Exudate Production Research Articles

Plant Latex, from Ecological Interests to Bioactive Chemical Resources.

Historically, latex-bearing plants have been regarded as important medicinal resources in many countries due to their characteristic latex ingredients. They have also often been endowed with a social or cultural significance in religious or cult rituals or for hunting. Initial chemical studies focused on the protein or peptide content but recently the interest extended to smaller molecules. Latex has been found to contain a broad range of specialized metabolites such as terpenoids, cardenolides, alkaloids, and phenolics, which are partly responsible for their antibacterial, antifungal, anthelmintic, cytotoxic, and insect-repellent activities. The diversity in biology and chemistry of latexes is supposedly associated to their ecological roles in interactions with exogenous factors. Latexes contain unique compounds that are different to those found in their bearing plants. Exploring the feasibility of plant latex as a new type of bioactive chemical resource, this review paper covers the chemical characterization of plant latexes, extending this to various other plant exudates. Also, the factors influencing this chemical differentiation and the production, transportation, and chemistry of the latex exudates are described, based on ecological and biochemical mechanisms. We also proposed a latex coagulation model involving 4 general conserved steps. Therefore, the inherent defensive origin of latexes is recognized as their most valuable character and encourages one to pay attention to these materials as alternative sources to discover metabolites with insecticidal or antimicrobial activity.

Ecotoxicity of hallachrome, an unusual 1-2 anthraquinone excreted by the infaunal polychaete Halla parthenopeia: evidence for a chemical defence?

Polychaetes play a prominent role in marine systems, but little is known about their secondary metabolites compared with other benthic taxa. In the present study, we investigated the toxicity of hallachrome, an unusual 1-2 anthraquinone identified from the skin of some polychaetes, including the Mediterranean infaunal species Halla parthenopeia. Under stress conditions, this worm releases a harmful purple mucus, whose noxious compounds were still unknown. We hypothesized that hallachrome also occurs in the purple mucus, giving rise to its color and toxicity. Soon after the production of the purple exudate, H. parthenopeia also secretes a harmless, transparent mucus, which pushes away the toxic one, suggesting protective functions for the worm itself. LC-MS and 1H-NMR analyses confirmed the presence of the pigment hallachrome in the purple mucus. The average concentration of the pigment in the purple mucus was about 310 mg L-1. Ecotoxicological bioassays on representative species of bacteria, protozoans, rotifers, crustaceans (Artemia franciscana) and polychaetes (Dinophilus gyrociliatus) revealed its severe toxic effects: LC50/EC50 values ranged from 0.11-5.67 mg L-1. Hallachrome showed higher toxicity for A. franciscana than other naturally occurring anthraquinones. Tests on encapsulated embryos of D. gyrociliatus evidenced the ability of a mucus layer to limit hallachrome diffusion, confirming the protective role of the transparent mucus. Given the information available on polychaetes anti-predator strategies, hallachrome cannot be considered a consumer deterrent. However its toxicity and wide range of activity suggest chemical defensive functions against potential competitors, parasites and/or pathogens.

Identification of exudates from callus of Mangrove Plant (Rhizophora apiculata BI) in vitro.

Rhizophora apiculata is species in mangrove vegetation. The mangroves leaves were the water-storage type. Induction of callus from the leaf of R. apiculata faced problems, i.e., browning phenomena and exudates. This research aimed to evaluate the production of exudates and their correlation with the browning of explant and to identify kind of compounds of exudates. The leaf that is used as explants was divided into the base and tip section was grown in Murashige and Skoog (MS) medium with the addition of NAA 1 mg/L, BAP 0,3 mg/L, and activated charcoal 12 g / L. The treatments included 24 hours placed in the dark and 24 hours placed under light, 16 hours placed in the dark and 8 hours under the light, 8 hours placed in the dark and 16 hours under the light; the treatments were repeated four times. Respond of explants were descriptively observed, while the exudates were analyzed by Benedict test. The results showed that light treatment could induce callus formation while 24-hour dark treatment could reduce browning. The novelty of this research lies upon the process of browning prevention using light duration treatment. Therefore, browning could be prevented, and mangrove culture could successfully produce callus. Not at all explants produced the exudates. Light treatment can be used to avoid exudates production. Some of the exudates consisted of carbohydrates. Nevertheless, another one consisted of a salt solution. These exudates made a disturbance in callus initiation of R. apiculata.

