scholarly journals The role of Dicer-dependent RNA interference in regulating cross-species communication during fungus-fungus interactions

2021 ◽  
Author(s):  
Edoardo Piombo ◽  
Ramesh Raju Vetukuri ◽  
Anders Broberg ◽  
Pruthvi B Kalyandurg ◽  
Sandeep Kushwaha ◽  
...  
Keyword(s):  
Rna Interference ◽  
Pathogenic Fungus ◽  
Hydrolytic Enzymes ◽  
Plant Diseases ◽  
Parasitic Fungus ◽  
Transcriptional Gene Silencing ◽  
Clonostachys Rosea ◽  
Stem Loop

Dicer-like (DCL) proteins play a vital role in transcriptional and post-transcriptional gene silencing, also known as RNA interference (RNAi), by cleaving double-stranded RNAs or single-stranded RNAs with stem-loop structures into small RNAs . Although DCL-mediated RNAi can regulate interspecific communication between pathogenic/mutualistic organisms and their hosts, its role in parasitic fungus-fungus interactions is yet to be investigated . In this study, we deleted dcl genes in the mycoparasitic fungus Clonostachys rosea and analyzed the transcriptome and secondary metabolome to characterize the regulatory functions of DCL-dependent RNAi in mycoparasitism. Deletion of dcl2 resulted in a mutant with reduced growth rate, pigment production and antagonism towards the plant pathogenic fungus Botrytis cinerea . Moreover, the Δ dcl2 mutant displayed a reduced ability to control fusarium foot rot disease on wheat, caused by Fusarium graminearum , and reduced production of 62 secondary metabolites (SM) including yellow‐coloured sorbicillinoids. Transcriptome sequencing of the in vitro interaction between the C. rosea Δ dcl2 strain and B. cinerea or F. graminearum identified downregulation of genes coding for transcription factors, membrane transporters, hydrolytic enzymes and SM biosynthesis enzymes putatively involved in antagonistic interactions, in comparison with the C. rosea wild type interaction. Sixty-one putative novel microRNA-like RNAs (milRNAs) were identified in C. rosea , and 11 was upregulated in the Δ dcl2 mutant. In addition to putative endogenous gene targets, these DCL2-dependent milRNAs were predicted to target B . cinerea and F. graminearum virulence factor genes, which showed an increased expression during interaction with the Δ dcl2 mutant incapable of producing the targeting milRNAs. This paper constitutes the first step in elucidating the role of RNAi in mycoparasitism, with important implications for biological control of plant diseases. This study further indicates a possible cross-species regulatory activity of fungal milRNAs, emphasizing a novel role of RNAi in fungal interactions and ecology.

scholarly journals Viroids as a Tool to Study RNA-Directed DNA Methylation in Plants

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1187
Author(s):  
Michael Wassenegger ◽  
Athanasios Dalakouras
Keyword(s):  
Dna Methylation ◽  
Rna Interference ◽  
Gene Silencing ◽  
Plant Cells ◽  
Transcriptional Gene Silencing ◽  
Rnai Machinery ◽  
Double Stranded Rna ◽  
Post Transcriptional Gene Silencing ◽  
Cumulative Amount

Viroids are plant pathogenic, circular, non-coding, single-stranded RNAs (ssRNAs). Members of the Pospiviroidae family replicate in the nucleus of plant cells through double-stranded RNA (dsRNA) intermediates, thus triggering the host’s RNA interference (RNAi) machinery. In plants, the two RNAi pillars are Post-Transcriptional Gene Silencing (PTGS) and RNA-directed DNA Methylation (RdDM), and the latter has the potential to trigger Transcriptional Gene Silencing (TGS). Over the last three decades, the employment of viroid-based systems has immensely contributed to our understanding of both of these RNAi facets. In this review, we highlight the role of Pospiviroidae in the discovery of RdDM, expound the gradual elucidation through the years of the diverse array of RdDM’s mechanistic details and propose a revised RdDM model based on the cumulative amount of evidence from viroid and non-viroid systems.

