scholarly journals Towards the Forest Virome: Next-Generation-Sequencing Drastically Expands our Understanding on Virosphere in Temperate Forest Ecosystems

Author(s):  
Artemis Rumbou ◽  
Eeva J. Vainio ◽  
Carmen Büttner

Forest health is dependent on the variability of microorganisms interacting with the host tree/holobiont. Symbiotic microbiota and pathogens engage in a permanent interplay, which influences the host. Thanks to the development of NGS technologies, a vast amount of genetic information on the virosphere of temperate forests has been gained the last seven years. To estimate the qualitative/quantitative impact of NGS in forest virology, we have summarized viruses affecting major tree/shrub species and their fungal associates, including fungal plant pathogens, mutualists and saprotrophs. The contribution of NGS methods is extremely significant for forest virology. Reviewed data about viral presence in holobionts, allowed us to address the role of the virome in the holobionts. Genetic variation is a crucial aspect in hologenome, significantly reinforced by horizontal gene transfer among all interacting actors. Through virus-virus interplays synergistic or antagonistic relations may evolve, which may drastically affect the health of the holobiont. Novel insights of these interplays may allow practical applications for forest plant protection based on endophytes and mycovirus biocontrol agents. The current analysis is conceived in light of the prospect that novel viruses may initiate an emergent infectious disease and that measures for avoidance of future outbreaks in forests should be considered.

2021 ◽  
Vol 9 (8) ◽  
pp. 1730
Author(s):  
Artemis Rumbou ◽  
Eeva J. Vainio ◽  
Carmen Büttner

Thanks to the development of HTS technologies, a vast amount of genetic information on the virosphere of temperate forests has been gained in the last seven years. To estimate the qualitative/quantitative impact of HTS on forest virology, we have summarized viruses affecting major tree/shrub species and their fungal associates, including fungal plant pathogens, mutualists and saprotrophs. The contribution of HTS methods is extremely significant for forest virology. Reviewed data on viral presence in holobionts allowed us a first attempt to address the role of virome in holobionts. Forest health is dependent on the variability of microorganisms interacting with the host tree/holobiont; symbiotic microbiota and pathogens engage in a permanent interplay, which influences the host. Through virus–virus interplays synergistic or antagonistic relations may evolve, which may drastically affect the health of the holobiont. Novel insights of these interplays may allow practical applications for forest plant protection based on endophytes and mycovirus biocontrol agents. The current analysis is conceived in light of the prospect that novel viruses may initiate an emergent infectious disease and that measures for the avoidance of future outbreaks in forests should be considered.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marta Matuszewska ◽  
Tomasz Maciąg ◽  
Magdalena Rajewska ◽  
Aldona Wierzbicka ◽  
Sylwia Jafra

AbstractPseudomonas donghuensis P482 is a tomato rhizosphere isolate with the ability to inhibit growth of bacterial and fungal plant pathogens. Herein, we analysed the impact of the carbon source on the antibacterial activity of P482 and expression of the selected genes of three genomic regions in the P482 genome. These regions are involved in the synthesis of pyoverdine, 7-hydroxytropolone (7-HT) and an unknown compound (“cluster 17”) and are responsible for the antimicrobial activity of P482. We showed that the P482 mutants, defective in these regions, show variations and contrasting patterns of growth inhibition of the target pathogen under given nutritional conditions (with glucose or glycerol as a carbon source). We also selected and validated the reference genes for gene expression studies in P. donghuensis P482. Amongst ten candidate genes, we found gyrB, rpoD and mrdA the most stably expressed. Using selected reference genes in RT-qPCR, we assessed the expression of the genes of interest under minimal medium conditions with glucose or glycerol as carbon sources. Glycerol was shown to negatively affect the expression of genes necessary for 7-HT synthesis. The significance of this finding in the light of the role of nutrient (carbon) availability in biological plant protection is discussed.


