Transnational European research collaboration to tackle plant health threats: Euphresco and its contribution to the new EU Plant Health Regulation

The new EU Plant Health Regulation published in December 2016 is intended to modernize the EU plant health regime and to address the challenges posed by globalization of trade and climate change, overcoming the limits of the previous Directive. The main weaknesses of the approach taken so far are linked to the discontinuous links between phytosanitary policy (determined at EU level) and research supporting such a policy, implemented at country level. Since 2006 Euphresco has developed a platform for research coordination that supports capacity building and streamlines the delivery and use of research evidence to support plant health policy. The paper provides an opinion on how Euphresco (research) activities could support the implementation of the new EU Plant Health Regulation.     

The violent collisional history of asteroid 4 Vesta

Vesta is a large differentiated rocky body in the main asteroid belt that accreted within the first few million years after the formation of the earliest solar system solids. The Dawn spacecraft extensively imaged Vesta's surface, revealing a collision-dominated history. Results show that Vesta's cratering record has a strong north-south dichotomy. Vesta's northern heavily cratered terrains retain much of their earliest history. The southern hemisphere was reset, however, by two major collisions in more recent times. We estimate that the youngest of these impact structures, about 500 kilometers across, formed about 1 billion years ago, in agreement with estimates of Vesta asteroid family age based on dynamical and collisional constraints, supporting the notion that the Vesta asteroid family was formed during this event.     

Broad antifungal activity of β-isoxazolinonyl-alanine,a non-protein amino acid from roots of pea (Pisum sativum L.) seedlings

Summary -(Isoxazolin-5-on-2-yl)-alanine (IA), a heterocyclic non-protein amino acid from root extracts and root exudates of pea seedlings, acts as a potent growth inhibitor of several eukaryotic organisms, including yeasts, phytopathogenic fungi, unicellular green algae, and higher plants. The antibiotic effect on baker's yeast was reversed by l-methionine, l-cysteine, and l-homocysteine. Phytopathogenic fungi such as Botrytis cinerea, Pythium ultimum, and Rhizoctonia solani grown on agar containing IA were inhibited in the growth of mycelia or in the production of sclerotia. In contrast, no significant inhibition of either Gram-positive or Gram-negative bacteria was observed. Rhizobium leguminosarum, the compatible microsymbiont of Pisum spp., and Rhizobium meliloti were able to tolerate up to 2.9 mM IA (500 ppm) without any effect on the growth rate. Bradyrhizobium japonicum even gave a positive chemotactic response to IA. The ecological significance of IA as a preformed plant protectant during the seedling stage of Pisum spp. and other IA-containing legumes is discussed.     

Assay system for measurement of denitrification-N loss from ornamental plants potted in peat substrate

An assay system was evaluated for denitrification measurement with potted ornamental plants cultivated in peat substrate (Pelargonium zonale, Euphorbia pulcherrima). Flow-through chambers only enclosing the pot of the plants were considered best for denitrification measurement. Loss of N₂O from the chambers by transport through the plant shoot was negligible with both species. To determine (N₂O + N₂)-N loss, C₂H₂ was applied to inhibit reduction of N₂O. Experiments were conducted with unplanted substrate in closed incubation systems to determine optimum C₂H₂ concentration and pre-treatment duration. Complete inhibition of N₂O reduction in peat substrate was achieved using 1 vol% C₂H₂. However, a concentration of 5 vol% C₂H₂ was chosen for further experiments because C₂H₂ concentrations in flow-through chambers varied. The duration of C₂H₂ pre-treatment (0, 2, 12, 24 h) showed no clear effect on (N₂O + N₂)-N accumulation. However, a pre-treatment duration of 2 h was chosen to guarantee immediate inhibition of N₂O reductase at the start of experiments. Exposure to C₂H₂ gas proved to affect plants of both species. During C₂H₂ exposition in flow-through chambers, the leaves of P. zonale became chlorotic (48 h) and necrotic (72 h). E. pulcherrima showed no chlorosis but did exhibit leaf epinasty (24 h) and wilting (96 h). Transpiration of P. zonale and C availability in the growing medium of both species were not affected by 52 h and 24 h treatments with C₂H₂, respectively. As N emissions usually ended within 38 h of C₂H₂ treatment, it was concluded that side effects of C₂H₂ did not affect denitrification measurements.     

Einfluß von Sorte und Phosphordüngung auf den Phosphorgehalt und die Aktivität der sauren Phosphatasen von Weizen und Gerste. — Ein Beitrag zur Diagnose der P-Versorgung von Pflanzen —

Influence of cultivar and phosphorus application on P concentration and acid phosphatase activity in wheat and barley. — A contribution to the diagnosis of P supply of plants — Acid phosphatase activity compared to total P concentration was studied as a diagnostic criterion of the phosphorus nutritional status of wheat and barley. In a field experiment with wheat cv ‘Sperber’ the influence of P level on P_ase activity and P concentration was monitored at four developmental stages. Significant correlations with grain yield were found for P_ase activity at all four stages whereas P concentration was significantly correlated with grain yield in the early stage (DC 26–27) only. Genetic variability and influence of P supply on P_ase activity and P concentration was studied at low and at high P supply with 9 wheat and 23 barley cultivars grown for 4 and 5 weeks in pot experiments. The variability of P_ase activity caused by cultivars was higher than that caused by P supply. It is, therefore, concluded that the acid phosphatase activity is not suitable as a generally applicable tool for diagnosing P supply. In comparison, total P concentration of the plants was influenced to a higher degree by P supply than by cultivars. Total P is, therefore, more suitable as a criterion for diagnosing P supply of plants than P_ase activity. The samples, though, have to be collected in stages before DC 27.     

