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1391.
Genomic characterisation of the new Dickeya fangzhongdai species regrouping plant pathogens and environmental isolates
Špela Alič, Jacques Pédron, Tanja Dreo, Frédérique van Gijsegem, 2019, original scientific article

Abstract: Background The Dickeya genus is part of the Pectobacteriaceae family that is included in the newly described enterobacterales order. It comprises a group of aggressive soft rot pathogens with wide geographic distribution and host range. Among them, the new Dickeya fangzhongdai species groups causative agents of maceration-associated diseases that impact a wide variety of crops and ornamentals. It affects mainly monocot plants, but D. fangzhongdai strains have also been isolated from pear trees and water sources. Here, we analysed which genetic novelty exists in this new species, what are the D. fangzhongdai-specific traits and what is the intra-specific diversity. Results The genomes of eight D. fangzhongdai strains isolated from diverse environments were compared to 31 genomes of strains belonging to other Dickeya species. The D. fangzhongdai core genome regroups approximately 3500 common genes, including most genes that encode virulence factors and regulators characterised in the D. dadantii 3937 model strain. Only 38 genes are present in D. fangzhongdai and absent in all other Dickeyas. One of them encodes a pectate lyase of the PL10 family of polysaccharide lyases that is found only in a few bacteria from the plant environment, soil or human gut. Other D. fangzhongdai-specific genes with a known or predicted function are involved in regulation or metabolism. The intra-species diversity analysis revealed that seven of the studied D. fangzhongdai strains were grouped into two distinct clades. Each clade possesses a pool of 100–150 genes that are shared by the clade members, but absent from the other D. fangzhongdai strains and several of these genes are clustered into genomic regions. At the strain level, diversity resides mainly in the arsenal of T5SS- and T6SS-related toxin-antitoxin systems and in secondary metabolite biogenesis pathways. Conclusion This study identified the genome-specific traits of the new D. fangzhongdai species and highlighted the intra-species diversity of this species. This diversity encompasses secondary metabolites biosynthetic pathways and toxins or the repertoire of genes of extrachromosomal origin. We however didn’t find any relationship between gene content and phenotypic differences or sharing of environmental habitats. Background Soft rot Pectobacteriaceae are Enterobacterales responsible for considerable economic losses in several important crops and ornamental plants [1,2,3]. Their virulence is mainly due to the production and secretion of a battery of plant cell wall degrading enzymes (PCWDEs) that cause maceration of the plant tissue; however, several other virulence factors have also been characterized [2, 4]. These bacteria often exhibit a very broad host range, and recent outbreaks in potato, for example, resulted from the action of a cohort of bacteria belonging to different Pectobacteriaceae species in a complex population dynamics history [5]. The Pectobacteriaceae family includes two genera comprising soft rot bacteria, Pectobacterium and Dickeya. The Dickeya genus was formed in 2005 by the reclassification of former Erwinia chrysanthemi into six species [6]. It has recently undergone multiple phylogenetic changes, including the addition of three new species, Dickeya solani [7], Dickeya aquatica [8] and, more recently, Dickeya fangzhongdai [9]. The description of this last new species was based on three isolates from pear trees in China with bleeding canker necrosis [9], but it was extended by a large number of strains isolated from monocot plants from Japan [10, 11]. D. fangzhongdai strains were associated with soft rot symptoms of many ornamental and economically important staple food plants [10, 12, 13], thereby highlighting the broad host range of the species. While there is little information regarding associated economic damages and the extent of its occurrence in different host plants outside of Asia, Alič et al. [14] recently identified D. fangzhongdai as the causative agent of soft rot of orchids in commercial production in Europe, starting with material from Asia [11]. Moreover, as previously reported, bacteriophages of different families, and active against D. fangzhongdai, were isolated from a wastewater treatment plant not associated to the orchid production site. This would suggest that D. fangzhongdai bacteria may be more widespread in nature than could currently be concluded on the basis of symptoms in plants. Its occurrence in water would suggest that it may potentially have a wider ecological niche than genomically close Dickeya spp., that is, Dickeya dadantii, Dickeya dianthicola, and D. solani. Previous experience with D. solani has shown that novel species or isolates can lead to clonal spread and high losses in affected host plants [15]. Together with repeated introductions of D. fangzhongdai, the co-occurrence of genetically and phenotypically diverse strains on the same plants (e.g., B16 and S1 on orchids, as reported by Alič et al. [11]) increases the probability of the development of recombined strains with novel pathogenic potential and may present a risk to agriculturally important plants. Their aggressiveness, high maceration potential on various plant tissues, and persistence in potato plants further exacerbate the risk for agriculture. Therefore, in this paper, we analysed the genomic characteristics of the D. fangzhongdai species, compared it to the other Dickeya species and determine the inter- and intra- species diversity. The study addressed the question whether the presence of the isolates in a specific environment is associated to a specific set of genes (water vs plant symptoms, monocots vs dicots, different geographical origin). We also analysed the virulence gene arsenal, in order to evaluate the virulence potential of this species. Methods Dickeya strain selection All D. fangzhongdai genomes publicly available in the NCBI database were included in this study. These genomes were compared to five D. solani, four D. dadantii, five D. dianthicola, five D. chrysanthemi, seven D. zeae, one D. aquatica, two D. paradisiaca and two unassigned Dickeya genomes extracted from the NCBI database. Information on the provenance and genomic data of the D. fangzhongdai strains used in this study are summarized in Table 1. The accession numbers and phylogenetic position of the other Dickeya strains used for the SiLix analyses are presented in Additional file 1: Figure S1.
Keywords: T5SS, T6SS, NRPS/PKS, zeamine, oocydin A, plant-bacteria interactions, plasmid, Dickeya fangzhongdai
Published in DiRROS: 23.07.2024; Views: 347; Downloads: 214
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1392.
Poročilo o preskusu št.: LVG 2024-055 : vzorec št. 2024/00136
Tine Hauptman, Špela Hočevar, Zina Devetak, Barbara Piškur, 2024, expertise, arbitration decision

