Distribution of PPV-D and PPV-Rec strains of Plum pox virus in Serbia and the dynamics of their spread in plum orchard

Virus šarke šljive (Plum pox virus-PPV), prouzrokovač bolesti šarke šljive, je prisutan u Srbiji skoro 80 godina i smatra se ekonomski najznačajnijim virusom koštičavih voćaka. Od 7 opisanih sojeva PPV, u Srbiji je potvrđeno prisustvo tri soja: PPV-M, PPV-D i PPV-Rec. U cilju utvrđivanja raširenosti sojeva šarke u zasadima šljive i kajsije u Srbiji, u periodu 2008‒2010. godine, standardizovanom procedurom je sakupljeno ukupno 283 uzoraka lišća šljive i kajsije iz preko 90 zasada. Tipiziranje detektovanih izolata sprovedeno je IC-RT-PCR metodom kroz 4 odvojene PCR reakcije sa PPV-M i PPV-D specifičnim prajmerima sa ciljnim sekvencama u dva regiona genoma. Za filogenetsku analizu i utvrđivanje stope diverziteta odabran je 41 izolat za sekvencioniranje fragmenata iz dva regiona genoma (C-ter NIb‒N-ter CP i C-ter P3‒6K1‒N-ter CI). U cilju ispitivanja dinamike širenja PPV-D i PPV-Rec sojeva u direktnoj kompeticiji, tokom 2008. godine podignut je eksperimentalni zasad sa 400 stabala šljive sorte Čačanska lepotica. Osam stabala, koja su locirana u sredini zasada, su inokulisana sa potpuno okarakterisanim PPV-D i PPV-Rec izolatima (4 stabla po izolatu-interni izvor infekcije). Sva stabla Prunus vrsta u neposrednoj okolini zasada su markirana, uzorkovana i testirana na prisustvo PPV (eksterni izvor infekcije). Pozitivni uzorci su sekvencionirani u C-ter NIb‒N-ter CP regionu genoma za dalju uporednu analizu sa sekvencama inokulisanih i novoinficiranih stabala u zasadu. Svake godine, od 2008‒2011., sva stabla u eksperimentalnom zasadu su vizuelno pregledana i ispitivana ELISA testom na prisustvo PPV. Pozitivni uzorci su tipizirani IC-RT-PCR metodom i sekvencionirani u C-ter NIb‒Nter CP regionu genoma. Tokom poslednje tri godine istraživanja vršeno je praćenje prisustva i dinamike brojnosti lisnih vaši u eksperimentalnom zasadu...Plum pox virus (PPV), the agent of Sharka disease, is present in Serbia almost 80 years and it is considered as economically the most important virus of stone fruits. Three strains, out of 7 described, are present in Serbia: PPV-M, PPV-D and PPV-Rec. In order to determine the prevalence of strains in plum and apricot orchards in Serbia during the three-year period (2008-2010), a total of 283 plum and apricot leaf samples from over 90 orchards were collected by standardized procedure. Strain-typing of isolates was done by IC-RT-PCR in 4 separate PCR reactions with PPV-M and PPV-D specific primers with target sequences in two different genomic regions. For phylogenetic analysis and determination of diversity rate, 41 isolates were selected for sequencing fragments from two genomic regions (C-ter NIb‒N-ter CP and C-ter P3‒6K1‒N-ter CI). In order to study the dynamics of spread of PPV-D and PPV-Rec strains in direct competition, an experimental plum orchard of 400 trees of Čačanska lepotica variety was built in 2008. Eight trees, which are located in the middle of the orchard, were inoculated with a fully characterized PPV-D and PPV-Rec isolates (4 trees per isolate-internal source of infection). All Prunus trees in the vicinity of the experimental orchard were marked, sampled and tested for the presence of PPV (external source of infection). Positive samples were sequenced in C-ter NIb‒N-ter CP genomic region for further analysis with sequences of inoculated and newly infected trees in the orchard. Every year, from 2008‒2011, all trees from the orchard were visually inspected and tested by ELISA for the presence of PPV. ELISA positive samples were typed by IC-RT-PCR and sequenced in the C-ter NIb‒N-ter CP genomic region. During the last three years of research, the presence and the number of aphids in the experimental orchard were monitored..

