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Identification and genetic characterisation of xanthomonas campestris pv. Campestris as an oilseed rape pathogen in serbia
No full textDuring 2010, black rot symptoms were observed in oilseed rape plants grown in a commercial plot in Serbia. Ten bacterial isolates obtained from diseased plants, and identified as Xanthomonas campestris pv. campestris (Xcc) based on pathogenicity, physiological and biochemical tests, PTA-ELISA and 16S rDNA sequences analysis, were investigated in detail. Strains were characterized by comparing them by rep-PCR fingerprints using ERIC and (GTG)(5) primers. The 16S rDNA sequences of strains TUr1 and TUr6 were deposited in GenBank under accession Nos. KF057196 and KF057197, respectively. Phylogenetic analysis of the 16S regions showed high similarity level for oilseed rape representative strains and Xcc strains of different origin isolated from kale, cabbage and broccoli
Plum sectorial resistance to Plum pox virus is graft transmissible
No full textGraft transmissibility of the plum sectorial resistance to Plum pox virus (PPV) was investigated. Sectorial resistance is the resistance which is manifested in a sector or portion of infected plant, where virus is not present. Sectorial resistance to PPV is exhibited in the crown or in primary shoots of the plum tree. Double budding method was applied. One bud was carrying sectorial resistance to PPV, while the other one was infected with the virus. Infection on shoots was evaluated by symptoms appearance and serological test for PPV presence.Among three plum cultivars the best results were obtained with cv. "Crvena ranka". Sectorial resistance to PPV has been successfully transmitted by buds of "Crvena ranka". Plum cv. "Č ačanska rodna" failed to transmit sectorial resistance. Plum cv. "Stanley" was between those two above-mentioned plum cultivars
Characterization and evaluation of two Bacillus strains, SS-12.6 and SS-13.1, as potential agents for the control of phytopathogenic bacteria and fungi
No full textTwo strains of Bacillus sp., SS-12.6 and SS-13.1, showed very strong antibacterial and antifungal activity against phytopathogens. The PCR analysis showed that both strains have the genes for biosynthesis of iturin, bacillomycin and surfactin. Kinetics of production of antimicrobial substances in these strains showed that synthesis started at the beginning of exponential phase of growth. Maximum of activity was slowly reached at the beginning of stationary growth phase and was maintained until the end of observed period. Ethyl acetate extracts of cell-free supernatants of both strains were particularly active against several postharvest fungal pathogens, in vitro and in vivo, in the experiment with apple fruits. Mass spectrometry analysis of ethyl acetate extract of the supernatant of strain SS-12.6 confirmed the presence of antimicrobial lipopeptide surfactin. (c) 2013 Elsevier Inc. All rights reserved
PCR-RFLP-based method for reliable discrimination of cryptic species within Mecinus janthinus species complex (Mecinini, Curculionidae) introduced in North America for biological control of invasive toadflaxes
No full textSeveral populations of the stem-mining weevil Mecinus janthinus Germar species complex (Mecinini, Curculionidae), identified based on morphological characteristics, have been introduced in North America for the biological control of invasive toadflaxes of European origin: Linaria vulgaris Miller and L. dalmatica (L.) Miller (Plantaginaceae). According to the mitochondrial cytochrome oxidase subunit II (COII) gene haplotype divergence of Mecinus janthinus species complex, a total of 20 M. janthinus s.s., 3 M. janthinus s.l. of the 'speciosa' genotype and 29 M. janthiniformis haplotypes have been recorded across their native range in central and southeastern Europe. A polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) diagnostic assay of COII gene using Hpy188III and MnlI enzyme-mix, was developed for fast and cost-effective discrimination of these morphologically very similar cryptic weevil species. It is shown that digestion generates unique 4-fragment restriction profile in M. janthinus s.s., 2-fragment profile in M. janthiniformis and 3-fragment profile in M. janthinus s.l. 'speciosa' group of haplotypes, allowing precise identification of each species or genotype. The proposed method represents a practical tool for fast and accurate identification of the target biocontrol agents and should prevent using inappropriate weevil species in redistribution programs for biological control of invasive toadflax species
First Report of Brenneria nigrifluens as the Causal Agent of Shallow-Bark Canker on Walnut Trees (Juglans regia) in Serbia.
