Risk assessment of Aphanomyces euteiches root rot disease: quantification of low inoculum densities in field soils using droplet digital PCR

European Journal of Plant Pathology - Fusarium verticillioides is a soil-borne plant pathogen of maize plants (Zea mays L.) responsible for major yield losses by causing root, stalk, and ear rot...     

Die Veränderungen der Gehalte an essentiellen Aminosäuren während der Reifung des Weizenkorns

Changes in the contents of main aminoacids have been watched during the period of wheat ripening. The aminoacids have been determined by microbiological methods. The results obtained have been calculated according to the statistics used in British Pharmacopeia. Reliability range has been settled for each results separately. Determination fault amounts to ±4,6% on an average. The total aminoacids have been calculated to 16% nitrogen. According to analysis results the aminoacids can be classified in four groups, i.e.:

1. Aminoacids which share in total proteins remain constant during wheat ripening: Threonine, Valine, Isoleucine.
2. Aminoacids which share in total proteins decrease during wheat ripening: Lysine.
3. Aminoacids which share in total proteins increase during wheat ripening: Methionine, Arginine, Tryptophane.
4. Aminoacids whose contents show no regularity during the wheat ripening: Leucine, Histidine, Phenylalanine.

     

Zn, Cu, Cd and Hg binding to metallothioneins in harbour porpoises Phocoena phocoena from the southern North Sea

Background  

Harbour porpoises Phocoena phocoena from the southern North Sea are known to display high levels of Zn and Hg in their tissues linked to their nutritional status (emaciation). The question arises regarding a potential role of metallothioneins (MTs) with regard to these high metal levels. In the present study, metallothionein detection and associated Zn, Cd, Cu and Hg concentrations were investigated in the liver and kidney of 14 harbour porpoises collected along the Belgian coast.     

Identification,pathogenicity and community dynamics of fungi and oomycetes associated with pea root rot in northern France

The pea root rot complex is a major concern for green pea production worldwide. This study aimed at characterizing its composition and dynamics throughout a cropping season in northern France. To this end, fungi and oomycetes were isolated from green pea plant roots with symptoms sampled at the flowering stage in 22 fields in 2017, and at the pea emergence, elongation and flowering stages in two fields in 2018. Out of 646 isolates collected, 317 were identified using molecular markers. Fusarium oxysporum, F. solani and F. redolens were highly predominant. Pathogenicity tests separated the isolates into four aggressiveness groups. F. solani isolates were the most aggressive. Phylogenetic analysis of their TEF1 sequences showed that they mainly belonged to the F. pisi lineage, and that F. oxysporum isolates were genetically close to isolates from the UK that did not belong to the forma specialis pisi. In addition, several Clonostachys rhizophaga isolates are reported for the first time to cause pea root rot. The oomycetes were rarely found and were represented by a few Pythium spp. isolates. Lastly, this study shows that the fungal and oomycete communities associated with pea root rot change during the cropping season. The level of dissimilarity of the root-rot-associated communities decreased throughout the cropping season towards a more similar composition at the flowering stage, dominated by F. solani, F. oxysporum and F. redolens. The proportion of nonpathogenic to weakly pathogenic isolates decreased progressively during the growing season in favour of moderately to highly pathogenic isolates.     

A correlation network approach to metabolic data analysis for tomato fruits

Network analysis of correlations between abundances of metabolites across tomato genotypes can help in unraveling the biological basis of organoleptic variation in tomato. We illustrate how to construct and interpret simple correlations networks using metabolic data collected on a diverse set of tomato genotypes. Various types of correlations are calculated and displayed in the form of networks. Interpretations on the basis of network analyses are compared to interpretations following principal components analysis.     

毛竹节间材与节部材的构造与强度差异研究

竹节是竹子为适应其生存环境长期择优演化而形成的特殊构造,它对提高细长竹子的刚度与稳定性至关重要。但在竹的利用中,竹节对竹材的力学强度是否会有影响,说法不一。现以毛竹为研究对象,在比较了竹节间材和竹节之间的构造差异的基础上,以竹青、竹黄、竹节未处理和已刨平处理的两种试件形式,分析研究了毛竹的含节材与不含节的节间材在强度上的差异。结果表明,无论是自然状态下的竹材试件,还是刨去刨平青、黄、节的竹材试件,竹节对弯曲强度、顺纹剪切强度、抗压强度等力学性能均未见有降低的作用,相反还有着不同程度的增强作用。但竹节对竹材顺纹抗拉强度有着不可忽视的降低影响。     

Antimicrobial peptides and proteins of the horse - insights into a well-armed organism

ABSTRACT: Antimicrobial peptides play a pivotal role as key effectors of the innate immune system in plants and animals and act as endogenous antibiotics. The molecules exhibit an antimicrobial activity against bacteria, viruses, and eukaryotic pathogens with different specificities and potencies depending on the structure and amino-acid composition of the peptides. Several antimicrobial peptides were comprehensively investigated in the last three decades and some molecules with remarkable antimicrobial properties have reached the third phase of clinical studies. Next to the peptides themselves, numerous organisms were examined and analyzed regarding their repertoire of antimicrobial peptides revealing a huge number of candidates with potencies and properties for future medical applications. One of these organisms is the horse, which possesses numerous peptides that are interesting candidates for therapeutical applications in veterinary medicine. Here we summarize investigations and knowledge on equine antimicrobial peptides, point to interesting candidates, and discuss prospects for therapeutical applications.     

Spatial variability of nutrient stocks in the humus and soils of a forest massif (Fougères, France)

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).     

Influence of waterlogging on carbon stock variability at hillslope scale in a beech forest (Fougères forest — West France)

The Kyoto protocol [39] directs the signatory countries including France to establish an inventory of carbon stocks in forests. Precise estimates of carbon stocks are hampered by local spatial variability, in particular in wetland areas [25]. The aims of this work are: (i) to estimate the spatial variability of carbon stocks on two hillslopes presenting respectively, a transition between a well-drained zone and a wetland area over a short-distance, and a very progressive transition; (ii) to correlate this variability with soil waterlogging and topographic variations and (iii) to evaluate carbon stock prediction by modelling waterlogging intensity as soil organic carbon (SOC) stocks increase significantly with waterlogging. However, SOC stocks in redoximorphic soils are highly variable, particularly in zones where carbon is redistributed due to erosion and sedimentation. In the litter and the vegetation, the age and density of the stand are the main explanatory factors of C variability. Topographic modelling of the waterlogging intensity could improve the spatial estimation of SOC stocks but not of the C stocks in the humus and vegetation.     

Characterisation of sunflower root colonisation by <Emphasis Type="Italic">Phoma macdonaldii</Emphasis>

Phoma macdonaldii, the causal agent of black stem disease of sunflower (Helianthus annuus), also attacks roots and collars of the plants, resulting in early death. Totally resistant lines do not exist for infection of the aerial parts, but tolerant lines have been characterised. This paper presents a study on colonisation of a partially resistant and a susceptible sunflower line by P. macdonaldii. The fungus was transformed with a constitutively expressed reporter gene encoding the jellyfish green fluorescent protein via Agrobacterium tumefaciens, and colonisation of sunflower roots by this transformed strain was studied by various microscopy techniques including confocal and scanning electron microscopy. The results show that penetration of the fungus into the root occurred through natural fissures or through the epidermis and was similar in both lines. In contrast, the colonisation rate of the stele was reduced in the partially resistant line, and the morphology of the fungal hyphae was also affected. The effect on hyphal morphology was strongest in the stele, indicating a localised production of defence compounds in this line.