Survival of the fittest: How the rice microbial community forces Sarocladium oryzae into pathogenicity

2020 ◽  
Author(s):  
K J Peeters ◽  
K Audenaert ◽  
M Höfte
Keyword(s):  
Null Model ◽  
Toxin Production ◽  
Pairwise Interactions ◽  
Helvolic Acid ◽  
Community Forces ◽  
Survival Of The Fittest ◽  
Endophyte Community ◽  
Rice Endophytes ◽  
Sheath Rot

ABSTRACT The fungus Sarocladium oryzae (Sawada) causes rice sheath rot and produces the phytotoxins cerulenin and helvolic acid. Both toxins show antimicrobial activity but only helvolic acid production in the rice sheath correlates with virulence. S. oryzae isolates that differ in their toxin production were used to study their interaction with the rice culturable bacterial endophyte community. The diversity and community structure was defined in the edge of sheath rot lesions, followed by a null model-based co-occurrence analysis to discover pairwise interactions. Non-random pairs were co-cultured to study the nature of the interactions and the role of the toxins herein. Compared to healthy sheaths, endophyte diversity strongly increased when infected with the least virulent S. oryzae isolates producing low amounts of toxins. Virulent S. oryzae isolates did not affect diversity but caused strong shifts in species composition. The endophyte community of healthy rice plants was dominated by B. cereus. This bacterium was enriched in lesions produced by low-virulent S. oryzae isolates and caused hyphal lysis. Contrarily, helvolic acid producers eliminated this bacterium from the sheath endosphere. We conclude that S. oryzae needs to produce antibiotics to defend itself against antagonistic rice endophytes to successfully colonize and infect the rice sheath.

scholarly journals Auxin, abscisic acid and jasmonate are the central players in rice sheath rot caused by Sarocladium oryzae and Pseudomonas fuscovaginae

2020 ◽  
Author(s):  
Kaat Peeters ◽  
Maarten Ameye ◽  
Kristof Demeestere ◽  
Kris Audenaert ◽  
Monica Hofte
Keyword(s):  
Abscisic Acid ◽  
Host Response ◽  
Wild Type ◽  
Yield Parameters ◽  
Mutant Strains ◽  
Rice Disease ◽  
Membrane Bound ◽  
Helvolic Acid ◽  
Sheath Rot

Abstract Sheath rot is an emerging rice disease that causes severe yield losses worldwide. The main causal agents are the toxin producers Sarocladium oryzae and Pseudomonas fuscovaginae. The fungus S. oryzae produces helvolic acid and cerulenin and the bacterium P. fuscovaginae produces cyclic lipopeptides. Helvolic acid and the lipopeptide, fuscopeptin, inhibit membrane-bound H+-ATPase pumps in the rice plant. To manage rice sheath rot, a better understanding of the host response and virulence strategies of the pathogens is required. This study investigated the interaction of the sheath rot pathogens with their host and the role of their toxins herein. Japonica rice was inoculated with high- and low-helvolic acid-producing S. oryzae isolates or with P. fuscovaginae wild type and fuscopeptin mutant strains. During infection, cerulenin, helvolic acid and the phytohormones abscisic acid, jasmonate, auxin and salicylic acid were quantified in the sheath. In addition, disease severity and grain yield parameters were assessed. Rice plants responded to high-toxin-producing S. oryzae and P. fuscovaginae strains with an increase in abscisic acid, jasmonate and auxin levels. We conclude that, for both pathogens, toxins play a core role during sheath rot infection. S. oryzae and P. fuscovaginae interact with their host in a similar way. This may explain why both sheath rot pathogens cause very similar symptoms despite their different nature.

scholarly journals Morphological, Pathogenic and Toxigenic Variability in the Rice Sheath Rot Pathogen Sarocladium Oryzae

Toxins ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 109 ◽  
Author(s):  
Kaat José Peeters ◽  
Ashley Haeck ◽  
Lies Harinck ◽  
Oluwatoyin Oluwakemi Afolabi ◽  
Kristof Demeestere ◽  
...  
Keyword(s):  
Acid Production ◽  
High Resolution Mass Spectrometry ◽  
Toxin Production ◽  
Mass Spectrometry Analysis ◽  
In Planta ◽  
Spectrometry Analysis ◽  
Helvolic Acid ◽  
Phylogenetic Lineages ◽  
Sheath Rot

