First detailed report on Puccinia graminis f. sp. avenae virulence structure and Pg resistance genes effective in Poland

European Journal of Plant Pathology - Occurrence of stem rust, caused by Puccinia graminis f. sp. avenae, on oat fields in Europe may lead to significant yield losses. The last P. graminis...     

Effect of mechanical damage on vigor,physiological parameters,and susceptibility of oat (<Emphasis Type="Italic">Avena sativa)</Emphasis> to <Emphasis Type="Italic">Fusarium culmorum</Emphasis> infection

Vigor and selected physiological parameters (content of phenolic compounds, soluble sugars, chlorophyll a and b, and carotenoids) of eight naked and two husked oat cultivars harvested at 15% moisture content were determined. Oat seeds were threshed using two rotational speeds of the threshing drum: 1.6 m s⁻¹ (LS) and 2.4 m s⁻¹ (HS). They were then inoculated with a medium pathogenicity strain of Fusarium culmorum, strain IPO 348–01. In naked cultivars, the use of HS resulted in more severe mechanical damage; in consequence, seedling vigor decreased by 16%. In naked cultivars chlorophyll a and b and carotenoids content were significantly reduced—by more than 64%—when the HS was used. The inoculation caused over a 100% increase of carbohydrates in roots at LS but only a slight increase at HS. Phenolic compound content was twice as high in roots than in leaves after inoculation for both LS and HS. Area of microdamage and reduction of root fresh weight (f.wt.) are significantly correlated with biochemical parameters. Smaller microdamage area and root f.wt. reduction are connected with higher physiological parameters, which confirms lower seedling susceptibility to pathogen infection.     

In vitro immunomodulatory effect of nisin on porcine leucocytes

Nisin, a lantibiotic bacteriocin, has been used for years as a natural food preservative. In addition to its antimicrobial activity, nisin also shows immunomodulatory properties, and the nisin‐producing Lactococcus lactis strain has been successfully tested as a probiotic in weaned piglets. However, the impact of nisin on porcine immune cells has not yet been explored. The objective of the present study was to examine the in vitro immunomodulatory effect of nisin on porcine peripheral blood leucocytes. The whole heparinized blood samples or freshly isolated peripheral blood mononuclear cells (PBMCs) were incubated with different nisin concentrations (0, 1.56, 3.125, 6.25, 12.5, 25 or 50 µg/ml) for 1, 24, 48 or 72 hr. Escherichia coli bacteria were used to stimulate blood phagocytes, while concanavalin A and lipopolysaccharide from E. coli were used as mitogens. Control cells remained unstimulated. MTT colorimetric assay was used to evaluate PBMCs viability and mitogenic response. Phagocyte activity and T‐cell proliferation were measured by flow cytometry. Flow cytometer was also used for immunophenotyping of T cells. Cytokine levels in the culture media were determined using commercial immunoassay (ELISA) kits. The highest concentration of nisin exhibited proliferative activity (p ? 0.05), stimulated interleukin‐1 beta (IL‐1β) and interleukin‐6 (IL‐6) production (both at p ? 0.001), and increased the percentage of CD4⁺CD8⁺ T cells (p ? 0.001) among unstimulated leucocytes. After cell stimulation, however, the highest nisin concentration showed antiproliferative activity (p ? 0.05), decreased phagocytic functions (p ? 0.05) and inhibited the synthesis of IL‐6 (time‐ and concentration‐dependent effect). As a typical bacterial product, nisin had a stronger impact on innate immune cells, and its effect on T cells was likely a consequence of the modulation of the activity of antigen‐presenting cells. Nisin may be a good candidate as an immunomodulator in pig breeding.     

