Pre-symptomatic detection of <Emphasis Type="Italic">Plasmopara viticola</Emphasis> infection in grapevine leaves using chlorophyll fluorescence imaging

Plasmopara viticola is an economically important pathogen of grapevine. Early detection of P. viticola infection can lead to improved fungicide treatment. Our study aimed to determine whether chlorophyll fluorescence (Chl-F) imaging can be used to reveal early stages of P. viticola infection under conditions similar to those occurring in commercial vineyards. Maximum (F_V/F_M) and effective quantum yield of photosystem II (Φ_PSII) were identified as the most sensitive reporters of the infection. Heterogeneous distribution of F_V/F_M and Φ_PSII in artificially inoculated leaves was associated with the presence of the developing mycelium 3 days before the occurrence of visible symptoms and 5 days before the release of spores. Significant changes of F_V/F_M and Φ_PSII were spatially coincident with localised spots of inoculation across the leaf lamina. Reduction of F_V/F_M was restricted to the leaf area that later yielded sporulation, while the area with significantly lower Φ_PSII was larger and probably reflected the leaf parts in which photosynthesis was impaired. Our results indicate that Chl-F can be used for the early detection of P. viticola infection. Because P. viticola does not expand systemically in the host tissues and the effects of infection are localised, Chl-F imaging at high resolution is necessary to reveal the disease in the field.     

Temporal and spatial variability of enantiomeric fractions (EFs) of chiral organochlorines in relation to soil properties

Purpose

The scope of this article was to investigate the spatial and temporal variability of enantiomeric fractions (EFs) of persistent organic pollutants (POPs) in soil compared to the uncertainty of the analytical data.

Materials and methods

Soil samples were taken with high spatial resolution at two sites in Czech Republic in 2008 to investigate variability on a small spatial scale. In addition, composite soil samples were taken from ten sites in 2005 and 2008 to investigate temporal variations. All samples were analysed for a suite of soil properties as well as concentrations and EFs of polychlorinated biphenyl (PCB) -95, PCB-132 and PCB-149; α-hexachlorocyclohexane (HCH); o,p′-dichlorodiphenyltrichloroethane (DDT); and o,p′-dichlorodiphenyldichloroethane (DDD).

Results and discussion

Median EFs of PCB-95 and PCB-149, α-HCH, o,p′-DDT and o,p′-DDD did not change significantly on the sites sampled in 2005 and again in 2008, while PCB-132 changed from EF?=?0.38 to EF?=?0.53. The sampling methodology is therefore very important, and composite samples will not be the best option if enantioselective degradation processes are investigated. Non-racemic EFs of POPs in the subsampled sites in 2008 were correlated to soil parameters, such as total organic carbon (TOC), total nitrogen and humic acids. These parameters are site specific and might vary on a small scale. This can explain why certain soil parameters are reported as significantly correlated with non-racemic EFs of chiral POPs in some studies, but not always in other similar studies.

Conclusions

While composite samples may still represent the overall prevailing EF range, they are not ideally suited to study enantiomeric degradation processes, which are taking place at a relative small scale, depending on the heterogeneity of soil parameters such as TOC, total organic nitrogen (TON) and humic acids.

     

Coordinated Effects Monitoring and Modelling for Developing and Supporting International Air Pollution Control Agreements

For 20 years the Convention on Long-range Transboundary Air Pollution has worked to control air pollutant emissions in Europe and North America. Its Working Group on Effects (WGE) has been responsible for much of the underpinning science. The WGE's six International Cooperative Programmes (ICPs) on Waters, Natural Vegetation and Crops, Forests, Materials and Cultural Heritage, Integrated Monitoring, and Modelling and Mapping, together with a Joint Task Force on Human Health with WHO, quantify air pollution effects on the environment through monitoring, modelling and scientific review. Early work found evidence to support the need for decreases in emissions of sulphur and nitrogen pollutants. More recently, monitoring results and models have provided the scientific basis, e.g. critical loads and levels, for effects-based Protocols and for evaluating their effectiveness. ICP studies on trends show recovery from acidification effects in keeping with the fall in sulphur emissions. Steady-state models provide an indication of long-term improvements. Recent increased emphasis on developing dynamic models will enable better links between recovery rates and abatement strategies. The scientific network of the ICPs and the monitoring and modelling results have been key to the development of the Convention and are an essential component for its success in the future.     

Protein Heterogeneity in European Wheat Landraces and Obsolete Cultivars: Additional Information II

The endosperm storage protein of 46 European wheat (Triticum aestivum L.) landraces and obsolete cultivars have been fractionated by SDS-PAGE to determine the composition of high molecular weight glutenin subunits (HMW-GS) composition. It has been discovered that about 46% of the wheats were heterogeneous, comprising 2–11 different glutenin profiles. Eighteen of them were observed to be homogeneous. A total of 13 HMW-GS alleles, including 3 at the Glu-A1, 8 at the Glu-B1, and 3 at the Glu-D1 loci were revealed. HMW-GS null controlled by locus Glu-A1, subunits 7 + 8 by Glu-B1, and 2 + 12 by Glu-D1 predominated. However low frequented alleles such as 17 + 18, 20, 6, and 7 were observed. Furthermore, other new alleles encoding HMW-GS at the locus Glu-B1 have been found in one of France cultivar (Saumur d’Automne). The glutenin-based quality score ranged from 4 to 10.     

Nematode assemblages indicate soil restoration on colliery spoils afforested by planting different tree species and by natural succession

Soil nematodes were studied in 28 afforested sites on clay colliery spoil from opencast mining in the Czech Republic. The afforestations had four replicate sites and were represented by 20–33-year-old plantations of oak, alder, linden, spruce, larch, pine, and sites left to natural succession. The total abundance of nematodes in deciduous plantations plus natural successions was 1156 × 10³ ind/m² and in coniferous plantations 1236 × 10³ ind/m². The abundance of plant parasites and omnivores was significantly greater in deciduous than in coniferous plantations. The abundance of root–fungal feeders dominated by Filenchus was greater in spruce and pine plantations than in deciduous plantations. Bacterivorous Plectus predominated in larch plantations. Nematode assemblages in deciduous plantations had significantly greater numbers of species and genera, H’gen, MI, ΣMI, EI and SI values, and greater proportions of omnivores plus predators to other trophic groups than the assemblages in coniferous plantations. The nematode fauna indicated most advanced soil restoration on spoils under oak and alder plantations, intermediate under linden and spruce, and least under pine and larch. Nevertheless, some nematodes typical for developed forests were either found in low population densities (e.g. Teratocephalus) or were missing (e.g. Malenchus).