Ideas and perspectives: Carbon leaks from flooded land: do we need to replumb the inland water active pipe?

Abstract. At the global scale, inland waters are a significant source of atmospheric carbon (C), particularly in the tropics. The active pipe concept predicts that C emissions from streams, lakes and rivers are largely fuelled by terrestrial ecosystems. The traditionally recognized C transfer mechanisms from terrestrial to aquatic systems are surface runoff and groundwater drainage. We present here a series of arguments that support the idea that land flooding is an additional significant process that fuels inland waters with C at the global scale. Whether the majority of CO2 emitted by rivers comes from floodable land (approximately 10 % of the continents) or from well-drained land is a fundamental question that impacts our capacity to predict how these C fluxes might change in the future. Using classical concepts in ecology, we propose, as a necessary step forward, an update of the active pipe concept that differentiates floodable land from drained land. Contrarily to well-drained land, many wetlands (in particular riparian and littoral wetlands) combine strong hydrological connectivity with inland waters, high productivity assimilating CO2 from the atmosphere, direct transfer of litter and exudation products to water and waterlogged soils, a generally dominant allocation of ecosystem respiration (ER) below the water surface and a slow gas-exchange rate at the water–air interface. These properties force plants to pump atmospheric C to wetland waters and, when hydrology is favourable, to inland waters as organic C and dissolved CO2. This wetland CO2 pump may contribute disproportionately to CO2 emissions from inland waters, particularly in the tropics where 80 % of the global CO2 emissions to the atmosphere occur. In future studies, more care must be taken in the way that vertical and horizontal C fluxes are conceptualized along watersheds, and 2-D models that adequately account for the hydrological export of all C species are necessary. In flooded ecosystems, significant effort should be dedicated to quantifying the components of primary production and respiration by the submerged and emerged part of the ecosystem community and to using these metabolic rates in coupled hydrological–biogeochemical models. The construction of a global typology of wetlands that includes productivity, gas fluxes and hydrological connectivity with inland waters also appears necessary to adequately integrate continental C fluxes at the global scale.

Long-term effects of straw and straw-derived biochar on soil aggregation and fungal community in a rice-wheat rotation system.

BackgroundSoil aggregation is fundamental for soil functioning and agricultural productivity. Aggregate formation depends on microbial activity influencing the production of exudates and hyphae, which in turn act as binding materials. Fungi are also important for improving soil quality and promoting plant growth in a symbiotic manner. There is a scarcity of findings comparing the long-term impacts of different yearly double-crop straw return modes (e.g., straw return to the field and straw-derived biochar return to the field) on soil aggregation and fungal community structure in rice–wheat rotation systems.MethodsThe effects of 6-year continuous straw and straw-derived biochar amendment on soil physicochemical properties and the fungal community were evaluated in an intensively managed crop rotation system (rice–wheat). Soil samples of different aggregates (macroaggregates, microaggregates, and silt clay) from four different fertilization regimes (control, CK; traditional inorganic fertilization, CF; straw returned to field, CS; straw-derived biochar addition, CB) were obtained, and Illumina MiSeq sequencing analysis of the fungal internal transcribed spacer gene was performed.ResultsCompared to CF, CS and CB enhanced soil organic carbon, total nitrogen, and aggregation in 0–20 and 20–40 cm soil, with CB exhibiting a stronger effect. Additionally, agrowaste addition increased the mean weight diameter and the geometric diameter and decreased the fractal dimension (p < 0.05). Principal coordinates analysis indicated that fertilization management affected fungal community structure and aggregation distribution. In addition, CS increased fungal community richness and diversity, compared to CK, CB decreased these aspects. Ascomycota, unclassified_k_Fungi, and Basidiomycota were the dominant phyla in all soil samples. At the genus level, CB clearly increased fungi decomposing biosolids (Articulospora in macroaggregates in 0–20 cm soil and Neurospora in macroaggregates in 20–40 cm soil); decreased pathogenic fungi (Monographella in macroaggregates and Gibberella in microaggregates in 0–20 cm soil) and CO2-emission-related fungi (Pyrenochaetopsis in microaggregates and silt clay in 0–40 cm soil) (p < 0.05). Straw and biochar with inorganic fertilizer counteracted some of the adverse effects of the inorganic fertilizer with biochar showing better effects than straw.