Keywords: varstvo gozdov, morfološke analize, program preiskav, Geosmithia morbida, bolezen tisočerih rakov, vektorji, rtPCR
Published in DiRROS: 23.07.2024; Views: 324; Downloads: 0
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1393.
Biogeography of the Caribbean Cyrtognatha spiders
Klemen Čandek, Ingi Agnarsson, Greta Binford, Matjaž Kuntner, 2019, original scientific article

Abstract: Island systems provide excellent arenas to test evolutionary hypotheses pertaining to gene flow and diversification of dispersal-limited organisms. Here we focus on an orbweaver spider genus Cyrtognatha (Tetragnathidae) from the Caribbean, with the aims to reconstruct its evolutionary history, examine its biogeographic history in the archipelago, and to estimate the timing and route of Caribbean colonization. Specifically, we test if Cyrtognatha biogeographic history is consistent with an ancient vicariant scenario (the GAARlandia landbridge hypothesis) or overwater dispersal. We reconstructed a species level phylogeny based on one mitochondrial (COI) and one nuclear (28S) marker. We then used this topology to constrain a time-calibrated mtDNA phylogeny, for subsequent biogeographical analyses in BioGeoBEARS of over 100 originally sampled Cyrtognatha individuals, using models with and without a founder event parameter. Our results suggest a radiation of Caribbean Cyrtognatha, containing 11 to 14 species that are exclusively single island endemics. Although biogeographic reconstructions cannot refute a vicariant origin of the Caribbean clade, possibly an artifact of sparse outgroup availability, they indicate timing of colonization that is much too recent for GAARlandia to have played a role. Instead, an overwater colonization to the Caribbean in mid-Miocene better explains the data. From Hispaniola, Cyrtognatha subsequently dispersed to, and diversified on, the other islands of the Greater, and Lesser Antilles. Within the constraints of our island system and data, a model that omits the founder event parameter from biogeographic analysis is less suitable than the equivalent model with a founder event.
Keywords: biogeography, spiders
Published in DiRROS: 23.07.2024; Views: 323; Downloads: 230
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1394.
Stress-tolerant yeasts : opportunistic pathogenicity versus biocontrol potential
Janja Zajc, Cene Gostinčar, Anja Černoša, Nina Gunde-Cimerman, 2019, original scientific article

Abstract: Stress-tolerant fungi that can thrive under various environmental extremes are highly desirable for their application to biological control, as an alternative to chemicals for pest management. However, in fungi, the mechanisms of stress tolerance might also have roles in mammal opportunism. We tested five species with high biocontrol potential in agriculture (Aureobasidium pullulans, Debayomyces hansenii, Meyerozyma guilliermondii, Metschnikowia fructicola, Rhodotorula mucilaginosa) and two species recognized as emerging opportunistic human pathogens (Exophiala dermatitidis, Aureobasidium melanogenum) for growth under oligotrophic conditions and at 37 °C, and for tolerance to oxidative stress, formation of biofilms, production of hydrolytic enzymes and siderophores, and use of hydrocarbons as sole carbon source. The results show large overlap between traits desirable for biocontrol and traits linked to opportunism (growth under oligotrophic conditions, production of siderophores, high oxidative stress tolerance, and specific enzyme activities). Based on existing knowledge and these data, we suggest that oligotrophism and thermotolerance together with siderophore production at 37 °C, urease activity, melanization, and biofilm production are the main traits that increase the potential for fungi to cause opportunistic infections in mammals. These traits should be carefully considered when assessing safety of potential biocontrol agents.
Keywords: opportunistic pathogen, biocontrol agent, virulence, stress tolerance, secretome, CAZy, protease, thermotolerance, oligotrophism, melanin, siderophore, biofilm
Published in DiRROS: 23.07.2024; Views: 342; Downloads: 252
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1395.
Bacteria associated with moon jellyfish during bloom and post-bloom periods in the Gulf of Trieste (northern Adriatic)
Maja Kos Kramar, Tinkara Tinta, Davor Lučić, Alenka Malej, Valentina Turk, 2019, original scientific article