Sheath rot is an emerging rice disease that leads to considerable yield losses. The main causal agent is the fungus Sarocladium oryzae. This pathogen is known to produce the toxins cerulenin and helvolic acid, but their role in pathogenicity has not been clearly established. S. oryzea isolates from different rice-producing regions can be grouped into three phylogenetic lineages. When grown in vitro, isolates from these lineages differed in growth rate, colour and in the ability to form sectors. A diverse selection of isolates from Rwanda and Nigeria, representing these lineages, were used to further study their pathogenicity and toxin production. Liquid chromatography high-resolution mass spectrometry analysis was used to measure cerulenin and helvolic acid production in vitro and in planta. The three lineages clearly differed in pathogenicity on the japonica cultivar Kitaake. Isolates from the least pathogenic lineage produced the highest levels of cerulenin in vitro. Helvolic acid production was not correlated with the lineage. Sectorisation was observed in isolates from the two least pathogenic lineages and resulted in a loss of helvolic acid production. In planta, only the production of helvolic acid, but not of cerulenin, correlated strongly with disease severity. The most pathogenic isolates all belonged to one lineage. They were phenotypically stable, shown by the lack of sectorisation, and therefore maintained high helvolic acid production in planta.

scholarly journals Auxin, Abscisic Acid and Jasmonate Are the Central Players in Rice Sheath Rot Caused by Sarocladium oryzae and Pseudomonas fuscovaginae

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
K. J. Peeters ◽  
M. Ameye ◽  
K. Demeestere ◽  
K. Audenaert ◽  
M. Höfte
Keyword(s):  
Abscisic Acid ◽  
Host Response ◽  
Wild Type ◽  
Yield Parameters ◽  
Mutant Strains ◽  
Rice Disease ◽  
Membrane Bound ◽  
Helvolic Acid ◽  
Sheath Rot

AbstractSheath rot is an emerging rice disease that causes severe yield losses worldwide. The main causal agents are the toxin producers Sarocladium oryzae and Pseudomonas fuscovaginae. The fungus S. oryzae produces helvolic acid and cerulenin and the bacterium P. fuscovaginae produces cyclic lipopeptides. Helvolic acid and the lipopeptide, fuscopeptin, inhibit membrane-bound H+-ATPase pumps in the rice plant. To manage rice sheath rot, a better understanding of the host response and virulence strategies of the pathogens is required. This study investigated the interaction of the sheath rot pathogens with their host and the role of their toxins herein. Japonica rice was inoculated with high- and low-helvolic acid-producing S. oryzae isolates or with P. fuscovaginae wild type and fuscopeptin mutant strains. During infection, cerulenin, helvolic acid and the phytohormones abscisic acid, jasmonate, auxin and salicylic acid were quantified in the sheath. In addition, disease severity and grain yield parameters were assessed. Rice plants responded to high-toxin-producing S. oryzae and P. fuscovaginae strains with an increase in abscisic acid, jasmonate and auxin levels. We conclude that, for both pathogens, toxins play a core role during sheath rot infection. S. oryzae and P. fuscovaginae interact with their host in a similar way. This may explain why both sheath rot pathogens cause very similar symptoms despite their different nature.

scholarly journals In a Neotropical Periurban Park, Fruit Consumption by Birds Seems to Be a Random Process

2021 ◽  
Vol 9 ◽  
Author(s):  
Issaac Azrrael Teodosio-Faustino ◽  
Edgar Chávez-González ◽  
Ernesto Ruelas Inzunza
Keyword(s):  
Random Process ◽  
Probabilistic Models ◽  
Null Model ◽  
Interaction Network ◽  
Chromatic Contrast ◽  
Fruit Consumption ◽  
Pairwise Interactions ◽  
Multiple Variable ◽  
Achromatic Contrast

Frugivory interactions between birds and fruit-bearing plants are shaped by the abundance of its interacting species, their temporal overlap, the matching of their morphologies, as well as fruit and seed characteristics. Our study evaluates the role of seven factors of fruits and plants in determining the frequency of whole-fruit consumption by birds. We studied the frugivory network of a Neotropical periurban park in Xalapa, Veracruz, Mexico, and quantified relative abundance and phenology of birds and fruit, as well as fruit morphology, chromatic and achromatic contrast, and nutritional content. Using a maximum likelihood approach, we compared the observed interaction network with 62 single- and multiple-variable probabilistic models. Our network is composed of 11 plants and 17 birds involved in 81 frugivory interactions. This network is nested, modular, and relatively specialized. However, the frequency of pairwise interactions is not explained by the variables examined in our probabilistic models and found the null model has the best performance. This indicates that no single predictor or combination of them is better at explaining the observed frequency of pairwise interactions than the null model. The subsequent four top-ranking models, with ΔAIC values < 100, are single-variable ones: carbohydrate content, lipid content, chromatic contrast, and morphology. Two- and three-variable models show the poorest fit to observed data. The lack of a deterministic pattern does not support any of our predictions nor neutral- or niche-based processes shaping the observed pattern of fruit consumption in our interaction network. It may also mean that fruit consumption by birds in this periurban park is a random process. Although our study failed to find a pattern, our work exemplifies how investigations done in urban settings, poor in species and interactions, can help us understand the role of disturbance in the organization of frugivory networks and the processes governing their structure.