No full textDescription of a new relict eriophyoid mite, Loboquintus subsquamatus n. gen. & n. sp (Eriophyoidea, Phytoptidae, Pentasetacini) based on confocal microscopy, SEM, COI barcoding and novel CLSM anatomy of internal genitalia
No full textA new pentasetacine mite Loboquintus subsquamatus n. gen. & n. sp. was found living under scale-like leaves of 2-3 years old twigs of Cupressus sempervirens in Montenegro. This mite species possesses a number of morphological features (uncommon teardrop-shaped body, traits of prosoma, atypical primitive anatomy of the genital apparatus and morphological traits of immatures) which clearly distinguish it from all other known eriophyoids. Adults of L. subsquamatus have seta vi situated on the anterior margin of a uniquely elongate lingua-like thin frontal lobe, three pits on the posterior prodorsal shield margin, a remarkable tube-like structure in the basal part of gnathosoma, a complicated three-layered epigynium, spermathecae directed antero-laterad, short spermathecal tubes and setae eu suppressed in males and possibly expressed in females. External genitalia of males and females of L. subsquamatus are fundamentally similar. Hypothesized remnants of coxisterna III or IV (forming a postgenital plate) are remarkably distinct in males. Two new morphometrical variables are proposed to supplement the CLSM protocol for description of internal genitalia of eriophyoids proposed by Chetverikov et al. (Zootaxa 3560:41-60, 2012b): (a) the length of ventral projection of the transvers genital apodeme and (b) the length of the posterior (=postspermathecal) part of the longitudinal bridge which in L. subsquamatus is remarkably long, whereas in many other eriophyoids it is reduced
Health testing different genotypes alfalfa seeds
No full textIn this study we investigated the presence of plant pathogenic genera of fungi on seeds of three different cultivars of alfalfa (K-22, NS-Banat and OS-88) with three different lots (locality) of each cultivars. When tested cultivars were identified following genera of fungi: Alternaria spp ., Fusarium spp., Penicillium spp., Mucor spp. and sterile mycelium. The presence of the identified genera of fungi ranged from 0% to 2%. Genus Alternaria spp. lowest average value was in alfalfa cultivars K-22 (0.42%), while the highest average value of a cultivar OS-88 (0.58 %), and also at the same cultivar was noted by the presence of one (1%) at the locality of Osijek I. In all the cultivars of alfalfa, a high coefficient of variation, indicating a high variability within the three cultivars for this trait. The highest average attendance of the genus Fusarium spp. was observed in cultivar OS-88 (0.75%), and in the same cultivar is the largest presence (1.25%) were recorded at the locality of Osijek II. For the studied alfalfa cultivars were examined correlations between parameters of seed quality and the presence of pathogens on seeds of different cultivars of alfalfa and lots. Strong positive correlations were observed between germination energy and total germination (r=0.891***), and between mass of 1000 seeds and the presence of Fusarium spp. (r=0.797**). The results of these tests indicate satisfactory state of health of all cultivars and alfalfa seed lots and in particular in relation to the economically important phytopathogenic fungi of the genus Fusarium spp.U ovom radu je ispitivano prisustvo fitopatogenih rodova gljiva na semenu tri različite sorte lucerke (K-22, NS-Banat i OS-88) sa po tri različite partije (lokaliteta) od svake sorte. Kod ispitivanih sorti identifikovani su sledeći rodovi gljiva: Alternaria spp., Fusarium spp., Penicillium spp., Mucor spp. i sterilna micelija. Prisustvo identifikovanih rodova gljiva kretalo se u rasponu od 0% do 2%. Rod Alternaria spp. najmanju prosečnu vrednost imao je kod sorte lucerke K-22 (0.42%), dok je najveću prosečnu vrednost imao kod sorte OS-88 (0.58%), a takođe kod iste sorte konstatovano je najveće prisustvo od (1%) na lokalitetu Osijek I. Kod svih ispitivanih sorata lucerke utvrđen je visok koeficijent varijacije, što ukazuje na visoku varijabilnost unutar samih sorata za ovo svojstvo. Najveće prosečno prisustvo gljiva roda Fusarium