Abstract: Jellyfish are a prominent component of the plankton community. They frequently form conspicuous blooms which may interfere with different human enterprises. Among the aspects that remain understudied are jellyfish associations with microorganisms having potentially important implications for organic matter cycling. To the best of our knowledge, this study is the first to investigate the bacterial community associated with live moon jellyfish (Aurelia solida, Scyohozoa) in the Adriatic Sea. Using 16S rRNA clone libraries and culture-based methods, we have analyzed the bacterial community composition of different body parts: the exumbrella surface, oral arms, and gastric cavity, and investigated possible differences in medusa-associated bacterial community structure at the time of the jellyfish population peak, and during the senescent phase at the end of bloom. Microbiota associated with moon jellyfish was different from ambient seawater bacterial assemblage and varied between different body parts. Betaproteobacteria (Burkholderia, Cupriavidus and Achromobacter) dominated community in the gastral cavity of medusa, while Alphaproteobacteria (Phaeobacter, Ruegeria) and Gammaproteobacteria (Stenotrophomonas, Alteromonas, Pseudoalteromonas and Vibrio) prevailed on ‘outer’ body parts. Bacterial community structure changed during senescent phase, at the end of the jellyfish bloom, showing an increased abundance of Gammaproteobacteria, exclusively Vibrio. The results of cultured bacterial isolates showed the dominance of Gammaproeteobacteria, especially Vibrio and Pseudoalteromonas in all body parts. Our results suggest that jellyfish associated bacterial community might have an important role for the host, and that anthropogenic pollution in the Gulf of Trieste might affect their community structure.
Keywords: bacteria, moon jellyfish, Gulf of Trieste, Adriatic sea
Published in DiRROS: 23.07.2024; Views: 346; Downloads: 237
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1396.
Arthropod communities in fungal fruitbodies are weakly structured by climate and biogeography across European beech forests
Nicolas Friess, Jörg C. Müller, Pablo Aramendi, Claus Bässler, Martin P. Brändle, Christophe Bouget, Antoine Brin, Heinz Bussler, Kostadin B. Georgiev, Radosław Gil, Martin M. Gossner, Jacob Heilmann-Clausen, Gunnar Isacsson, Anton Krištín, Thibault Lachat, Laurent Larrieu, Elodie Magnanou, Alexander Maringer, Ulrich Mergner, Martin Mikoláš, Lars Opgenoorth, Jürgen Schmidl, Miroslav Svoboda, Simon Thorn, Kris Vandekerkhove, Al Vrezec, Thomas Wagner, Maria-Barbara Winter, Livia Zapponi, Roland Brandl, Sebastian Seibold, 2019, original scientific article

Abstract: Aim The tinder fungus Fomes fomentarius is a pivotal wood decomposer in European beech Fagus sylvatica forests. The fungus, however, has regionally declined due to centuries of logging. To unravel biogeographical drivers of arthropod communities associated with this fungus, we investigated how space, climate and habitat amount structure alpha and beta diversity of arthropod communities in fruitbodies of F. fomentarius. Location Temperate zone of Europe. Taxon Arthropods. Methods We reared arthropods from fruitbodies sampled from 61 sites throughout the range of European beech and identified 13 orders taxonomically or by metabarcoding. We estimated the total number of species occurring in fruitbodies of F. fomentarius in European beech forests using the Chao2 estimator and determined the relative importance of space, climate and habitat amount by hierarchical partitioning for alpha diversity and generalized dissimilarity models for beta diversity. A subset of fungi samples was sequenced for identification of the fungus’ genetic structure. Results The total number of arthropod species occurring in fruitbodies of F. fomentarius across European beech forests was estimated to be 600. Alpha diversity increased with increasing fruitbody biomass; it decreased with increasing longitude, temperature and latitude. Beta diversity was mainly composed by turnover. Patterns of beta diversity were only weakly linked to space and the overall explanatory power was low. We could distinguish two genotypes of F. fomentarius, which showed no spatial structuring. Main conclusion Fomes fomentarius hosts a large number of arthropods in European beech forests. The low biogeographical and climatic structure of the communities suggests that fruitbodies represent a habitat that offers similar conditions across large gradients of climate and space, but are characterized by high local variability in community composition and colonized by species with high dispersal ability. For European beech forests, retention of trees with F. fomentarius and promoting its recolonization where it had declined seems a promising conservation strategy.
Keywords: dead wood, insects, invertebrates, restoration, saproxylic, sporocarp
Published in DiRROS: 23.07.2024; Views: 558; Downloads: 202
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1397.
Poročilo o preskusu št.: LVG 2024-073 : vzorec št. 2024/00305
Nikica Ogris, Špela Hočevar, Barbara Piškur, 2024, expertise, arbitration decision