Immunomodulation by 17β-estradiol in bivalve hemocytes

2006 ◽  
Vol 291 (3) ◽  
pp. R664-R673 ◽  
Author(s):  
Laura Canesi ◽  
Caterina Ciacci ◽  
Lucia Cecilia Lorusso ◽  
Michele Betti ◽  
Tiziana Guarnieri ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Hydrolytic Enzymes ◽  
Physiological Role ◽  
Estrogen Receptor Α ◽  
Nitrite Accumulation ◽  
No Production ◽  
17Β Estradiol

In mammals, estrogens have dose- and cell-type-specific effects on immune cells and may act as pro- and anti-inflammatory stimuli, depending on the setting. In the bivalve mollusc Mytilus, the natural estrogen 17β-estradiol (E2) has been shown to affect neuroimmune functions. We have investigated the immunomodulatory role of E2 in Mytilus hemocytes, the cells responsible for the innate immune response. E2 at 5–25 nM rapidly stimulated phagocytosis and oxyradical production in vitro; higher concentrations of E2 inhibited phagocytosis. E2-induced oxidative burst was prevented by the nitric oxide (NO) synthase inhibitor NG-monomethyl-l-arginine and superoxide dismutase, indicating involvement of NO and O2−; NO production was confirmed by nitrite accumulation. The effects of E2 were prevented by the antiestrogen tamoxifen and by specific kinase inhibitors, indicating a receptor-mediated mechanism and involvement of p38 MAPK and PKC. E2 induced rapid and transient increases in the phosphorylation state of PKC, as well as of a aCREB-like (cAMP responsive element binding protein) transcription factor, as indicated by Western blot analysis with specific anti-phospho-antibodies. Localization of estrogen receptor-α- and -β-like proteins in hemocytes was investigated by immunofluorescence confocal microscopy. The effects of E2 on immune function were also investigated in vivo at 6 and 24 h in hemocytes of E2-injected mussels. E2 significantly affected hemocyte lysosomal membrane stability, phagocytosis, and extracellular release of hydrolytic enzymes: lower concentrations of E2 resulted in immunostimulation, and higher concentrations were inhibitory. Our data indicate that the physiological role of E2 in immunomodulation is conserved from invertebrates to mammals.

scholarly journals Functional characterization of the AGL1 aegerolysin in the mycoparasitic fungus Trichoderma atroviride reveals a role in conidiation and antagonism

2020 ◽  
Author(s):  
Mukesh Dubey ◽  
Dan Funck Jensen ◽  
Magnus Karlsson
Keyword(s):  
Pathogenic Fungus ◽  
Functional Characterization ◽  
Fruit Body ◽  
Cellular Membrane ◽  
Plant Diseases ◽  
Wall Material ◽  
Trichoderma Atroviride ◽  
Phenotypic Analysis ◽  
Mycoparasitic Fungus

Abstract Aegerolysins are small secreted pore-forming proteins that are found in both prokaryotes and eukaryotes. The role of aegerolysins in sporulation, fruit body formation, and in lysis of cellular membrane is suggested in fungi. The aim of the present study was to characterize the biological function of the aegerolysin gene agl1 in the mycoparasitic fungus Trichoderma atroviride, used for biological control of plant diseases. Gene expression analysis showed higher expression of agl1 during conidiation and during growth in medium supplemented with cell wall material from the plant pathogenic fungus Rhizoctonia solani as the sole carbon source. Expression of agl1 was supressed under iron-limiting condition, while agl1 transcript was not detected during T. atroviride interactions with the prey fungi Botrytis cinerea or R. solani. Phenotypic analysis of agl1 deletion strains (Δagl1) showed reduced conidiation compared to T. atroviride wild type, thus suggesting the involvement of AGL1 in conidiation. Furthermore, the Δagl1 strains display reduced antagonism towards B. cinerea and R. solani based on a secretion assay, although no difference was detected during direct interactions. These data demonstrate the role of AGL1 in conidiation and antagonism in the mycoparasitic fungus T. atroviride.

scholarly journals Deletion of Mid1, a putative stretch-activated calcium channel in Claviceps purpurea, affects vegetative growth, cell wall synthesis and virulence