Primary Closure of Infected Wound Infested by Fly Larvae—Case Report in Dog

One of the most common aggravating factors of wounds is the myiasis. Flies lay their eggs on the wound, they hatch and release a larval form of the dipteran, which feeds on host tissues leading to necrosis and large production of exudate, thus, it is an extremely pleasant environment to bacterial multiplication. The aim of this study was to describe the case of a dog that displayed an infested larvae ulcerated tumor in the ocular region. Successful results were obtained when performing surgical treatment of the wound with healing by primary closure. The 13-year-old female dog, 30 kg, was brought to the Veterinary Clinic of Ingá University Center, Maringá-PR, Brazil, with the main complaint of an ulcerated left ocular tumor. The owner could not tell when the problem had started. After the patient’s physical and laboratory evaluation, which were within normal parameters, enucleation was scheduled for tumor removal. On the day of surgery, the owner reported large mucopurulent secretion and foul odor at the site. The patient was taken for the larvae removal surgical procedure and later enucleation. The wound was debrided and washed with physiological solution, and then tarsorrhaphy was performed and a Penrose drain was applied. The animal returned 15 days later with the wound fully healed. As a conclusion with the current report, the primary closure treatment with the use of drain after intense debridement of a fly larvae infected wound can be a good alternative, especially when it is aimed at faster healing.

Isolation and Characterization of Plant Metabolite Signals that Induce Type III Secretion by the Plant Pathogen Pseudomonas syringae.

Pseudomonas syringae is a bacterium that can cause disease on a wide range of plant species including important agricultural crops. A primary virulence mechanism used by P. syringae to infect host plants is the type III secretion system (T3SS), a syringe-like structure that delivers defense-suppressing proteins directly into plant cells. Genes encoding the T3SS are not transcribed in P. syringae prior to contact with a potential host plant and must be expressed during initial stages of infection. Specific organic and amino acids exuded by plants were recently identified as signals that can induce expression of T3SS-associated genes. Here we describe a technique to produce exudates from intact Arabidopsis seedlings and evaluate the exudates for the presence of these bioactive metabolites. We provide procedures for exudate production as well as downstream assays to assess T3SS gene expression using a GFP transcriptional reporter. We also describe methods for preparing high-quality protein and RNA from exudate-treated bacteria to directly assess changes in mRNA and protein abundance. These methods could be used to investigate mechanisms regulating P. syringae perception of plant metabolites as well as the release of these substances by the plant, and more generally to investigate host signals perceived by other phytopathogens.

Formation of sclerotia in Sclerotinia ginseng and composition of the sclerotial exudate.

BackgroundSclerotinia ginseng is a major devastating soil-borne pathogen of ginseng that can cause irreparable damage and large economic losses. This pathogen produces sclerotia, which are among the most persistent resting structures produced by filamentous fungi. The production of an exudate is a common feature of sclerotial development.MethodsS. ginseng was cultured on 10 different media and the following parameters were measured: mycelial growth rate (mm/day), initial formation time of exudate droplets, total quantity of exudate, number of sclerotia per dish, and sclerotial fresh/dry weight. The composition of the sclerotial exudate was analyzed using four methods (high performance liquid chromatography, gas chromatography-mass spectrometry, flame atomic absorption spectrometry, and Nessler’s reagent spectrophotometry).ResultsWe found that PDA was the optimal medium for exudate production, while SDA medium resulted in the highest mycelial growth rate. The earliest emergence of exudate droplets from sclerotia was on OA-YE and V8 media. The largest amount of sclerotia and the smallest sclerotia were produced on V8 medium. The maximum and minimum dry/fresh weight were obtained on MEA medium and V8 medium, respectively. The exudate contained organic acids (oxalic acid, gallic acid, ferulic acid, vanillic acid, caffeic acid, and tannic acid), carbohydrates (inositol, glucose, and trehalose), various ions (potassium, sodium, and magnesium), and ammonia.DiscussionThe functions of the identified compounds are discussed within the context of pathogenicity, sclerotial development, and antimicrobial activity. Our findings provide information about the production of sclerotia and the composition of sclerotial exudate that may be useful to develop strategies to control this disease.

