Nepovirusai Lietuvoje, jų sukeliamos augalų ligos ir virusų izoliatų genetinė įvairovė

Currently there are 21 families and 92 genera of plant viruses (Fauquet, Mayo, 2012). Nepovirus is quite unique genus with characteristics that distinguish it from all other plant viruses. Members of this genus are spread in a semi persistent maner by parasitic soil nematodes belonging to Longidorus or Xiphinema genera. This gave birth to genus name – nematode transmitted, polyhedral viruses. Although nematodes cannot carry virus long distances, they remain in soil during winter and can infect new plants in spring. This allows the virus to circulate and remain in soil for indefinite time. Many nepoviruses can also spread by seeds and pollen. Seeds allow only vertical transmission of virus, but it is the only way for nepoviruses to spread long distances. With seed export viruses can be introduced to new continents and ecological niches

Nepovirus caused plant diseases and genetic variability of virus isolates in Lithuania

Currently there are 21 families and 92 genera of plant viruses (Fauquet, Mayo, 2012). Nepovirus is quite unique genus with characteristics that distinguish it from all other plant viruses. Members of this genus are spread in a semi persistent maner by parasitic soil nematodes belonging to Longidorus or Xiphinema genera. This gave birth to genus name – nematode transmitted, polyhedral viruses. Although nematodes cannot carry virus long distances, they remain in soil during winter and can infect new plants in spring. This allows the virus to circulate and remain in soil for indefinite time. Many nepoviruses can also spread by seeds and pollen. Seeds allow only vertical transmission of virus, but it is the only way for nepoviruses to spread long distances. With seed export viruses can be introduced to new continents and ecological niches

A novel RFLP method for identification of morphologically similar avian Sarcocystis species

Protozoans of genus Sarcocystis are widespread parasites infecting mammals, birds, and reptiles. Morphology of their sarcocysts is an important criterion for species identification. However, as more and more morphologically similar Sarcocystis species are being found and described, additional methods for their routine diagnostics are needed. We investigated restriction fragment length polymorphism (RFLP) as potential alternative to sequencing data analysis for the identification of Sarcocystis species using birds as an intermediate host. The internal transcribed spacer 1 (ITS1) region sequences of seventeen Sarcocystis species (S. albifronsi, S. anasi, S. calchasi, S. columbae, S. cornixi, S. corvusi, S. cristata, S. halieti, S. falcatula, S. fulicae, S. kutkienae, S. lari, S. lindsayi, S. rileyi, S. turdusi, S.wenzeli, and S. wobeseri) of interest were analysed and five best-fitting endonucleases generating most informative restriction fragments were selected for routine testing. In general, RFLP analyses are always inconclusive as they target very short DNA sequences. However, it can be an irreplaceable technique when fast and cheap identification and discrimination of known species are required, which was our main goal and preliminary results indicate that RFLP could be successfully used when identifying closely related avian Sarcocystis species with just two nucleases

Pseudomonas syringae patogeninės bakterijos Lietuvoje auginamuose javuose

Pseudomonas syringae pathovars cause bacterial diseases of cereals in nearly all temperate and subtropical cerealgrowing regions. As being of low importance compared to fungal diseases, P. syringae has not been studied in cereal crops in Lithuania. However, leaf blights and glume discolorations, uncharacteristic of fungal diseases, were found relatively frequently in the fields. Therefore, the study aimed to identify the occurrence of P. syringae in cereals grown in Lithuania. In this study, cereal crops were tested for the presence of plant pathogen P. syringae. In total, 452 symptomatic plant samples of winter wheat, winter triticale, spring wheat and spring barley were collected in 2013–2015. Symptoms of leaf blight and basal glume blotch on grain were more frequently detected in spring and winter wheat crops than in winter triticale and spring barley. Symptomatic leaves and grain yielded 113 P. syringae strains (51 from leaves and 62 from grain), but only 13 strains (10 from wheat, 2 from triticale and 1 from barley) were pathogenic to host plants when tested by spray method (SM). These strains were isolated from grain (10 strains) and leaves (3 strains) of all sampled plant species originating from different districts of the country. Based on 16S rRNA gene sequence analysis, leaf injection method (LIM) and origin of pathogenic strain, it can be assumed that P. syringae pv. atrofaciens is the dominat causal agent of bacterial diseases of cereals, particularly basal glume blotch of wheat

secA gene suitability for fast and easy identification of Phytoplasmas by RFLP analysis

n this study we investigated the secA gene as possible marker to supplement the classification scheme based on 16S rRNA sequences. We cloned and sequenced secA gene and its flanking region of 'Ca. P. asteris' CPh strain phytoplasma, as well as 1997 bp length secA gene fragment of Canada peach X-disease CX and 1327 bp fragment of 'Ca. P. ziziphi' JWB. This helped us to select a primer pair for a single step PCR that can amplify similar to 1200 kb length fragment of secA gene from different phytoplasma groups. We propose that this fragment could be used in RFLP analysis to quickly identify and distinguish 16SrI-A, I-B, I-C, I-D, III-A, III-B, III-E, III-F, III-H, V-B, XII-B and XXI-A subgroup phytoplasmas using just two restriction endonucleases