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 3922-3933 ◽  
Author(s):  
Jörg Bormann ◽  
Paul Tudzynski
Keyword(s):  
Vegetative Growth ◽  
Pathogenic Fungus ◽  
Axenic Culture ◽  
Gene Replacement ◽  
Major Effect ◽  
Growth Defect ◽  
Claviceps Purpurea ◽  
Disease Symptoms

The putative Claviceps purpurea homologue of the Saccharomyces cerevisiae stretch-activated calcium ion channel Mid1 was investigated for its role in vegetative growth, differentiation and pathogenicity on rye (Secale cereale). Gene replacement mutants of Cl. purpurea mid1 were not affected in polar growth and branching in axenic culture but showed a significantly reduced growth rate. The growth defect could not be complemented by Ca2+ supplementation, in contrast to mid1 mutants in yeast, but the altered sensitivity of the mutants to changes in external and internal Ca2+ concentrations indicates some role of Mid1 in Ca2+ homeostasis. The major effect of mid1 deletion, however, was the complete loss of virulence: infected rye plants showed no disease symptoms at all. Detailed analyses of in vitro-infected rye ovaries demonstrated that the Δmid1 mutants had multiple apical branches and were unable to infect the host tissue, suggesting that Mid1 is essential for generating the necessary mechanical force for penetration. This is believed to be the first report of an essential role for a Mid1 homologue in the virulence of a plant-pathogenic fungus.

scholarly journals RNA Interference Inhibition of Mus81 Reduces Mitotic Recombination in Human Cells

2004 ◽  
Vol 15 (2) ◽  
pp. 552-562 ◽  
Author(s):  
Veronique Blais ◽  
Hui Gao ◽  
Cherilyn A. Elwell ◽  
Michael N. Boddy ◽  
Pierre-Henri L. Gaillard ◽  
...  
Keyword(s):  
Rna Interference ◽  
Direct Evidence ◽  
Mitotic Recombination ◽  
Holliday Junctions ◽  
Replication Forks ◽  
Holliday Junction Resolvase ◽  
Substrate Cleavage

Mus81 is a highly conserved endonuclease with homology to the XPF subunit of the XPF-ERCC1 complex. In yeast Mus81 associates with a second subunit, Eme1 or Mms4, which is essential for endonuclease activity in vitro and for in vivo function. Human Mus81 binds to a homolog of fission yeast Eme1 in vitro and in vivo. We show that recombinant Mus81-Eme1 cleaves replication forks, 3′ flap substrates, and Holliday junctions in vitro. By use of differentially tagged versions of Mus81 and Eme1, we find that Mus81 associates with Mus81 and that Eme1 associates with Eme1. Thus, complexes containing two or more Mus81-Eme1 units could function to coordinate substrate cleavage in vivo. Down-regulation of Mus81 by RNA interference reduces mitotic recombination in human somatic cells. The recombination defect is rescued by expression of a bacterial Holliday junction resolvase. These data provide direct evidence for a role of Mus81-Eme1 in mitotic recombination in higher eukaryotes and support the hypothesis that Mus81-Eme1 resolves Holliday junctions in vivo.

scholarly journals The Fusarium graminearum t-SNARE Sso2 Is Involved in Growth, Defense, and DON Accumulation and Virulence

2020 ◽  
Vol 33 (7) ◽  
pp. 888-901
Author(s):  
Sean P. O’Mara ◽  
Karen Broz ◽  
Marike Boenisch ◽  
Zixuan Zhong ◽  
Yanhong Dong ◽  
...  
Keyword(s):  
Fusarium Graminearum ◽  
Deletion Mutant ◽  
Expression Profiles ◽  
Pathogenic Fungus ◽  
Gene Expression Profiles ◽  
Plant Diseases ◽  
In Planta ◽  
Head Blight ◽  
Double Deletion