Dynamics of Moraxella bovis infection and humoral immune response to bovine herpes virus type 1 during a natural outbreak of infectious bovine keratoconjunctivitis in beef calves

Infectious bovine keratoconjunctivitis (IBK) is an acute disease caused by Moraxella bovis (Mb). Several factors may predispose animals to an IBK outbreak; one commonly observed is infection with bovine herpes virus type 1 (BHV-1). The aim of this study was to investigate the dynamics of BHV-1 virus infection and its relation with clinical cases of IBK in weaned calves from a beef herd with a high prevalence of lesions caused by Mb. Sampling was carried out in six stages and included conjunctival swabs for isolating Mb as well as blood samples for identifying antibodies specific for BHV-1. A score for IBK lesions after observing each eye was determined. The findings of this study showed a high prevalence of BHV-1 virus infection (100% of animals were infected at the end of the trial); 67% of animals were culture-positive for Mb, but low rates of clinical IBK (19% of calves affected) were detected at the end of the trial. These results suggest that infection with BHV-1 did not predispose these animals to IBK, and that Mb infection produced clinical and subclinical disease in the absence of BHV-1 co-infection.     

Manganese in substrate clays—harmful for plants?

Mixtures of peat and substrate clays are commonly used as growth media for horticultural plant production. A quality protocol for substrate clays defines a threshold value of active manganese (Mn_act = sum of exchangeable and easily reducible Mn) in substrate clays of < 500 mg kg^–1 to prevent toxic reactions of plants. This threshold value was tested in experiments with peat‐clay blends under various growth conditions, and nutrient solution experiments were additionally conducted to investigate the effects of silicic acid and dissolved organic matter on the occurrence of Mn toxicity. Common bean (Phaseolus vulgaris L.) and hydrangea (Hydrangea macrophylla) plants were cultivated in different peat‐clay substrates and in peat under different moisture and pH levels. The clays varied in their Mn_act content from 4–2354 mg kg^–1. The results of the substrate experiments reveal that a threshold value for Mn in substrate clays is not justified, as plants grown in all peat‐clay substrates did not develop any Mn toxicity even at high substrate moisture or low pH conditions which are known to increase the Mn availability. The extraction of active Mn did not well reflect the Mn concentrations in plant dry matter and substrate solution. As plants tolerated high Mn concentrations in the substrate solution compared to the nutrient solution without toxicity symptoms, the influence of silicic acid and dissolved organic matter (DOM) on Mn toxicity was characterized in a nutrient‐solution experiment. Manganese toxicity was clearly diminished by silicic acid application, but not by DOM. The former effect probably explains the tolerance of bean plants in peat substrates where high silicon concentrations in the substrate solution were observed. Peat‐clay blends even provided up to five times more silicon to plants than pure peat.     

Bur Raturgefchichte des Flukotters

Ohne Zusammenfassung Unm. v. Red. Jn den meiften Jagdfchriften ift bas Wort Jlukotter als gen. fem. angenommen, in ganz Süddeutfchland aber gilt der im vorliegenden Uuffak beibehaltene Sprachgebrauch, den mir um fo mehr für gerechtfertigt halten, als, mie auch anderw?rts fchon geltend gemacht murde, bie Dtter der Rame einer Schlangenart ift, zudem merden auch, die Wilbfake und das Wiefel ausgenommen, alle übrigen einheimifchen, zum Haarmild geh?rigen Raubthiere als gen. masc. angejprochen.     

Does serum anti‐Müllerian hormone levels always discriminate presence of the ovaries in adult bitches? Comparison of two ELISA kits

Anti‐Müllerian hormone (AMH) is produced in the ovary, and thus, it is an excellent marker of follicle pool in females. Current interest is the clinical use of this parameter as a biomarker to assess presence or absence of an intact ovary and to diagnose ovarian remnant syndrome (ORS) following incomplete ovariohysterectomy (OHE) in bitches. The aim of this study was to evaluate serum AMH concentrations in bitches (n = 34) before and after OHE using two different commercial ELISA kits, one of which is based on detecting human AMH and the other is based on detecting human AMH and the other specified for canine AMH. Furthermore, serum AMH levels were also measured in six ORS cases to compare the diagnostic utility of the two different ELISA kits. Serum AMH concentrations measured using the human and canine kit prior to and after OHE were 0.32 ± 0.24, 0.006 ± 0.22 ng/ml (p < .001) and 12.08 ± 22.81, 9.55 ± 15.42 ng/ml (p = .868), respectively. Thus, the canine‐based kit was not able to reveal the significant drop in serum AMH levels. In conclusion, the human‐based ELISA kits successfully detected the drop in serum AMH concentrations. Reliable results can only be achieved from well‐designed ELISA kits, and AMH levels might be a useful diagnostic tool for the evaluation of presence or absence of ovaries as well as for the detection of ORS cases in bitches.