasion of wetlands by reed canary grass (Phalaris arundinacea L.; RCG) on plants and several animal groups. In a local study, we compared plants, arthropods, and small mammals on treatment plots with reduced RCG dominance to those on highly invaded plots. We also conducted a companion study, where we measured RCG dominance and plants, arthropods, and birds in 82 randomly selected wetlands across Illinois (USA) to determine if our experimental results were consistent in communities across the region. Plant diversity, floristic quality, and diversity and abundance of Homopteran insects decreased with RCG dominance in all instances. Richness and abundance of all other arthropods decreased with increasing RCG in the local study, but no trend was detected in communities statewide. No relationship between total abundance or richness of small mammals (local) or birds (statewide) with RCG was detected. However, voles and shrews were more abundant, and mice less abundant, in RCG-dominated plots. These results support the hypothesis that there are negative effects for multiple taxa from RCG invasion. Because negative effects observed in the local study either corroborated, or were neutral with respect to results from statewide surveys, they suggest that native biodiversity and biological integrity are being dampened across wide areas of this invader’s range.     

Climate-based identification of suitable cropping areas for giant reed and reed canary grass on marginal land in Central and Southern Europe under climate change

Giant reed (GR) and reed canary grass (RCG) have emerged as promising perennial industrial crops for providing sustainable bioenergy from marginal land. However, there is great uncertainty among farmers and researchers about where these crops can be grown in the future due to climate change, which complicates a timely transition to a bioeconomy. Therefore, this study quantifies marginal land and suitable cropping areas for GR and RCG in Europe, as well as their overlap. To derive these areas, the present (1991–2020) and future (2071–2100, RCP8.5) growing degree days, growing season length, annual precipitation, and aridity index were analyzed using the E-OBS observational dataset and EURO-CORDEX regional climate simulations. The study concludes that while marginal land will decrease by ~18%, GR and RCG will profit from the changing European climate, increasing by ~24% and ~13%, respectively. Looking at regions of overlap between marginal land and the selected crops, a decrease of ~87% and an increase of ~462% is projected for RCG and GR, respectively. This is due to marginal land shifting southward, benefitting the warm-season grass GR, while RCG prefers cooler climates.     

Atmospheric impact of bioenergy based on perennial crop (reed canary grass,Phalaris arundinaceae,L.) cultivation on a drained boreal organic soil

Marginal organic soils, abundant in the boreal region, are being increasingly used for bioenergy crop cultivation. Using long‐term field experimental data on greenhouse gas (GHG) balance from a perennial bioenergy crop [reed canary grass (RCG), Phalaris arundinaceae L.] cultivated on a drained organic soil as an example, we show here for the first time that, with a proper cultivation and land‐use practice, environmentally sound bioenergy production is possible on these problematic soil types. We performed a life cycle assessment (LCA) for RCG on this organic soil. We found that, on an average, this system produces 40% less CO₂‐equivalents per MWh of energy in comparison with a conventional energy source such as coal. Climatic conditions regulating the RCG carbon exchange processes have a high impact on the benefits from this bioenergy production system. Under appropriate hydrological conditions, this system can even be carbon‐negative. An LCA sensitivity analysis revealed that net ecosystem CO₂ exchange and crop yield are the major LCA components, while non‐CO₂ GHG emissions and costs associated with crop production are the minor ones. Net bioenergy GHG emissions resulting from restricted net CO₂ uptake and low crop yields, due to climatic and moisture stress during dry years, were comparable with coal emissions. However, net bioenergy emissions during wet years with high net uptake and crop yield were only a third of the coal emissions. As long‐term experimental data on GHG balance of bioenergy production are scarce, scientific data stemming from field experiments are needed in shaping renewable energy source policies.     

Phytochemical complementarities among endophyte-infected tall fescue, reed canarygrass, birdsfoot trefoil and alfalfa affect cattle foraging