Keywords: varstvo gozdov, morfološke analize
Published in DiRROS: 23.07.2024; Views: 279; Downloads: 84
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1398.
MapMan4 : a refined protein classification and annotation framework applicable to multi-omics data analysis
Rainer Schwacke, Gabriel Y. Ponce-Soto, Kirsten Krause, Anthony M. Bolger, Borjana Arsova, Asis Hallab, Kristina Gruden, Mark Stitt, Marie E. Bolger, Björn Usadel, 2019, original scientific article

Abstract: Genome sequences from over 200 plant species have already been published, with this number expected to increase rapidly due to advances in sequencing technologies. Once a new genome has been assembled and the genes identified, the functional annotation of their putative translational products, proteins, using ontologies is of key importance as it places the sequencing data in a biological context. Furthermore, to keep pace with rapid production of genome sequences, this functional annotation process must be fully automated. Here we present a redesigned and significantly enhanced MapMan4 framework, together with a revised version of the associated online Mercator annotation tool. Compared with the original MapMan, the new ontology has been expanded almost threefold and enforces stricter assignment rules. This framework was then incorporated into Mercator4, which has been upgraded to reflect current knowledge across the land plant group, providing protein annotations for all embryophytes with a comparably high quality. The annotation process has been optimized to allow a plant genome to be annotated in a matter of minutes. The output results continue to be compatible with the established MapMan desktop application.
Keywords: genome sequences, MapMan4
Published in DiRROS: 23.07.2024; Views: 362; Downloads: 253
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1399.
Microscopy of crustacean cuticle : formation of a flexible extracellular matrix in moulting sea slaters Ligia pallasii
Jasna Štrus, Magda Tušek-Žnidarič, Urška Repnik, Andrej Blejec, Adam P. Summers, 2019, original scientific article

Abstract: Structural and functional properties of exoskeleton in moulting sea slaters Ligia pallasii from the Eastern Pacific coast were investigated with CT scanning and electron microscopy. Ultrastructure of preecdysial and postecdysial cuticular layers was described in premoult, intramoult and postmoult animals. Cuticle is a flexible extracellular matrix connected to the epidermal cells through pore channels. During premoult epicuticle and exocuticle are formed and during intramoult and postmoult endocuticular lamellae are deposited and the cuticle is progressively constructed by thickening and mineralization. Cuticle permeability, flexibility and waterproofing capacity change accordingly. Elaboration of epicuticular scales connected to an extensive network of nanotubules, establish its anti-adhesive and hydrophobic properties. Labelling with gold conjugated WGA lectins on Tokuyashu thawed cryosections exposes differences in chitin content between exocuticle and endocuticle. Histochemical staining of cuticle shows presence of acidic carbohydrates/glycoconjugates and lipoproteins in epicuticular layer. Chitin microfibrils are formed at the microvillar border of epidermal cells with abundant Golgi apparatus and secretory vesicles. Numerous spherules associated with nanotubules were observed in the ecdysial space in intramoult animals. The mineral component of the cuticle as visualized with CT scanning indicates progressive mineral resorption from the posterior to the anterior half of the body in premoult animals, its translocation from the anterior to posterior part during intramoult and its progressive deposition in the posterior and anterior exoskeleton during postmoult. Cuticle of sea slaters is a unique biocomposite and biodynamic material constantly reconstructed during frequent moults, and adapted to specific physical and biotic conditions of the high intertidal rocky zone.
Keywords: cuticle ultrastructure, micro CT scanning, moult cycle, SEM, TEM, terrestrial isopods
Published in DiRROS: 23.07.2024; Views: 445; Downloads: 349
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1400.
Poročilo o preskusu št.: LVG 2024-069 : vzorec št. 2024/00338/MdG
Maarten De Groot, 2024, expertise, arbitration decision

Keywords: varstvo gozdov, morfološke analize
Published in DiRROS: 23.07.2024; Views: 254; Downloads: 0
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