Following their tears: Production and use of plant exudates in the Neolithic of North Aegean and the Balkans

Resinous and tarry materials have been valuable commodities since prehistory as their widespread use for numerous purposes indicates, but remain largely neglected by archaeological research, in part due to their poor preservation and the need for chemical analyses to identify them. This paper explores the use of these plant exudates in northern Greece and the Balkans during the Early and Middle Holocene with the aim of documenting the production and use of tarry materials and the exploitation of woodland resources. To this end tarry material found on pottery from 10 neolithic settlements located in North Greece, Bulgaria and Serbia, spanning the Early to Late Neolithic periods (7th to 5th millennia BC), were analysed by gas chromatography-mass spectrometry (GC-MS) and identified using the biomarker approach. Data from analysis of wood charcoal found at Neolithic sites together with the pollen record have also been considered in order to assess the availability of raw materials to local populations. The results of biomolecular analysis show that birch-bark tar was almost exclusively used by Neolithic communities located in the Balkan hinterland, while a more complex picture arises for the northern Aegean area. Here, in addition to the predominant birch-bark tar, pine resin and pitch have also been identified as well as beeswax. The pollen and anthracological record suggest that birch existed in northern Greece and the Balkans hinterland during the Early Holocene, but must have been restricted to the uplands. Procurement of raw material may have taken place, therefore, at some distances from the settlements, involving the movement of people and raw materials or final products within the wider region. Chemical analysis provides evidence for variability in the production of tarry materials between settlements in northern Greece, while in the Balkan interior tar-making appears to have followed a more standardised recipe.

Mechanism of plant mediated methane emission in tropical lowland rice

Methane (CH4) is predominantly produced in lowland rice soil, but its emission from soil to atmosphere primarily depends on passage/conduit or capillary pore spaces present in rice plants. The gas transport mechanism through aerenchyma pore spaces of rice cultivars was studied to explore the plant mediated CH4 emission. Seven rice cultivars, based on the life cycle duration (LCD), were tested in tropical eastern India. Three LCD groups were, (a) Kalinga 1 and CR Dhan 204 (LCD: 110–120 days); (b) Lalat, Pooja and CR 1014 (LCD: 130–150 days); and (c) Durga and Varshadhan (LCD: 160–170 days). Rate of CH4emission, root exudates, root oxidase activities and shoot aerenchyma pore spaces were analyzed to study the mechanism of plant mediated emission from rice. Aerenchyma pore space was quantified in the hypothesis that it regulates the CH4 transportation from soil to atmosphere. The ratio of pore space area to total space was lowest in Kalinga 1 cultivar (0.29) and highest was in Varshadhan (0.43). Significant variations in the methane emission were observed among the cultivars with an average emission rate ranged from 0.86 mg m−2 h−1 to 4.96 mg m−2 h−1. The CH4 emission rates were lowest in short duration cultivars followed by medium and long duration ones. The greenhouse gas intensity considering average CH4 emission rate per unit grain yield was also lowest (0.35) in Kalinga 1 and relatively less in short and medium duration cultivars. Root exudation was higher at panicle initiation (PI) than maximum tillering (MT) stage. Lowest exudation was noticed in (197.2 mg C plant−1 day−1) Kalinga 1 and highest in Varsadhan (231.7 mg C plant−1 day−1). So we can say, the rate of CH4 emission was controlled by aerenchyma orientation, root exudation and biomass production rate which are the key specific traits of a cultivar. Identified traits were closely associated with duration and adaptability to cultivars grown in specific ecology. Therefore, there is possibility to breed rice cultivars depending on ecology, duration and having less CH4 emission potential, which could be effectively used in greenhouse gas mitigation strategies.