We determined whether plant diversity and sequence of plant ingestion affected foraging when cattle chose from plants that varied in concentrations of alkaloids, tannins and saponins. We hypothesized cattle that ate high-alkaloid grasses (endophyte-infected tall fescue (TF) or reed canarygrass (RCG)) would prefer forages high in tannins (birdsfoot trefoil, BFT+) or saponins (alfalfa, ALF+), because tannins and saponins can bind to alkaloids, presumably reducing their absorption. We further hypothesized that forages with tannins or saponins consumed before, rather than after, foraging on high-alkaloid grasses would promote greater use of those grasses presumably by binding to alkaloids, thereby reducing their absorption. In Phase 1, cattle (n = 32) grazed on either high (+) or low (-) alkaloid grass (TF or RCG) pastures for 30 min each morning at 0600 h and were then offered a choice of BFT+, BFT-, ALF+ and ALF- for 60 min each day for 12 days. In Phase 2, cattle (n = 32) were first offered a choice of BFT+ or ALF+ for 30 min at 0600 h and then placed on grass (TF+ or -, or RCG+ or -) pastures for 60 min for 12 days. In both phases, we had four spatial replications of four treatments with 2 per calves assigned to each of the 16 replications per treatment combinations. Scan samples of individuals at 2-min intervals were used to determine incidence of foraging on each plant species (%). Cattle grazed more on RCG than on TF in Phases 1 (62% v. 27%; P = 0.0015) and 2 (71% v. 32%; P = 0.0005). In Phase 1, cattle that first foraged on RCG+ or TF- subsequently preferred ALF over BFT, whereas cattle offered RCG- or TF+ foraged on ALF and BFT equally. Foraging by cattle on RCG was cyclic during Phase 1, whereas cattle foraging on TF markedly decreased incidence of use of TF from 41% to only 16% by the end of the 12-day trial (P = 0.0029). Contrary to the cyclic (RCG) or steadily declining (TF) use of grasses in Phase 1, cattle steadily and dramatically increased foraging on both RCG and TF throughout Phase 2, when they first grazed BFT+ or ALF+ followed by high-alkaloid grasses (P = 0.0159). Our findings suggest that in plant species the sequence of ingestion influenced foraging behavior of cattle and that secondary compounds influenced those responses.     

Age-Related Differences in Spatial Frequency Processing during Scene Categorization

Visual analysis of real-life scenes starts with the parallel extraction of different visual elementary features at different spatial frequencies. The global shape of the scene is mainly contained in low spatial frequencies (LSF), and the edges and borders of objects are mainly contained in high spatial frequencies (HSF). The present fMRI study investigates the effect of age on the spatial frequency processing in scenes. Young and elderly participants performed a categorization task (indoor vs. outdoor) on LSF and HSF scenes. Behavioral results revealed performance degradation for elderly participants only when categorizing HSF scenes. At the cortical level, young participants exhibited retinotopic organization of spatial frequency processing, characterized by medial activation in the anterior part of the occipital lobe for LSF scenes (compared to HSF), and the lateral activation in the posterior part of the occipital lobe for HSF scenes (compared to LSF). Elderly participants showed activation only in the anterior part of the occipital lobe for LSF scenes (compared to HSF), but not significant activation for HSF (compared to LSF). Furthermore, a ROI analysis revealed that the parahippocampal place area, a scene-selective region, was less activated for HSF than LSF for elderly participants only. Comparison between groups revealed greater activation of the right inferior occipital gyrus in young participants than in elderly participants for HSF. Activation of temporo-parietal regions was greater in elderly participants irrespective of spatial frequencies. The present findings indicate a specific low-contrasted HSF deficit for normal elderly people, in association with an occipito-temporal cortex dysfunction, and a functional reorganization of the categorization of filtered scenes.     

Antiproliferative effects of galectin-1 from <Emphasis Type="BoldItalic">Rana catesbeiana</Emphasis> eggs on human leukemia cells and its binding proteins in human cells

Galectin-1 from American bullfrog, RCG1, was isolated to high purity, and its growth inhibitory properties against human cells were examined. The results demonstrated that highly purified RCG1 induced large cell aggregates and revealed cell-type-specific growth inhibition. It significantly inhibited all human leukemia cell lines tested such as HL-60, U937, and K562 cells but did not inhibit human colon cancer cell line, Colo 201, or mouse mammary tumor cell line FM3A cells. Although most of the galectin-induced growth inhibitions are known to be apoptic, RCG1 induced growth arrest and neither apoptosis nor necrosis. RCG1-mediated growth inhibition was specifically suppressed by the corresponding sugar, lactose, but not by sucrose or even the structurally similar sugar, melibiose. Several studies have reported that galectin-mediated biological functions were modulated by charge modification. Since the high purity of RCG1 was demonstrated but a moderate degree of growth inhibition occurred, it is possible protein charge modification was examined by isoelectric focusing, and it was found to be highly heterogeneous in charge. RCG1 binding proteins in human cells were analyzed by lectin blotting using biotinylated RCG1, and lectin blotting revealed that in human cell extracts the specific proteins at molecular weight 37 and 50 kDa possessed the responsive features of RCG1 binding and lactose competition.     

A series of murine interleukin molecules which stimulate both murine and human lymphocytes: I. Production by Phytolacca americana (pokeweed) lectin 2 (Pa-2)-stimulated thymus and thymus-derived cells