Pedigree, RAPD and simplified AFLP-based assessment of genetic relationships among Avena sativa L. cultivars

Two molecular marker techniques: RAPD and simplified ^PstIAFLP have been compared in order to decide on, which technique is better suited to genetic characterization of oat (Avena sativa L.) cultivars. It was investigated, if the same pattern of variability is revealed by two approaches and whether the observed molecular variability reflects pedigree-based relationships. Polymorphic RAPD and ^PstIAFLP markers were sufficient to distinguish all analysed cultivars, demonstrating the usefulness of both methods for cultivar identification. Genetic similarity estimates derived from RAPD, simplified ^PstIAFLP and combined RAPD and ^PstIAFLP data were compared with coefficients of parentage (COP). Molecular markers-based mean genetic similarities were considerably greater than mean COP value. Correlation coefficients between COP and genetic similarities calculated from RAPD, ^PstIAFLP and combined molecular data were very low and not significant. A better correlation (0.50) was found between similarity estimates derived from RAPD and ^PstIAFLP markers. Four separate dendrograms were constructed based on pedigree and molecular analyses using a neighbor-joining algorithm (NJ). The dendrograms were compared and found to be topologically different. The results of this study showed, that both molecular techniques can be conveniently used for genetic characterization of oat cultivars, however ^PstIAFLP would be the method of choice due to the higher efficiency and reproducibility. This revised version was published online in August 2006 with corrections to the Cover Date.     

Weed-control effects on different types of cover-crop mulches

Abstract

A field experiment was conducted during the period 2002–2006 at the Experimental Farm in Zawady, located in the mid-eastern part of Poland, to evaluate the effect of date of mulch ploughing down (autumn, spring, left till cabbage harvest) and the plant mulches [phacelia (Phacelia tanacetifolia Benth.), vetch (Vicia sativa L.), serradella (Ornithopus sativus), and oat (Avena sativa L.)] on the weed pressure in red cabbage (Brassica oleracea L. var. capitata L. f. rubra) in the first and onion (Allium cepa L. var. cepa Helm.) in the second year after mulching. The biomass yield of plant mulches, total cabbage and onion yields, and biomass and number of weeds before planting and harvest of cabbage and before sowing and harvest of onion were assessed. Weed infestation was determined by the quantitative-weighting method. The biomass yields of phacelia and oat amounted to 26.6 and 24.8 t·ha^?1, respectively, and were almost 2.5-times higher than biomass yields of serradella and vetch. The average cabbage and onion yields were 45.8 and 41.9 t·ha^?1, respectively. The yields of vegetables following mulches were higher than the yields recorded in the unmulched control. The weed species most often found in the experiment were Viola arvensis Murr., Capsella bursa pastoris, Matricaria indora L., Chenopodium album L., and Stellaria media (L.) Vill. Of the examined dates of mulch ploughing down, the spring-incorporated mulches were most effective in reducing the number of weeds in cabbage whereas the nonincorporated mulches showed such an effect in onion. Nonlegumes (phacelia and oat) used as mulch produced higher fresh biomass yields than did vetch and serradella. Oat and phacelia mulches significantly reduced the fresh biomass and number of weeds before cabbage planting. Additionally, oat mulch reduced the fresh biomass of weeds before cabbage harvest. Also, oat and phacelia mulches reduced the number of weeds before onion harvest.     

Regulation of growth hormone secretion in nursing ewes: an involvement of μ-receptor subtype

Suckling by newborns induces a surge of lactogenic hormones, that is prolactin and growth hormone (GH), in mother's body, with endogenous opioid peptide (EOP) participating in generation of this surge. The aim of the current study was to investigate which types of opioid receptors are involved in generation of the GH surge in ewes during suckling. A series of intracerebroventricular infusions of opioid receptors antagonists: naloxone (for all types of receptors), naloxonazine (specific for μ receptor) and 5'-guanidinonaltrindole (GNTI--specific for κ receptor) and the vehicle (control) were performed in nursing sheep during the fifth week of lactation. All infusions were carried out in a serial manner: five 30-min infusions (60 μg/60 μl) from 10:00 to 15:00, at 30-min intervals. The period of the experiment consisted of the non-suckling (10:00-12:30) and suckling (12:30-15:00) periods. Simultaneously, blood samples were collected at 10-min intervals to determine plasma GH concentration by radioimmunoassay. Suckling evoked a rapid increase in GH concentration in control ewes. Naloxone and naloxonazine significantly decreased both the basal GH release in the non-suckling period and the suckling-induced GH surge. Specifically, the suppressive effect concerned either the duration or the amplitude of the GH surge. In contrast, GNTI did not significantly affect the GH release. In conclusion, the EOPs may affect the regulatory process of GH secretion in lactating sheep, especially through μ opioid receptor.     