spp. zabeleženo je kod sorte OS-88 (0.75%), a kod iste sorte je najveće prisustvo (1.25%) zabeleženo na lokalitetu Osijek II. Na proučavanim sortama lucerke ispitani su korelacioni odnosi između parametara kvaliteta semena i prisustva patogena na semenu različitih sorata i partija lucerke. Jake pozitivne korelacije zabeležene su između energije klijanja i ukupne klijavosti (r=0,891***), kao i između mase 1000 semena i prisustva gljiva iz roda Fusarium spp. (r=0,797**). Rezultati ovih ispitivanja ukazuju na zadovoljavajuće zdravstveno stanje svih sorata i partija semena lucerke a posebno u odnosu na ekonomski značajne fitopatogene gljive iz roda Fusarium spp
Determination of Conyza canadensis Levels of Sensitivity to Glyphosate Trimesium Sulphosate
No full textChanges in leaf anatomy were examined in two S. African populations of Conyza canadensis of which one was presumed to be resistant (CCPR) and the other susceptible (CCS) to glyphosate. Glyphosate was applied to plants, which were grown from seed collected from these populations, at rates of 1, 2 and 4 kg a.e. ha(-1) of TOUCHDOWN [active substance: glyphosate trimesium salt, 500 g L-1] that are equivalent to 2, 4 and 8 L ha (-1) of the herbicide Touchdown. Leaf samples for the light microscope (LM) analysis were collected 3, 7 and 24 h after treatment (HAT). Changes in chlorophyll and shikimate content of leaf material were also examined. Changes in the palisade and pith tissue of leaves were not detected in the investigated populations at 3 and 7 HAT. However, at 24 HAT the different herbicide doses caused changes in leaf anatomy. These changes (injuries) were detected in the CCS at all tested doses, but in the CCPR population of C. canadensis the injuries were observed at only the two highest rates, 2 and 4 kg a.e. ha(-1). Chlorophyll and shikimate contents indicated significant differences between the treated and untreated plants of susceptible population only. Difference in glyphosate resistance between the CCS and CCPR populations was confirmed with an index of resistance of 1.58. This value of the index of resistance indicates that CCS population is 1.58 times more susceptible to glyphosate compared to CCPR population. (C) 2013 Friends Science Publisher
Geographic structure with no evidence for host-associated lineages in European populations of Lysiphlebus testaceipes, an introduced biological control agent
No full textLysiphlebus testaceipes (Cress.) is an aphidiine parasitoid originally introduced to Europe as a biological control agent of citrus aphids in the Mediterranean. It has rapidly become widespread in coastal areas continuing gradually to expand inland. L. testaceipes exploited a large number of aphids in Europe, including new hosts and significantly changed the relative abundance of the native parasitoids. This behavior may reflect a broad oligophagy of the introduced parasitoid or it may require the evolution of host specialization that results in genetically differentiated subpopulations on different hosts. To address this issue we used the mitochondrial cytochrome oxidase subunit I and seven microsatellite loci to analyze the structure of genetic variation for L. testaceipes samples collected from 12 different aphid hosts across seven European countries, as well as some samples from Benin, Costa Rica, USA, Algeria and Libya for comparison. Only five COI haplotypes with moderate divergence were identified overall. There was no evidence for the association of haplotypes with different aphid hosts in the European samples, but there was geographic structuring in this variation. Haplotype diversity was highest in France, where L. testaceipes was introduced, but only a single haplotype was detected in areas of south-eastern Europe that were invaded subsequently. The analysis of microsatellite variation confirmed the lack of host-associated genetic structure, as well as differentiation between populations from south-western and southeastern Europe. The parasitoid L. testaceipes in Europe is thus an opportunistic oligophagous species with a population structure shaped by the processes of introduction and expansion rather than by host exploitation. (C) 2013 Elsevier Inc. All rights reserved