Cell-free supernatant fluid, from cultures of Phytolacca americana (pokeweed) lectin 2 (Pa-2)-pulsed murine spleen or thymus cells, contains factors which induce cultured lymphocytes to differentiate into IgM-secreting cells (assayed by a reverse plaque technique) and to proliferate (measured by the incorporation of tritiated thymidine) without the addition of mitogen. The factors in this supernatant fluid responsible for these activities have been designated as lymphocyte stimulating factors (LSF). LSF showed no genetic restrictions related to the major histocompatability complex; LSF made in one strain of mice worked in other strains. Indeed, LSF is not restricted by species barriers; human peripheral blood mononuclear cells were also stimulated by murine LSF to proliferate and differentiate into immunoglobulin-secreting cells without further addition of antigen or mitogen. Maximum production of LSF was achieved within 12 hr of culture and was independent of cell division. In contrast to TRF, no further production of LSF was detectable after 24 hr of culture. Unlike T-cell growth factor, this material stimulated increased mitosis of thymic, T, and B lymphocytes without the addition of mitogen or antigen. LSF also stimulated polyclonal B-cell differentiation into IgM-secreting cells. Maximal numbers of immunoglobulin-secreting cells were generated when LSF was added at the initiation of the culture. Indeed, unlike TRF, LSF needed to be present only during the first 6 hr of culture to achieve maximum stimulation, and did not require the presence of antigen. The production of LSF by a T-cell population in the spleen was shown by two independent methods. Spleen cells treated with anti-Thy 1 plus complement failed to produce detectable levels of LSF. On the other hand, purified populations of surface immunoglobulin-negative spleen cells produced LSF. Furthermore, the subset of thymocytes responsible for LSF production was the small population (approximately 10%) of cells in the thymus, which are not agglutinated by peanut agglutinin.     

Labile Serum Factor and Its Effect on Arbovirus Neutralization

Enhancement of neutralization of Sindbis, Venezuelan equine encephalitis, Eastern equine encephalitis, Western equine encephalitis, and St. Louis encephalitis viruses by labile serum factor (LSF) in human serum and plasma was demonstrated. Human serum and plasma could be diluted 1:8 and 1:16 and still retain some LSF activity. Satisfactory storage temperatures for retention of LSF activity were −20 or −56 C. Repeated freeze-thaw cycles of serum did not alter LSF activity, but the activity was completely eliminated by heating at 56 C for 5 min. LSF of human serum equally enhanced neutralization by Sindbis immune mouse and rabbit sera; these results suggest a lack of species specificity. Rehydrated lyophilized gunea pig complement did not restore LSF activity to heated human plasma. Serum components responsible for LSF activity were not dialyzable. Discovery of fresh serum without LSF activity established the need to pretest all sera used as LSF sources.     

Enantioselective reduction of pentoxifylline to lisofylline using whole-cell Lactobacillus kefiri biotransformation

Lisofylline (LSF) is a drug candidate that has been under investigation for acute respiratory distress syndrome, acute lung injury, septic shock and mucositis. As LSF is not commercially available in our country, we produced it for pharmacokinetic studies. In the present work whole-cell reduction of pentoxifylline [1-(5-oxohexyl)-3,5-dimethylxanthine] to LSF [1-(5R-hydroxyhexyl)-3,5-dimethylxanthine] using Lactobacillus kefiri DSM 20587 was investigated. Glucose or 2-propanol was used as a co-substrate to regenerate the NADPH cofactor. The reaction conditions were optimized. The influence of different concentrations of co-substrates on the yield and enantioselectivity of the biotransformation of pentoxifylline into LSF were tested. Maximum yield (100%) of biotransformation was reached in the presence of glucose as a co-substrate. At glucose concentrations of 675 and 900 mM the bioreduction of pentoxifylline proceeded highly enantioselectively (enantiomeric excess for the R enantiomer of 98%).     

Seasonal biomass allocation in a boreal perennial grass (Phalaris arundinacea L.) under elevated temperature and CO2 with varying water regimes

The aim of this study was to analyze and model how biomass is allocated to the leaves, stems, and roots of perennial grass (reed canary grass, Phalaris arundinacea L., hereafter RCG) under elevated temperature (ET) (+approx. 3 °C) and CO₂ (approx. 700 μmol mol^?1) and with variable groundwater levels (high to low water levels) in a boreal environment. For this purpose, RCG plants were grown in environmentally controlled chambers over two growing seasons (April–September of 2009 and 2010), and the plant organ biomass (leaves, stems, and roots) was measured seven times over the entire growing season. The results showed that biomass production was mainly allocated to the leaves (LMF) and stems (SMF) early in the growing season, to the stems in the middle of the growing season, and to the roots (RMF) later in the growing season. Compared to ambient conditions, ET treatments increased LMF and SMF, and decreased RMF over the growing season under well-water conditions. Under low groundwater level, ET treatments decreased LMF and increased RMF throughout the growing season, and increased SMF in early periods and then decreased later in the growing season. CO₂ enrichment did not significantly affect the seasonal allocation pattern between plant organs. The effect of the groundwater level on biomass allocation was stronger than that of the climatic treatments. In conclusion, plant phenology controlled the seasonal course of biomass allocation in RCG and climatic treatments affected biomass allocation to each of the three plant organs, while the direction and extent of climate-related changes in biomass allocation depended on the availability of groundwater. The influence of groundwater level appeared to be crucial for the carbon gain regarding the production of RCG biomass for energy purpose and the concurrent sequestration of carbon in soils under changing climate in the mire sites used to cultivate RCG.