Transcriptomic gene profiling of porcine muscle tissue depending on histological properties

In pig, the histological profile of muscle tissue, especially the proportion of individual fiber types, is one of the main factors affecting meat quality properties. In the present research, RNA sequencing (RNA‐seq) by using next generation sequencing method was applied to estimate the whole gene expression profile of Longissimus lumborum muscle of pigs (Large White breed) differing in the percentage of two fiber types (slow‐twitch (type I) fibers and fast‐twitch glycolytic (type IIB) fibers). The RNA‐seq approach allowed us to identify 355 differentially expressed genes (DEGs) indicated as significant (false discovery rate‐adjusted P < 0.05) using three types of software: DESeq2, edgeR and baySeq. Detected genes and pathways deregulated in muscle depending on tissue microstructure were associated with: metabolic processes – 158 genes; cellular processes – 122; biological regulation – 62; localization – 51; and 35 genes with developmental processes. The DEGs were included in: PI3K‐Akt; FoxO and MAPK signaling pathways, regulation of actin cytoskeleton, lysine degradation and insulin signaling pathway as well as mTOR and Hippo signaling pathways. These results highlight the mainly metabolic pathways related to glucose metabolism and contraction processes of muscle cells. Detection of genes involved in variation of fiber‐type distribution will be useful in understanding of the genetic factors affecting muscle structure, metabolic process and indirectly, meat quality traits.     

Physicochemical properties and release characteristics of calcium alginate microspheres loaded with Trichoderma viride spores

Novel agroformulations for simultaneous delivery of chemical and biologically active agents to the plants were prepared by encapsulation of Trichoderma viride spores in calcium alginate microspheres. The impact of calcium ions concentration on the viability and sporulation of T. viride spores as well as on the microsphere important physicochemical properties were investigated. Intermolecular interactions in microspheres are complex including mainly hydrogen bonds and electrostatic interactions. T. viride germination inside matrix and germ tubes penetration out of microspheres revealed calcium alginate microspheres provide a supportive environment for T. viride growth. Differences in physicochemical properties and bioactive agents release behaviour from microspheres were ascribed to the changes in microsphere structure. Fitting to Korsmeyer-Peppas empirical model revealed the underlying T. viride release mechanism as anomalous transport kinetics (a combination of two diffusion mechanisms and the Type II transport (polymer swelling and relaxation of the polymeric matrix)). The increasing amount of T. viride spores in the surrounding medium is closely related to the release from microspheres and germination. The rate controlling mechanism of calcium release is Fickian diffusion. A decrease in the release rate with increasing calcium ion concentrations is in accordance with the calcium ions effect on the strength of the alginate network structure. T. viride germination inside microsphere diminished the amount of released calcium ions and slowed release kinetics in comparison with microspheres prepared without T. viride. The results indicated investigated agroformulations have a great potential to be used for plant protection and nutrition.     

The use of bromelain as a feed additive in fish diets: Growth performance,intestinal morphology,digestive enzyme and immune response of juvenile Sterlet (Acipenser ruthenus)

Bromelain is a proteolytic enzyme extracted from Ananas comosus and has great potential to affect several physiological functions. The current study examined the effect of bromelain added to commercial feed at concentrations of 0 g (control), 10 g (B1) and 20 g (B2) per kg diet on growth, feed utilization, intestinal morphology, digestive enzyme and immune response of juvenile Sterlet (Acipenser ruthenus) for 56 days. At the end of this experiment, the highest final body weight was detected in fish fed diet of B2 compared to control. The protein content of whole fish was higher in fish fed diet of B1 and B2, but the content of calcium, iron, copper and zinc was noted lower in fillets of fish fed diet of B1 and B2. Supplementation with bromelain significantly increased the height of mucosal folds, enterocytes and the supranuclear zone of the epithelial cells compared to control diet. The enzymatic activity of lipase and pepsin was significantly (p < 0.05) higher in fish fed diet of B1 and B2. The highest activity of lysozyme, total protein level and total immunoglobulin and the proliferative activity of T and B cells were detected in fish fed diet of B2 compared to control, where no significant (p > 0.05) difference was found in ceruloplasmin, metabolic activity of spleen macrophages and potential killing activity of spleen phagocytes between different treatments.