Characterization of Nicotiana tabacum genotypes possessing deletion mutations that affect potyvirus resistance and the production of trichome exudates

BackgroundAdvances in genomics technologies are making it increasingly feasible to characterize breeding lines that carry traits of agronomic interest. Tobacco germplasm lines that carry loci designated VAM and va have been extensively investigated due to their association with potyvirus resistance (both VAM and va) and defects in leaf surface compounds originating from glandular trichomes (VAM only). Molecular studies and classical genetic analyses are consistent with the model that VAM and va represent deletion mutations in the same chromosomal region. In this study, we used RNA-seq analysis, together with emerging tobacco reference genome sequence information to characterize the genomic regions deleted in tobacco lines containing VAM and va.ResultsTobacco genotypes TI 1406 (VAM), K326-va and K326 (wild type) were analyzed using RNA-seq to generate a list of genes differentially expressed in TI 1406 and K326-va, versus the K326 control. Candidate genes were localized onto tobacco genome scaffolds and validated as being absent in only VAM, or missing in both VAM and va, through PCR analysis. These results enabled the construction of a map that predicted the relative extent of the VAM and va mutations on the distal end of chromosome 21. The RNA-seq analyses lead to the discovery that members of the cembratrienol synthase gene family are deleted in TI 1406. Transformation of TI 1406 with a cembratrienol synthase cDNA, however, did not recover the leaf chemistry phenotype. Common to both TI 1406 and K326-va was the absence of a gene encoding a specific isoform of a eukaryotic translation initiation factor (eiF4E1.S). Transformation experiments showed that ectopic expression of eiF4E1.S is sufficient to restore potyvirus susceptibility in plants possessing either the va or VAM mutant loci.ConclusionsWe have demonstrated the feasibility of using RNA-seq and emerging whole genome sequence resources in tobacco to characterize the VAM and va deletion mutants. These results lead to the discovery of genes underlying some of the phenotypic traits associated with these historically important loci. Additionally, initial size estimations were made for the deleted regions, and dominant markers were developed that are very close to one of the deletion junctions that defines va.

Biofilm monitoring as a tool to assess the efficiency of artificial reefs as substrates: Toward 3D printed reefs

Habitat destruction is one of the main causes of the decline of biodiversity and of fishery resources in the marine environment. An artificial reef (AR) could be a tool for protecting or restoring these habitats and their declining biodiversity, and also help to enhance sustainable fisheries. The goal is to design non-polluting structures that best mimic the complexity of natural habitats in order to improve their service to the community. To date, the assessment of reef performance has been mostly focused on fish assemblages and species of ecological and/or socio-economic interest, and has disregarded the biofilm communities that determine the first level of an AR’s trophic network. In this work, we used biofilm formation to compare the quality of substrates used as building parts for an AR, in order to optimize an eco-friendly material that will be used to design a new generation of ARs produced by giant 3D printers. The structure of the photosynthetic communities has been identified using pigment biomarkers and their production of exudates has been analysed. These polymeric substances were quantified in terms of total sugar and protein concentrations. They were further analysed in terms of amino acid content. We found no significant differences between the micro-algae communities developed on the different substrates. These photosynthetic communities were mainly composed of diatoms, prasinophytes, haptophytes, and dinoflagellates. However, we showed that the material for ARs is crucial for biofilm development, especially with regard to its secretions of sugar. The choice of an appropriate substrate for AR construction is thus of particular importance since biofilm secretions determine the organic substrate on which sessile macro-organisms will settle.

Aldaulactone - An Original Phytotoxic Secondary Metabolite Involved in the Aggressiveness of Alternaria dauci on Carrot.