Walsh analysis - a convenient preprocessor for period detection in astronomy

Walsh analysis is practically analogous to Fourier analysis, except that square wave is used instead of the sine one. It has one major advantage over Fourier - it can be performed much faster. This may seem of little importance at first, since computers have gotten to the point where most programmers do not take any care about the size of their code or the speed of their calculations. However, LSST will provide astronomers with huge data sets, and searching for periodicity peaks with high resolution might require enourmous amount of calculations. To perform this analysis in real time (a matter of seconds) it is important to skip non-necessary mathematical operations and focus on applying complex period detection algorithms (such as line fitting, analysis of variance, and others) only in the vicinity of expected peaks, not on all arbitrary periods. To do this efficiently, we propose that Walsh analysis is applied on the data first. A simulation was conducted with artifiucially generated light curves for the three types of variable stars: RRLyr, Algols and classical cepheids. LSST current baseline cadence (enigma 1189) was used for the timing of samples

The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models

The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high-quality, homogeneous photometry of 65 globular clusters. This paper introduces a new collection of stellar evolution tracks and isochrones suitable for analyzing the ACS survey data. Stellar evolution models were computed at [Fe/H] = -2.5, -2.0, -1.5, -1.0, -0.5, and 0; [α/Fe] = -0.2, 0, 0.2, 0.4, 0.6, and 0.8; and three initial He abundances for masses from 0.1 to 1.8 M⊙ and ages from 2 to 15 Gyr. Each isochrone spans a wide range in luminosity, from MV ~ 14 up to the tip of the red giant branch. These are complemented by a set of He-burning tracks that extend from the zero-age horizontal branch to the onset of thermal pulsations on the asymptotic giant branch. In addition, a set of computer programs are provided that make it possible to interpolate the isochrones in [Fe/H], generate luminosity functions from the isochrones, and create synthetic horizontal-branch models. The tracks and isochrones have been converted to the observational plane with two different color-Teff transformations, one synthetic and one semiempirical, in ground-based B, V, and I, and F606W and F814W for both ACS WFC and WFPC2 systems. All models and programs presented in this paper are available at the Dartmouth Stellar Evolution Database and the Multimission Archive at the Space Telescope Science Institute

The Dartmouth Stellar Evolution Database

The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from –2.5 to +0.5, [α/Fe] from –0.2 to +0.8 (for [Fe/H] ≤ 0) or +0.2 (for [Fe/H] \u3e 0), and initial He mass fractions from Y = 0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 M☉, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)C, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS/WFC and WFPC2

THE EFFECTS OF SOLAR ACTIVITY: ELECTRONS IN THE TERRESTRIAL LOWER IONOSPHERE

Solar flare X-ray energy can cause strong enhancements of the electron density in the Earth’s atmosphere. This intense solar radiation and activity can cause sudden ionospheric disturbances (SIDs) and further create ground telecommunication interferences, blackouts as well as some natural disasters and caused considerable material damage. The focus of this contribution is on the study of these changes induced by solar X-ray flares using narrowband Very Low Frequency (VLF, 3–30 kHz) and Low Frequency (LF, 30–300 kHz) radio signal analysis. The model computation and simulation were applied to acquire the electron density enhancement induced by intense solar radiation. The obtained results confirmed the successful use of applied technique for detecting space weather phenomena such as solar explosive events as well for describing and modeling the ionospheric electron density which are important as the part of electric terrestrial-conductor environment through which external-solar wind (SW) electrons can pass and cause natural disasters on the ground like fires

Stellar Population Models and Individual Element Abundances I: Sensitivity of Stellar Evolution Models

Integrated light from distant galaxies is often compared to stellar population models via the equivalent widths of spectral features--spectral indices--whose strengths rely on the abundances of one or more elements. Such comparisons hinge not only on the overall metal abundance but also on relative abundances. Studies have examined the influence of individual elements on synthetic spectra but little has been done to address similar issues in the stellar evolution models that underlie most stellar population models. Stellar evolution models will primarily be influenced by changes in opacities. In order to explore this issue in detail, twelve sets of stellar evolution tracks and isochrones have been created at constant heavy element mass fraction Z that self-consistently account for varying heavy element mixtures. These sets include scaled-solar, alpha-enhanced, and individual cases where the elements C, N, O, Ne, Mg, Si, S, Ca, Ti, and Fe have been enhanced above their scaled-solar values. The variations that arise between scaled-solar and the other cases are examined with respect to the H-R diagram and main sequence lifetimes.Comment: 33 pages, 13 figures, accepted to Ap

Morphological description and molecular detection of Pestalotiopsis sp on hazelnut in Serbia

