Influence of nutrient and metal concentration on root exudation under waterlogged conditions

The worldwide energy demand constantly increases and the search for regenerative alternatives is inevitable. A concept that exploits a bioenergy source in situ is the plant Microbial fuel cell (MFC). The plant-MFC uses the natural interplay between electrogenic bacteria in soil and plants to convert solar energy into green electricity. The interplay between bacteria and plant is based on the rhizodeposition of organic compounds into the rhizosphere. It is known, that low phosphate (P) content in the soil as well as a high Aluminum (Al) concentration can induce an enhanced exudation of organic compounds by plants into the rhizosphere. However, so far little is known about the factors that influence the rhizodeposition under waterlogged conditions. Thus, the aim of this study was to increase the exudation of several plants into the rhizosphere under waterlogged conditions by treating the plants with low P content or Al addition. Total organic carbon and inorganic carbon analyses indicated that a reduction of P supply induced a twofold increased release of organic compounds in waterlogged Spartina anglica, a threefold in Hemarthria altissima and a fivefold in Glyceria maxima plants. In contrast, the addition of Al did not affect the root exudation of any screened plant species. It is likely, that the screened plants use other mechanisms to detoxify the Al in the nutrient solution such as absorption into the symplasm or pH modifications of the rhizosphere. In future studies it should be tested, if a reduction of P in the plant-MFC is a possible tool to increase the productivity of the plant- MFC without affecting plant development and health

Accelerating root system phenotyping of seedlings through a computer-assisted processing pipeline

Background: There are numerous systems and techniques to measure the growth of plant roots. However, phenotyping large numbers of plant roots for breeding and genetic analyses remains challenging. One major difficulty is to achieve high throughput and resolution at a reasonable cost per plant sample. Here we describe a cost-effective root phenotyping pipeline, on which we perform time and accuracy benchmarking to identify bottlenecks in such pipelines and strategies for their acceleration. Results: Our root phenotyping pipeline was assembled with custom software and low cost material and equipment. Results show that sample preparation and handling of samples during screening are the most time consuming task in root phenotyping. Algorithms can be used to speed up the extraction of root traits from image data, but when applied to large numbers of images, there is a trade-off between time of processing the data and errors contained in the database. Conclusions: Scaling-up root phenotyping to large numbers of genotypes will require not only automation of sample preparation and sample handling, but also efficient algorithms for error detection for more reliable replacement of manual interventions

Value of ultrasonography as a marker of early response to abatacept in patients with rheumatoid arthritis and an inadequate response to methotrexate: results from the APPRAISE study

Objectives: To study the responsiveness of a combined power Doppler and greyscale ultrasound (PDUS) score for assessing synovitis in biologic-naïve patients with rheumatoid arthritis (RA) starting abatacept plus methotrexate (MTX). Methods: In this open-label, multicentre, single-arm study, patients with RA (MTX inadequate responders) received intravenous abatacept (∼10 mg/kg) plus MTX for 24 weeks. A composite PDUS synovitis score, developed by the Outcome Measures in Rheumatology–European League Against Rheumatism (OMERACT–EULAR)-Ultrasound Task Force, was used to evaluate individual joints. The maximal score of each joint was added into a Global OMERACT–EULAR Synovitis Score (GLOESS) for bilateral metacarpophalangeal joints (MCPs) 2–5 (primary objective). The value of GLOESS containing other joint sets was explored, along with clinical efficacy. Results: Eighty-nine patients completed the 24-week treatment period. The earliest PDUS sign of improvement in synovitis was at week 1 (mean change in GLOESS (MCPs 2–5): −0.7 (95% CIs −1.2 to −0.1)), with continuous improvement to week 24. Early improvement was observed in the component scores (power Doppler signal at week 1, synovial hyperplasia at week 2, joint effusion at week 4). Comparable changes were observed for 22 paired joints and minimal joint subsets. Mean Disease Activity Score 28 (C reactive protein) was significantly reduced from weeks 1 to 24, reaching clinical meaningful improvement (change ≥1.2) at week 8. Conclusions: In this first international prospective study, the composite PDUS score is responsive to abatacept. GLOESS demonstrated the rapid onset of action of abatacept, regardless of the number of joints examined. Ultrasound is an objective tool to monitor patients with RA under treatment. Trial registration number: NCT00767325

An automated, cost-effective and scalable, flood-and-drain based root phenotyping system for cereals

Background: Genetic studies on the molecular mechanisms of the regulation of root growth require the characterisation of a specific root phenotype to be linked with a certain genotype. Such studies using classical labour-intensive methods are severely hindered due to the technical limitations that are associated with the impeded observation of the root system of a plant during its growth. The aim of the research presented here was to develop a reliable, cost-effective method for the analysis of a plant root phenotype that would enable the precise characterisation of the root system architecture of cereals. Results: The presented method describes a complete system for automatic supplementation and continuous sensing of culture solution supplied to plants that are grown in transparent tubes containing a solid substrate. The presented system comprises the comprehensive pipeline consisting of a modular-based and remotely-controlled plant growth system and customized imaging setup for root and shoot phenotyping. The system enables an easy extension of the experimental capacity in order to form a combined platform that is comprised of parallel modules, each holding up to 48 plants. The conducted experiments focused on the selection of the most suitable conditions for phenotyping studies in barley: an optimal size of the glass beads, diameters of the acrylic tubes, composition of a medium, and a rate of the medium flow. Conclusions: The developed system enables an efficient, accurate and highly repeatable analysis of the morphological features of the root system of cereals. Because a simple and fully-automated control system is used, the experimental conditions can easily be normalised for different species of cereals. The scalability of the module-based system allows its capacity to be adjusted in order to meet the requirements of a particular experiment

Observations of the Ushant front displacements with MSG/SEVIRI derived sea surface temperature data

International audienceHourly Sea Surface Temperature (SST) fields derived from the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) onboard Meteosat Second Generation (MSG) are frequently used in studies of the diurnal cycle of the ocean. In this article, we focus on high frequency SST variability induced by tidal currents in the Iroise Sea, west of Brittany (France). This region is known for its strong tidal currents that are responsible in summer for the generation of an intense thermal front, the Ushant front. We use hourly MSG/SEVIRI derived SST to compute the displacements of this front. In the northern part of the front, at 48.75°N, we show that the longitudinal displacements of the front on subdiurnal time scales can be explained by the Lagrangian advection induced by surface currents.We also present maps of surface currents computed from hourly SEVIRI derived SST data using the Maximum Cross Correlation (MCC) method. Comparison of SEVIRI derived velocities with velocities obtained with high frequency (HF) radar measurements and a hindcast numerical simulation (Mercator Ocean) gives encouraging results in the northern part of the Ushant front, near the Ushant Island. Within that region, the mean bias of the SEVIRI velocities was below 0.12 m·s− 1, with the standard deviation ranging from 0.26 m·s− 1 during moderate tides to 0.49 m·s− 1 during spring tides. Further offshore, where the surface thermal structures are weaker and the SST more homogeneous, currents derived using the MCC method were overestimated by 0.3 m·s− 1 and showed larger error standard deviations