Qualitative plant resistance mechanisms and pathogen virulence have been extensively studied since the formulation of the gene-for-gene hypothesis. The mechanisms involved in the quantitative traits of aggressiveness and plant partial resistance are less well-known. Nevertheless, they are prevalent in most plant-necrotrophic pathogen interactions, including the Daucus carota–Alternaria dauci interaction. Phytotoxic metabolite production by the pathogen plays a key role in aggressiveness in these interactions. The aim of the present study was to explore the link between A. dauci aggressiveness and toxin production. We challenged carrot embryogenic cell cultures from a susceptible genotype (H1) and two partially resistant genotypes (I2 and K3) with exudates from A. dauci strains with various aggressiveness levels. Interestingly, A. dauci-resistant carrot genotypes were only affected by exudates from the most aggressive strain in our study (ITA002). Our results highlight a positive link between A. dauci aggressiveness and the fungal exudate cell toxicity. We hypothesize that the fungal exudate toxicity was linked with the amount of toxic compounds produced by the fungus. Interestingly, organic exudate production by the fungus was correlated with aggressiveness. Hence, we further analyzed the fungal organic extract using HPLC, and correlations between the observed peak intensities and fungal aggressiveness were measured. One observed peak was closely correlated with fungal aggressiveness. We succeeded in purifying this peak and NMR analysis revealed that the purified compound was a novel 10-membered benzenediol lactone, a polyketid that we named ‘aldaulactone’. We used a new automated image analysis method and found that aldaulactone was toxic to in vitro cultured plant cells at those concentrations. The effects of both aldaulactone and fungal organic extracts were weaker on I2-resistant carrot cells compared to H1 carrot cells. Taken together, our results suggest that: (i) aldaulactone is a new phytotoxin, (ii) there is a relationship between the amount of aldaulactone produced and fungal aggressiveness, and (iii) carrot resistance to A. dauci involves mechanisms of resistance to aldaulactone.

A cost-effectiveness analysis of a hydration response technology dressing in the treatment of venous leg ulcers in the UK.

Venous leg ulcers (VLUs) cause significant pain and suffering for patients. Additionally, they place considerable financial and service burden on the National Health Service (NHS). A large proportion of VLUs do not heal within the standard time frame of 16-24 weeks, resulting in static wounds which commonly have issues with increasing exudate production. As the NHS continues to face times of austerity, services need to find solutions to be able to reduce costs and release nursing time while maintaining standards of care. Cutimed Sorbion Sachet S, a hydration response technology dressing (HRTD), is a treatment option for the management of patients with a VLU. The objective of this study was to provide an update of the health economic analysis of HRTD in comparison with relevant comparators in the UK with current cost data. HRTD was compared against four different dressings, Zetuvit Plus (a super absorbent polymer dressing SAP), DryMax extra (a superabsorbent dressing, SADM), KerraMax Care (superabsorbent dressing, SAKM) and Eclypse (superabsorbent dressing, SAE) from a cost-effectiveness perspective. Clinical data were derived from literature and expert opinion. Cost input was utilised based on publicly available data and literature. The average patient in the model is assumed to be 65 years with a diagnosed VLU. It is assumed that patients in the different treatment arms have the same background mortality, hence the endpoint mortality is not included in the model. The analysis is based on a deterministic Markov model derived from Harding et al. with weekly cycles. The following assumptions are made: first, all patients start in a static health state with a non-healed but non-progressing VLU. It is assumed in the model that patients wounds can transition to a deteriorating state or one where a wound is improving or could progress. Additionally, VLUs could be healed from a progressed wound (i.e. improved wound), or they could develop into a severe wound with complications (infections) to be treated in hospitals. The time frame for the analysis was fixed for one year and no re-occurence after healing was assumed to happen. The cost-effectiveness analysis demonstrates health economic dominance of HRDT being more effective and cost-saving against all analysed comparators. When using literature-based input values, the incrementally higher healing rates for HRDT are 11.04 months (versus SAP), 29.04 months (versus SADM), 1.68 months (versus SAKM) and 11.04 months (versus SAE). Cost savings per patient were £37.60 versus SAP, £171.68 versus SADM, £3.13 versus SAKM and £43.63 versus SAE. Clinical benefits and cost savings increase when real-life practice assumptions, based on expert opinion, are included. Based on the underlying health economic model, HRDT is more effective and less costly than other comparative products in VLUs in the UK.

Gene Expression Profiling of Iron Deficiency Chlorosis Sensitive and Tolerant Soybean Indicates Key Roles for Phenylpropanoids under Alkalinity Stress.