2007 ◽  
Vol 73 (9) ◽  
pp. 2820-2824 ◽  
Author(s):  
Tyler J. Avis ◽  
Mélanie Michaud ◽  
Russell J. Tweddell

ABSTRACT Aluminum chloride and sodium metabisulfite have shown high efficacy at low doses in controlling postharvest pathogens on potato tubers. Direct effects of these two salts included the loss of cell membrane integrity in exposed pathogens. In this work, four fungal potato pathogens were studied in order to elucidate the role of membrane lipids and lipid peroxidation in the relative sensitivity of microorganisms exposed to these salts. Inhibition of mycelial growth in these fungi varied considerably and revealed sensitivity groups within the tested fungi. Analysis of fatty acids in these fungi demonstrated that sensitivity was related to high intrinsic fatty acid unsaturation. When exposed to the antifungal salts, sensitive fungi demonstrated a loss of fatty acid unsaturation, which was accompanied by an elevation in malondialdehyde content (a biochemical marker of lipid peroxidation). Our data suggest that aluminum chloride and sodium metabisulfite could induce lipid peroxidation in sensitive fungi, which may promote the ensuing loss of integrity in the plasma membrane. This direct effect on fungal membranes may contribute, at least in part, to the observed antimicrobial effects of these two salts.


2021 ◽  
Author(s):  
Christopher A Brosnan ◽  
Anne Sawyer ◽  
Filipe Fenselau Felippes ◽  
Bernard J Carroll ◽  
Peter M Waterhouse ◽  
...  

Topical application of double-stranded RNA (dsRNA) as RNA interference(RNAi) based biopesticides represents a sustainable alternative to traditional transgenic, breeding-based or chemical crop protection strategies. A key feature of RNAi is its ability to act non-cell autonomously, a process that plays a critical role in plant protection. However, the uptake of dsRNA upon topical application, and its ability to move and act non-cell autonomously remains debated and largely unexplored. Here we show that when applied to a leaf, unprocessed full-length dsRNA enters the vasculature and rapidly moves to multiple distal below ground, vegetative and reproductive tissue types in several model plant and crop hosts. Intact unprocessed dsRNA was detected in the apoplast of leaves, roots and flowers after leaf application and maintained in subsequent new growth. Furthermore, we show mobile dsRNA is functional against root infecting fungal and foliar viral pathogens. Our demonstration of the uptake and maintained movement of intact and functional dsRNA stands to add significant benefit to the emerging field of RNAi-based plant protection.


Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4858
Author(s):  
Stefano De Benedetti ◽  
Valeria Girlando ◽  
Matias Pasquali ◽  
Alessio Scarafoni

Okara is a soybean transformation agri-food by-product, the massive production of which currently poses severe disposal issues. However, its composition is rich in seed storage proteins, which, once extracted, can represent an interesting source of bioactive peptides. Antimicrobial and antifungal proteins and peptides have been described in plant seeds; thus, okara is a valuable source of compounds, exploitable for integrated pest management. The aim of this work is to describe a rapid and economic procedure to isolate proteins from okara, and to produce an enzymatic proteolyzed product, active against fungal plant pathogens. The procedure allowed the isolation and recovery of about 30% of okara total proteins. Several proteolytic enzymes were screened to identify the proper procedure to produce antifungal compounds. Antifungal activity of the protein digested for 24 h with pancreatin against Fusarium and R. solani mycelial growth and Pseudomonas spp was assessed. A dose-response inhibitory activity was established against fungi belonging to the Fusarium genus. The exploitation of okara to produce antifungal bioactive peptides has the potential to turn this by-product into a paradigmatic example of circular economy, since a field-derived food waste is transformed into a source of valuable compounds to be used in field crops protection.


2021 ◽  
pp. 33-86
Author(s):  
Wagner Bettiol ◽  
◽  
Flávio Henrique Vasconcelos de Medeiros ◽  
Josiane Barros Chiaramonte ◽  
Rodrigo Mendes ◽  
...  

The success of a biological control programme depends on the isolation and selection of antagonists. There is an enormous diversity of culturable microbial species in the soil, rhizosphere, phylloplane, spermosphere and carposphere, which can be used in the isolation and selection of antagonists. The structures of fungal plant pathogens concerned with survival and infection may also be sources of antagonists. Although non-culturable microorganisms and microbiome-based strategies have great potential for development as commercial products in disease control, more knowledge is needed to understand the mechanisms involved in interactions between plants and complex microbial communities. Methods of isolation and selection of the most commercially exploited groups of antagonists and their advantages and disadvantages are discussed in this chapter as well as those of non-traditional antagonists. Finally, possible strategies for engineering the soil and host microbiome to actively promote plant protection against pathogens are discussed.


mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Lukas Meile ◽  
Jules Peter ◽  
Guido Puccetti ◽  
Julien Alassimone ◽  
Bruce A. McDonald ◽  
...  