The plant-pathogenic fungus Fusarium graminearum, causal agent of Fusarium head blight (FHB) disease on small grain cereals, produces toxic trichothecenes that require facilitated export for full virulence. Two potential modes of mycotoxin transport are membrane-bound transporters, which move toxins across cellular membranes, and N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-mediated vesicular transport, by which toxins may be packaged as cargo in vesicles bound for organelles or the plasma membrane. In this study, we show that deletion of a gene (Sso2) for a subapically localized t-SNARE protein results in growth alteration, increased sensitivity to xenobiotics, altered gene expression profiles, and reduced deoxynivalenol (DON) accumulation in vitro and in planta as well as reduced FHB symptoms on wheat. A double deletion mutant generated by crossing the ∆sso2 deletion mutant with an ATP-binding cassette transporter deletion mutant (∆abc1) resulted in an additive reduction in DON accumulation and almost complete loss of FHB symptoms in planta. These results suggest an important role of Sso2-mediated subapical exocytosis in FHB progression and xenobiotic defense and are the first report of an additive reduction in F. graminearum DON accumulation upon deletion of two distinct modes of cellular export. This research provides useful information which may aid in formulating novel management plans of FHB or other destructive plant diseases.

scholarly journals Salts Application for Suppressing Potato Early Blight Disease

2009 ◽  
Vol 49 (4) ◽  
pp. 353-361 ◽  
Author(s):  
Nehal El-Mougy ◽  
Mokhtar Abdel-Kader
Keyword(s):  
Sodium Bicarbonate ◽  
Calcium Chloride ◽  
Early Blight ◽  
Disease Incidence ◽  
Pathogenic Fungus ◽  
Fungal Growth ◽  
Plant Diseases ◽  
Effective Control ◽  
Blight Disease

Salts Application for Suppressing Potato Early Blight DiseaseThe suppressive effect of sodium and calcium salts applied individually or combined with the yeastSaccharomyces cerevisiaeagainstAlternaria solanithe causal agent of early blight disease of potato was evaluated under laboratory, greenhouse and field conditions.In vitrotest a complete inhibition in fungal growth was observed at concentration of 30 mg/ml of both sodium bicarbonate and calcium chloride. The commercial backing yeastS. cerevisiae(CBY) enhanced the inhibitory effect of tested salts reflected in increasing mycelial fungal growth reduction when combined at the rate of 1:1 at each concentration tested. In pot experiment, under artificial infestation with pathogenic fungus, application of sodium bicarbonate or calcium chloride significantly reduced the early blight incidence and severity by increasing their concentrations. Their most effective concentration were 30 mg/ml that reduced the disease incidence by 50 and 62.4%, respectively. Superior effect of sodium bicarbonate or calcium chloride in disease reduction was observed when they combined with CBY. Field trails for evaluating the most promising greenhouse treatments were preformed under natural infestations during two successive summer seasons. Calcium chloride proved higher efficacy for reducing both disease incidence and severity than that of sodium bicarbonate when applied either alone or combined with CBY. Also, it is observed that increasing concentrations of both sodium bicarbonate or calcium chloride showed parallel decrease in disease incidence and severity. Application of (CBY) enhanced the efficacy of salts spraying against early blight disease. Similar trend was also observed with the increase of potato tubers yield. On the light of the present study it could be suggested that the usage of combined application of the yeastS. cerevisiaewith sodium bicarbonate or calcium chloride might be used as easily applied, safely and cost effective control methods against such plant diseases.

scholarly journals Tilting the balance between RNA interference and replication eradicatesLeishmaniaRNA virus 1 and mitigates the inflammatory response

2016 ◽  
Vol 113 (43) ◽  
pp. 11998-12005 ◽  
Author(s):  
Erin A. Brettmann ◽  
Jahangheer S. Shaik ◽  
Haroun Zangger ◽  
Lon-Fye Lye ◽  
F. Matthew Kuhlmann ◽  
...  
Keyword(s):  
High Efficiency ◽  
Rna Virus ◽  
Rnai Pathway ◽  
Leishmania Braziliensis ◽  
Stem Loop ◽  
Mucocutaneous Leishmaniasis ◽  
Virus Retention ◽  
Dsrna Genome