Alkaline soils comprise 30% of the earth and have low plant-available iron (Fe) concentration, and can cause iron deficiency chlorosis (IDC). IDC causes soybean yield losses of $260 million annually. However, it is not known whether molecular responses to IDC are equivalent to responses to low iron supply. IDC tolerant and sensitive soybean lines provide a contrast to identify specific factors associated with IDC. We used RNA-seq to compare gene expression under combinations of normal pH (5.7) or alkaline pH (7.7, imposed by 2.5 mM bicarbonate, or pH 8.2 imposed by 5 mM bicarbonate) and normal (25 μM) or low (1 μM) iron conditions from roots of these lines. Thus, we were able to treat pH and Fe supply as separate variables. We also noted differential gene expression between IDC sensitive and tolerant genotypes in each condition. Classical iron uptake genes, including ferric-chelate reductase (FCR) and ferrous transporters, were upregulated by both Fe deficiency and alkaline stress, however, their gene products did not function well at alkaline pH. In addition, genes in the phenylpropanoid synthesis pathway were upregulated in both alkaline and low Fe conditions. These genes lead to the production of fluorescent root exudate (FluRE) compounds, such as coumarins. Fluorescence of nutrient solution increased with alkaline treatment, and was higher in the IDC tolerant line. Some of these genes also localized to previously identified QTL regions associated with IDC. We hypothesize that FluRE become essential at alkaline pH where the classical iron uptake system does not function well. This work could result in new strategies to screen for IDC tolerance, and provide breeding targets to improve crop alkaline stress tolerance.

Planting exotic relatives has increased the threat posed by Dothistroma septosporum to the Caledonian pine populations of Scotland.

To manage emerging forest diseases and prevent their occurrence in the future, it is essential to determine the origin(s) of the pathogens involved and identify the management practices that have ultimately caused disease problems. One such practice is the widespread planting of exotic tree species within the range of related native taxa. This can lead to emerging forest disease both by facilitating introduction of exotic pathogens and by providing susceptible hosts on which epidemics of native pathogens can develop. We used microsatellite markers to determine the origins of the pathogen Dothistroma septosporum responsible for the current outbreak of Dothistroma needle blight (DNB) on native Caledonian Scots pine (Pinus sylvestris) populations in Scotland and evaluated the role played by widespread planting of two exotic pine species in the development of the disease outbreak. We distinguished three races of D. septosporum in Scotland, one of low genetic diversity associated with introduced lodgepole pine (Pinus contorta), one of high diversity probably derived from the DNB epidemic on introduced Corsican pine (Pinus nigra subsp. laricio) in England and a third of intermediate diversity apparently endemic on Caledonian Scots pine. These races differed for both growth rate and exudate production in culture. Planting of exotic pine stands in the UK appears to have facilitated the introduction of two exotic races of D. septosporum into Scotland which now pose a threat to native Caledonian pines both directly and through potential hybridization and introgression with the endemic race. Our results indicate that both removal of exotic species from the vicinity of Caledonian pine populations and restriction of movement of planting material are required to minimize the impact of the current DNB outbreak. They also demonstrate that planting exotic species that are related to native species reduces rather than enhances the resilience of forests to pathogens.

Introducing a new superabsorbent dressing to manage wound exudate.

The production of wound exudate is a natural and normal consequence of healing. However, when the constituents, volume and consistency of the exudate alter, problems can occur. This article discusses the different types of exudate and its impact on both the patient and the clinician and outlines appropriate exudate assessment and effective management and dressing selection. If these are performed appropriately, this can improve quality of life for the patient and save time and money for healthcare providers.

Seasonal Shifts in Bacterial Community Responses to Phytoplankton-Derived Dissolved Organic Matter in the Western Antarctic Peninsula.

Bacterial consumption of dissolved organic matter (DOM) drives much of the movement of carbon through the oceanic food web and the global carbon cycle. Understanding complex interactions between bacteria and marine DOM remains an important challenge. We tested the hypothesis that bacterial growth and community succession would respond differently to DOM additions due to seasonal changes in phytoplankton abundance in the environment. Four mesocosm experiments were conducted that spanned the spring transitional period (August–December 2013) in surface waters of the Western Antarctic Peninsula (WAP). Each mesocosm consisted of nearshore surface seawater (50 L) incubated in the laboratory for 10 days. The addition of DOM, in the form of cell-free exudates extracted from Thalassiosira weissflogii diatom cultures led to changes in bacterial abundance, production, and community composition. The timing of each mesocosm experiment (i.e., late winter vs. late spring) influenced the magnitude and direction of bacterial changes. For example, the same DOM treatment applied at different times during the season resulted in different levels of bacterial production and different bacterial community composition. There was a mid-season shift from Collwelliaceae to Polaribacter having the greatest relative abundance after incubation. This shift corresponded to a modest but significant increase in the initial relative abundance of Polaribacter in the nearshore seawater used to set up experiments. This finding supports a new hypothesis that starting community composition, through priority effects, influenced the trajectory of community succession in response to DOM addition. As strong inter-annual variability and long-term climate change may shift the timing of WAP phytoplankton blooms, and the corresponding production of DOM exudates, this study suggests a mechanism by which different seasonal successional patterns in bacterial communities could occur.