ABSTRACT Dynamic changes in transcription profiles are key for the success of pathogens in colonizing their hosts. In many pathogens, genes associated with virulence, such as effector genes, are located in regions of the genome that are rich in transposable elements and heterochromatin. The contribution of chromatin modifications to gene expression in pathogens remains largely unknown. Using a combination of a reporter gene-based approach and chromatin immunoprecipitation, we show that the heterochromatic environment of effector genes in the fungal plant pathogen Zymoseptoria tritici is a key regulator of their specific spatiotemporal expression patterns. Enrichment in trimethylated lysine 27 of histone H3 dictates the repression of effector genes in the absence of the host. Chromatin decondensation during host colonization, featuring a reduction in this repressive modification, indicates a major role for epigenetics in effector gene induction. Our results illustrate that chromatin modifications triggered during host colonization determine the specific expression profile of effector genes at the cellular level and, hence, provide new insights into the regulation of virulence in fungal plant pathogens. IMPORTANCE Fungal plant pathogens possess a large repertoire of genes encoding putative effectors, which are crucial for infection. Many of these genes are expressed at low levels in the absence of the host but are strongly induced at specific stages of the infection. The mechanisms underlying this transcriptional reprogramming remain largely unknown. We investigated the role of the genomic environment and associated chromatin modifications of effector genes in controlling their expression pattern in the fungal wheat pathogen Zymoseptoria tritici. Depending on their genomic location, effector genes are epigenetically repressed in the absence of the host and during the initial stages of infection. Derepression of effector genes occurs mainly during and after penetration of plant leaves and is associated with changes in histone modifications. Our work demonstrates the role of chromatin in shaping the expression of virulence components and, thereby, the interaction between fungal pathogens and their plant hosts.


2003 ◽  
Vol 83 (Special Issue) ◽  
pp. 331-336 ◽  
Author(s):  
R. D. Reeleder

The role of biodiversity as it affects the control of soil-borne fungal pathogens is discussed. Soil-borne fungal plant pathogens have often proven difficult to manage with conventional methods of disease control. Nonetheless, researchers have characterized several naturally occurring “disease-suppressive” soils where crop loss from disease is less than would otherwise be expected. Suppressive soils can also result from the incorporation of various amendments into soil. In most cases, disease control in such soils has been shown to be biological in nature; that is, soil organisms appear to directly or indirectly inhibit the development of disease. Increased knowledge of the identity and functioning of these organisms may support the development of techniques that can be used to develop suppressiveness in soils that are otherwise disease-conducive. Populations of pathogens themselves have been shown to exhibit considerable genetic diversity; the ability of populations to respond to disease control measures should be considered when developing a management strategy. New molecular techniques can be exploited to better characterize soil communities, including the pathogens themselves, as well as community responses to various disease control options. The contributions of Canadian researchers to these areas are discussed and models for further study are proposed. Key words: Biocontrol, molecular technologies, functional diversity, integrated pest management


2021 ◽  
Author(s):  
Marta Matuszewska ◽  
Tomasz Maciag ◽  
Magdalena Rajewska ◽  
Aldona Wierzbicka ◽  
Sylwia Jafra

Abstract Pseudomonas donghuensis P482 is a tomato rhizosphere isolate with the ability to inhibit growth of bacterial and fungal plant pathogens. Herein, we analysed the impact of the carbon source on the antibacterial activity of P482 and expression of the selected genes of three genomic regions in the P482 genome. These regions are involved in the synthesis of pyoverdine, 7‑hydroxytropolone (7-HT) and an unknown compound (“cluster 17”) and are responsible for antimicrobial activity of P482. We showed that the P482 mutants, defective in these regions, show variations and contrasting patterns of growth inhibition of the target pathogen under given nutritional conditions (with glucose or glycerol as a carbon source). We also selected and validated the reference genes for gene expression studies in P. donghuensis P482. Amongst ten candidate genes, we found gyrB, rpoD and mrdA the most stably expressed. Using selected reference genes in RT-qPCR, we assessed the expression of the genes of interest under minimal medium conditions with glucose or glycerol as carbon sources. Glycerol was shown to negatively affect the expression of genes necessary for 7-HT synthesis. The significance of this finding in the light of the role of nutrient (carbon) availability in biological plant protection is discussed.


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