In autumn 2015, hazelnut plants with leaf blight symptoms were noticed in a commercial plantation in the Province of Vojvodina, Serbia. Symptomatic samples were collected and submitted to laboratory analysis. Based on morphological characterization, the fungus isolated from the material was initially identified as Pestalotiopsis sp. Pathogenicity tests showed that two selected isolates infected hazelnut leaves and fruits that developed symptoms after artificial inoculation. The pathogen was re-isolated from diseased leaves and fruits, confirming Koch's postulates. Molecular identification was performed with sequence and phylogenetic analysis of ITS, EF1-alpha, and TUB genomic regions. Phylogenetic analysis confirmed the results of the morphological identification. The detection of Pestalotiopsis sp., a causal agent of leaf blight on hazelnut in Serbia, is one of a few reports of these pathogenic fungi on hazelnut

Comparative study of different surface sterilization treatments and optimal month for establishment of aseptic cultures of raspberry cultivars

Removing contaminants from plant material with minimal damage to plant cells using different chemical solutions represents very important and one of the most critical steps in establishing plant tissue culture in vitro. Our study deals with the optimisation of the protocol for successful surface sterilization of initial explants in two raspberry cultivars, ‘Meeker’ and ‘Willamette’ in two experimental years. The main objective during the first experimental year was to examine the protocols for surface sterilization which included different combinations of disinfectants (mercuric chloride or commercial bleach solution each in combination with 70% ethanol). In the following year, the impact of the two most effective sterilization treatments on the establishment of aseptic cultures over the four-month period (May, June, July, and August) was investigated in both raspberry cultivars. Aseptic cultures were established on Murashige and Skoog medium (MS) containing 2.0 mg/l N6-Benzyladenine (BA), 0.5 mg/l indole-3-butyric acid (IBA) and 0.1 mg/l gibberellic acid (GA3). The highest percentage of explants initiation in ‘Meekerʼ (79.3%) was achieved with surface sterilization in 70% ethanol (1 min) combined with 10% (v/v) commercial bleach solution (20 min), whereas sterilization in 70% ethanol (1 min) followed by HgCl2 (3 min) gave the best results (38.3%) in ‘Willametteʼ. The most optimal month for the establishment of aseptic culture was May for ‘Meeker’, while June was the most suitable month for the ‘Willametteʼ cultivar

Aktuelna istraživanja u oblasti zaštite voćaka

The study results of new economically important causal agents of diseases and fruit pests were presented. Over 20 types of Erwinia amylovora have been isolated and identified on pome fruits. The most frequent peach, apricot, and plum diseases are the following: brown fruit rot, drying of small branches and canker. The importance of virus free planting material and resistant cultivars was emphasized. Using the nested PCR and PCR-RFLP methods showed the presence of Phytophthora fragarie var. rubi on three raspberry cultivars. Cecidial raspberry drying is one of the most economically harmful disease. Bacterial raspberry blight was described for the first time in Serbia. Acarology studies are directed towards the following: mechanisms of plant resistance, resistance of mites towards acaricides, efficacy of biopesticides and development of molecular methods for the faster identification of species. The increase in the population of Lymatria dispar, Cacopsylla pruni and Carcopidae was assessed in orchards.Prikazani su rezultati istraživanja novih bolesti i štetočina voćaka sa posebnim osvrtom na: molekularnu detekciju patogena, Pseudomonas syringae na koštičavom voću, sojeve Erwinia amylovora na jabučastim voćkama, prouzrokovače mrke truleži (Monilinia spp.) i rak rana (Leucostoma spp.) na koštičavim vrstama voćaka, molekularne metode za utvrđivanje prisustva Phytophthora fragariae var. rubi na malini, cecidoizno sušenje maline, prouzrokovača bakteriozne plamenjače maline (Pseudomonas syringae pv. syringae), akarološka istraživanja, kao i na porast brojnosti Lymantria dispar, Cacopsylla pruni i cikada penuša (Cercopidae), zaštitu voćaka u organskoj proizvodnji

Rosetta mission: Electron scattering cross sections-data needs and coverage in BEAMDB database

The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is handicapped by a lack of detailed knowledge of electron impact cross sections which highlights the need for a broad range of electron scattering data from the molecular systems detected on the comet. In this paper, we present an overview of the needs for electron scattering data relevant for the understanding of observations in coma, the tenuous atmosphere and on the surface of 67P/Churyumov-Gerasimenko during the Rosetta mission. The relevant observations for elucidating the role of electrons come from optical spectra, particle analysis using the ion and electron sensors and mass spectrometry measurements. To model these processes electron impact data should be collated and reviewed in an electron scattering database and an example is given in the BEAMD, which is a part of a larger consortium of Virtual Atomic and Molecular Data Centre-VAMDC