Wallemia peruviensis sp. nov., a new xerophilic fungus from an agricultural setting in South America.

We obtained four isolates of the xerophilic genus Wallemia from the rooftop of a house made of red brick and cement in an agronomic field planted with common beans and maize in Pachacamac, Lima, Peru. Bayesian phylogenetic analysis with rDNA gene sequences showed these Wallemia isolates form a distinct and strongly supported clade closely related to W. hederae. We examined the macro and micromorphology, growth rate and production of exudates of isolates on media containing different amounts of glucose and NaCl (water activity from 0.9993 to 0.8480). Their chaotropic and kosmotropic tolerance were tested on media with multiple molar concentrations of MgCl2 and MgSO4 (water activity from 0.9880 to 0.7877). Isolates are xerophilic and halotolerant, growing on 17% NaCl-supplemented media (water activity=0.8480). Maximum concentrations of MgCl2 and MgSO4 at which growth was observed were 1.7 and 3.5M, respectively. Isolates were shown to represent a novel species, described as Wallemia peruviensis sp. nov. In contrast to W. hederae, W. peruviensis does not produce exudates on malt extract agar+17% NaCl media. An updated dichotomous key to Wallemia species is provided. This is the first new species of Wallemia described from South America and the first association of a Wallemia species with an agricultural environment on this continent.

Expression of MMP-8 in Pressure Injuries in Spinal Cord Injury Patients Managed by Negative Pressure Wound Therapy or Conventional Wound Care: A Randomized Controlled Trial.

The purpose of this study was to assess the level of matrix metalloproteinase-8 (MMP-8) and wound-healing outcome measures (length, width, and depth, exudate amount, and tissue type) in pressure injuries (PIs) of spinal cord-injured patients treated with negative pressure wound therapy (NPWT) using a novel negative pressure device versus PI treated with wet to moist gauze (conventional wound care). Randomized controlled trial. Forty-four spinal cord-injured patients with stage 3 and 4 sacral PI participated in the study. The study setting was the Department of Orthopedic Surgery at King George's Medical University, in Lucknow, India. Twenty two subjects were randomly allocated to undergo NPWT via a novel negative pressure device, and 22 participants received conventional wound dressing (wet to moist gauze dressings). Pressure injuries were treated for 9 weeks or until wound closure. Levels of MMP-8 were analyzed in the tissues of PIs at weeks 0, 3, 6, and 9 by enzyme-linked immunosorbent assay. Significantly lower levels of MMP-8 were observed in the NPWT group at week 6 and week 9. There were no significant changes in the length and width of PIs between the groups till week 3. Significant reduced length and width were observed in PIs of patients in the NPWT group at week 6 (P = .04) and week 9 (P = .001). Similarly, significant reduction in the depth of PIs was observed in the NPWT group at week 9 (P < .05). At the end of 9 week, levels of MMP-8 showed a positive correlation with reduction in the length, width, and depth of PIs in the NPWT group while in the conventional dressing group, negative correlation was observed in association with MMP-8 and the length, width, and depth of PIs. Exudate levels were significantly lower in the NPWT group compared with the conventional dressing group from week 3 (2.96 ± 0.21 vs 2.62 ± 0.49); this difference persisted through week 9 (1.35 ± 0.75 vs 0.14 ± 0.35). Conversion of slough into red granulation tissue was significantly higher in the NPWT group after week 6 (P = .001). Reduced levels of MMP-8 and an increased rate of healing were found in patients allocated to treatment with a novel negative pressure device as compared to wet to moist gauze conventional dressing. The novel NPWT device used in this study reduced exudate production and enhanced the rate of formation of red granulation tissue.