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Iskalni niz: "avtor" (Nataša Mehle) .

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Epidemiology of flavescence dorée and hazelnut decline in Slovenia : geographical distribution and genetic diversity of the associated 16SrV phytoplasmas
Zala Kogej Zwitter, Gabrijel Seljak, Tjaša Jakomin, Jakob Brodarič, Ana Vučurović, Sandra Pedemay, Pascal Salar, Sylvie Malembic-Maher, Xavier Foissac, Nataša Mehle, 2023, izvirni znanstveni članek

Povzetek: Flavescence dorée (FD) phytoplasma from 16SrV-C and -D subgroups cause severe damage to grapevines throughout Europe. This phytoplasma is transmitted from grapevine to grapevine by the sap-sucking leafhopper Scaphoideus titanus. European black alder and clematis serve as perennial plant reservoirs for 16SrV-C phytoplasma strains, and their host range has recently been extended to hazelnuts. In Slovenia, hazelnut orchards are declining due to 16SrV phytoplasma infections, where large populations of the non-autochthonous leafhopper Orientus ishidae have been observed. To better characterise the phytoplasma-induced decline of hazelnut and possible transmission fluxes between these orchards and grapevine, genetic diversity of 16SrV phytoplasmas in grapevine, hazelnut and leafhoppers was monitored from 2017 to 2022. The nucleotide sequence analysis was based on the map gene. The most prevalent map genotype in grapevine in all wine-growing regions of Slovenia was M54, which accounted for 84 % of the 176 grapevines tested. Besides M54, other epidemic genotypes with lower frequency were M38 (6 %), M51 (3 %), M50 (2 %) and M122 (1 %). M38, M50 and M122 were also detected in infected cultivated hazelnuts and in specimens of O. ishidae leafhopper caught in declining hazelnut orchards. It suggests that this polyphagous vector could be responsible for phytoplasma infection in hazelnut orchards and possibly for some phytoplasma exchanges between hazelnuts and grapevine. We hereby describe new genotypes: M158 in grapevine as well as four never reported genotypes M159 to M162 in hazelnut. Of these four genotypes in hazelnut, one (M160) was also detected in O. ishidae. Analysis of additional genes of the new genotypes allowed us to assign them to the VmpA-III cluster, which corresponds to the 16SrV-C strains previously shown to be compatible with S. titanus transmission.
Ključne besede: phytoplasmas, haselnuts, grapevine, Flavescence dorée, epidemiology, plant disease
Objavljeno v DiRROS: 26.07.2023; Ogledov: 103; Prenosov: 39
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In-depth study of tomato and weed viromes reveals undiscovered plant virus diversity in an agroecosystem
Mark Paul Selda Rivarez, Anja Pecman, Katarina Bačnik, Olivera Maksimović, Ana Vučurović, Gabrijel Seljak, Nataša Mehle, Ion Gutiérrez-Aguirre, Maja Ravnikar, Denis Kutnjak, 2023, izvirni znanstveni članek

Povzetek: Background: In agroecosystems, viruses are well known to influence crop health and some cause phytosanitary and economic problems, but their diversity in non-crop plants and role outside the disease perspective is less known. Extensive virome explorations that include both crop and diverse weed plants are therefore needed to better understand roles of viruses in agroecosystems. Such unbiased exploration is available through viromics, which could generate biological and ecological insights from immense high-throughput sequencing (HTS) data. Results: Here, we implemented HTS-based viromics to explore viral diversity in tomatoes and weeds in farming areas at a nation-wide scale. We detected 125 viruses, including 79 novel species, wherein 65 were found exclusively in weeds. This spanned 21 higher-level plant virus taxa dominated by Potyviridae, Rhabdoviridae, and Tombusviridae, and four non-plant virus families. We detected viruses of non-plant hosts and viroid-like sequences and demonstrated infectivity of a novel tobamovirus in plants of Solanaceae family. Diversities of predominant tomato viruses were variable, in some cases, comparable to that of global isolates of the same species. We phylogenetically classified novel viruses and showed links between a subgroup of phylogenetically related rhabdoviruses to their taxonomically related host plants. Ten classified viruses detected in tomatoes were also detected in weeds, which might indicate possible role of weeds as their reservoirs and that these viruses could be exchanged between the two compartments. Conclusions: We showed that even in relatively well studied agroecosystems, such as tomato farms, a large part of very diverse plant viromes can still be unknown and is mostly present in understudied non-crop plants. The overlapping presence of viruses in tomatoes and weeds implicate possible presence of virus reservoir and possible exchange between the weed and crop compartments, which may influence weed management decisions. The observed variability and widespread presence of predominant tomato viruses and the infectivity of a novel tobamovirus in solanaceous plants, provided foundation for further investigation of virus disease dynamics and their effect on tomato health. The extensive insights we generated from such in-depth agroecosystem virome exploration will be valuable in anticipating possible emergences of plant virus diseases and would serve as baseline for further post-discovery characterization studies.
Ključne besede: tomato, weed, virus, viroid, virome, virus discovery, virus diversity, phylogenetics, metagenomics, viromics
Objavljeno v DiRROS: 13.04.2023; Ogledov: 237; Prenosov: 50
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Geographical and temporal diversity of ‘Candidatus Phytoplasma solani' in wine-growing regions in Slovenia and Austria
Nataša Mehle, Sanda Kavčič, Sara Mermal, Sara Vidmar, Maruša Pompe Novak, Monika Riedle-Bauer, Günter Brader, Aleš Kladnik, Marina Dermastia, 2022, izvirni znanstveni članek

Povzetek: As the causal agent of the grapevine yellows disease Bois noir, ‘Candidatus Phytoplasma solani’ has a major economic impact on grapevines. To improve the control of Bois noir, it is critical to understand the very complex epidemiological cycles that involve the multiple “Ca. P. solani” host plants and insect vectors, of which Hyalesthes obsoletus is the most important. In the present study, multiple genotyping of the tuf, secY, stamp, and vmp1 genes was performed. This involved archived grapevine samples that were collected during an official survey of grapevine yellows throughout the wine-growing regions of Slovenia (from 2003 to 2016), plus samples from Austrian grapevines, stinging nettle, field bindweed, and insect samples (collected from 2012 to 2019). The data show that the tuf-b2 type of the tuf gene has been present in eastern Slovenia since at least 2003. The hypotheses that the occurrence of the haplotypes varies due to the geographical position of Slovenia on the Italian–Slovenian Karst divide and that the haplotypes are similar between Slovenian and Austrian Styria were confirmed. The data also show haplotype changes for host plants and H. obsoletus associated with ‘Ca. P. solani,’ which might be linked to new epidemiological cycles of this phytoplasma that involve not just new plant sources and new insect vectors, but also climate and land-use changes.
Ključne besede: Bois noir, genotyping, ‘Ca. P. solani’, tuf gene, secY, survey, tuf-b2, stamp
Objavljeno v DiRROS: 10.06.2022; Ogledov: 539; Prenosov: 321
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