ManyLeishmania(Viannia) parasites harbor the double-stranded RNA virusLeishmania RNA virus 1(LRV1), which has been associated with increased disease severity in animal models and humans and with drug treatment failures in humans. Remarkably, LRV1 survives in the presence of an active RNAi pathway, which in many organisms controls RNA viruses. We found significant levels (0.4 to 2.5%) of small RNAs derived from LRV1 in bothLeishmania braziliensisandLeishmania guyanensis, mapping across both strands and with properties consistent with Dicer-mediated cleavage of the dsRNA genome. LRV1 lackscis- ortrans-acting RNAi inhibitory activities, suggesting that virus retention must be maintained by a balance between RNAi activity and LRV1 replication. To tilt this balance toward elimination, we targeted LRV1 using long-hairpin/stem-loop constructs similar to those effective against chromosomal genes. LRV1 was completely eliminated, at high efficiency, accompanied by a massive overproduction of LRV1-specific siRNAs, representing as much as 87% of the total. For bothL. braziliensisandL. guyanensis, RNAi-derived LRV1-negative lines were no longer able to induce a Toll-like receptor 3–dependent hyperinflammatory cytokine response in infected macrophages. We demonstrate in vitro a role for LRV1 in virulence ofL. braziliensis, theLeishmaniaspecies responsible for the vast majority of mucocutaneous leishmaniasis cases. These findings establish a targeted method for elimination of LRV1, and potentially of otherLeishmaniaviruses, which will facilitate mechanistic dissection of the role of LRV1-mediated virulence. Moreover, our data establish a third paradigm for RNAi–viral relationships in evolution: one of balance rather than elimination.

scholarly journals Role of Epichloë Endophytes in Defense Responses of Cool-Season Grasses to Pathogens: A Review

Plant Disease ◽  
2018 ◽  
Vol 102 (11) ◽  
pp. 2061-2073 ◽  
Author(s):  
Chao Xia ◽  
Nana Li ◽  
Yawen Zhang ◽  
Chunjie Li ◽  
Xingxu Zhang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Fungal Endophytes ◽  
Animal Husbandry ◽  
Defense Responses ◽  
Economic Benefits ◽  
Plant Diseases ◽  
Cool Season ◽  
Physical Defense

Various cool-season grasses are infected by Epichloë endophyte, and this symbiotic relationship is always of benefit to the host grass due to an increased resistance to abiotic and biotic stresses. Fungal diseases adversely affect the yield, quality, and economic benefits of rangelands, which affects the production of animal husbandry. Therefore, it is imperative to breed resistant cultivars and to better understand the role of fungal endophytes in order to protect grasses against pathogens. The present review introduces research regarding how these endophytes affect the growth of pathogens in vitro and how they change the resistance of host plants to plant diseases. From the perspective of physical defense, changes in physiological indexes, and secretion of chemical compounds, we summarize the potential mechanisms by which endophytes are able to enhance the disease resistance of a host grass. Through these, we aim to establish a solid theoretical foundation for plant disease control and disease resistance breeding by application of fungal endophytes. A broader understanding of fungal endophyte effects on hosts could create a new opportunity for managing or introducing fungal symbioses in both agronomic or non-agronomic ecosystems.

VIRUS–HOST INTERACTIONS, WITH EMPHASIS ON CERTAIN CYTOPATHIC PHENOMENA

1967 ◽  
Vol 45 (8) ◽  
pp. 1221-1234 ◽  
Author(s):  
H. W. J. Ragetli
Keyword(s):  
Electron Microscopy ◽  
Rna Virus ◽  
Hydrolytic Enzymes ◽  
Symptom Expression ◽  
Plant Interactions ◽  
Host Interactions ◽  
Different Types ◽  
Virus Strains

The apparent role played by each participant in virus–plant interactions, as suggested by symptom expression, is discussed. To explain the markedly different reactions of identical hosts to closely related virus strains, it is proposed on the basis of present concepts regarding protein synthesis and RNA-virus replication, that the viral genome, insofar as it does not code for coat protein and for enzyme(s) required for replication of viral ribonucleic acid (RNA), may be "translated" into protein acting as the true cytopathic agent.Information on the nature of certain viral-cytopathogenic effects in hypersensitive and susceptible hosts, mainly as revealed by electron microscopy, is presented. The dramatic and fatal intracellular disorganization shown by hypersensitive hosts and suggestive of cytolytic processes invited a search for the presence and possible role of organelles containing hydrolytic enzymes (lysosomes). The in vitro detection of particle-bound acid phosphatase in different types of organelles, confirmed by electron microscopy, may explain at least some aspect of the observed cellular degeneration.

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