16SrI-a pogrupio fitoplazmų sukelta epidemija sode Vilniaus rajone Lietuvoje

Here we report on a plant disease caused by insect-transmitted unculturable plant pathogenic bacteria detected in a private garden in Vilnius region. Samples of symptomatic peas (Pisum sativum L.), nasturtium (Tropaeolum majus L.), strawberry (Fragaria × ananassa Duchesne) and zucchini (Cucurbita pepo var. giromontina) plant tissues were collected. Based on the molecular technique, the Internet tools and phylogenetic analysis, these pathogens were identified as phytoplasmas and classified in phytoplasma RFLP (restriction fragment length polymorphism) group 16SrI, subgroup A. Because this pathogen may be spread by insect-vector that comes from the wild nature, the phytoplasmas could cause a problem in agriculture of Lithuania

Protozoan parasites of Sarcocystis spp. in rodents from commercial orchards

Simple Summary Small mammals not only play an important role in ecosystems, but they also can transmit a wide range of pathogens to humans and domestic animals. The data on protozoan Sarcocystis parasites in orchard-dwelling small mammals are still scarce. Members of the genus Sarcocystis form sarcocysts in the muscles of intermediate hosts and develop sporocysts in the intestines of definitive hosts. In the present study, 679 muscle samples of small mammals, collected in commercial orchards and berry plantations in Lithuania, were screened for Sarcocystis parasites via DNA analysis. The prevalence of Sarcocystis spp. was low as only nine pooled muscle samples were found to contain the parasites examined. Four species were identified in the examined small mammals, including two potentially new Sarcocystis species that were detected in the muscles of voles. The phylogenetic results suggested that birds and mammals are the definitive hosts of the Sarcocystis spp. identified in the current study. Small mammals are an important group of wildlife that can transmit pathogens to humans and animals. There is a lack of comprehensive studies on the protozoan parasites of the genus Sarcocystis in agricultural areas. The aim of the current research was to evaluate the prevalence of Sarcocystis spp., and to identify the parasite species found in the skeletal muscles of rodents and insectivores from commercial orchards. A total of 679 muscle samples from small mammals, mainly rodents (n = 674), belonging to eight species were examined. Muscle samples were pooled into groups, then digested, and the presence of the Sarcocystis species was confirmed by molecular methods. The examined parasites were determined in five rodent species, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Microtus arvalis, and M. oeconomus. The prevalence of Sarcocystis spp. was low: 2.23% in voles and 0.79% in mice. Based on a sequence comparison of cox1 and 28S rDNA, four species were identified: S. myodes, Sarcocystis cf. strixi, Sarcocystis sp. Rod1, and Sarcocystis sp. Rod2. This is the first report of S. myodes in A. agrarius, A. flavicollis, and M. arvalis. The identified species were most closely related to Sarcocystis spp., and were transmitted by predatory mammals and birds. Future studies are needed to describe the species morphologically, as well as to define the host spectrum and to evaluate their possible pathogenicity

Soil Fungistasis against <i>Fusarium Graminearum</i> under Different tillage Systems

The establishment of the harmful pathogen Fusarium graminearum in different agroecosystems may strongly depend on the ability of the soils to suppress its development and survival. This study aimed to evaluate the influence of different soil tillage systems (i.e., conventional tillage, reduced tillage and no-tillage) on soil fungistasis against F. graminearum. Soil samples were collected three times during the plant growing season in 2016 and 2017 from a long-term, 20-year soil tillage experiment. The F. graminearum in the soil samples was quantified by real-time qPCR. The soil fungistasis was evaluated by the reduction in the radial growth of F. graminearum in an in vitro assay. The antagonistic activity of the soil bacteria was tested using the dual culture method. The F. graminearum DNA contents in the soils were negatively correlated with soil fungistasis (r = –0.649 *). F. graminearum growth on the unfumigated soil was reduced by 70–87% compared to the chloroform fumigated soil. After the plant vegetation renewal, the soil fungistasis intensity was higher in the conventionally tilled fields than in the no-tillage. However, no significant differences were obtained among the tillage treatments at the mid-plant growth stage and after harvesting. 23 out of 104 bacteria isolated from the soil had a moderate effect, and only 1 had a strong inhibitory effect on the growth of F. graminearum. This bacterium was assigned 100% similarity to the Bacillus amyloliquefaciens Hy7 strain (gene bank no: JN382250) according to the sequence of the 16S ribosome subunit coding gene. The results of our study suggest that the presence of F. graminearum in soil is suppressed by soil fungistasis; however, the role of tillage is influenced by other factors, such as soil biological activity, type and quantity of plant residues and environmental conditions