scholarly journals Auxin, abscisic acid and jasmonate are the central players in rice sheath rot caused by Sarocladium oryzae and Pseudomonas fuscovaginae

2020 ◽  
Author(s):  
Kaat Peeters ◽  
Maarten Ameye ◽  
Kristof Demeestere ◽  
Kris Audenaert ◽  
Monica Hofte
Keyword(s):  
Abscisic Acid ◽  
Host Response ◽  
Wild Type ◽  
Yield Parameters ◽  
Mutant Strains ◽  
Rice Disease ◽  
Membrane Bound ◽  
Helvolic Acid ◽  
Sheath Rot

Abstract Sheath rot is an emerging rice disease that causes severe yield losses worldwide. The main causal agents are the toxin producers Sarocladium oryzae and Pseudomonas fuscovaginae. The fungus S. oryzae produces helvolic acid and cerulenin and the bacterium P. fuscovaginae produces cyclic lipopeptides. Helvolic acid and the lipopeptide, fuscopeptin, inhibit membrane-bound H+-ATPase pumps in the rice plant. To manage rice sheath rot, a better understanding of the host response and virulence strategies of the pathogens is required. This study investigated the interaction of the sheath rot pathogens with their host and the role of their toxins herein. Japonica rice was inoculated with high- and low-helvolic acid-producing S. oryzae isolates or with P. fuscovaginae wild type and fuscopeptin mutant strains. During infection, cerulenin, helvolic acid and the phytohormones abscisic acid, jasmonate, auxin and salicylic acid were quantified in the sheath. In addition, disease severity and grain yield parameters were assessed. Rice plants responded to high-toxin-producing S. oryzae and P. fuscovaginae strains with an increase in abscisic acid, jasmonate and auxin levels. We conclude that, for both pathogens, toxins play a core role during sheath rot infection. S. oryzae and P. fuscovaginae interact with their host in a similar way. This may explain why both sheath rot pathogens cause very similar symptoms despite their different nature.

scholarly journals Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Babita Adhikari Dhungel ◽  
Revathi Govind
Keyword(s):  
Diarrheal Disease ◽  
Toxin Production ◽  
The United States ◽  
Upstream Region ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Master Regulator ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

From great man to fittest survivor: Reputation, recapitulation and survival in Victorian concepts of Wagner's genius

2009 ◽  
Vol 13 (2_suppl) ◽  
pp. 415-445
Author(s):  
Bennett Zon
Keyword(s):  
Richard Wagner ◽  
Victorian Culture ◽  
Modern Music ◽  
Scientific Terminology ◽  
The Arts ◽  
Victorian Period ◽  
Musical History ◽  
Survival Of The Fittest

The transposition of the Great Man into the Fittest Survivor is at the very root of an endemic interchange between the sciences and the arts in late Victorian culture, giving rich metaphoric substance to more heavily concretised scientific terminology. Herbert Spencer's famous phrase, “survival of the fittest” is, arguably, one of the most commonly transposed and consequently influential scientific expressions of the Victorian period, and as such, one of its most malleable idioms. In Victorian musicology this influence is especially obvious in biographical works which privilege Richard Wagner as the greatest genius of musical history. Thus in Mezzotints in Modern Music (1899) James Huneker declares that “Wagner carried within his breast the precious eucharist of genius. ” It is the attitude of Huneker and like-minded musicologists, like C. Hubert H. Parry, William Wallace, Francis Hueffer and Richard Wallaschek, which forms the basis of a three-part exploration of Wagner's genius, covering (1) the role of “endurance” in Victorian definitions of genius, from Carlyle and Sully to Galton; (2) the influence of German morphology on evolutionary terminology in Britain, with particular reference to ontogeny, phylogeny and recapitulation; and (3) Spencer's adaptation of German morphology and his influence on Victorian perceptions of Wagner's genius. These collectively argue through the paradigm of Wagner that the formulation of late Victorian musical genius was incomplete without recourse to evolutionary terminology of survival. Indeed, for Victorian musicology, Wagner, the Great Man, had evolved Into Wagner, the Fittest Survivor.

scholarly journals Cyclic Diguanylate Regulates Virulence Factor Genes via Multiple Riboswitches inClostridium difficile

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Robert W. McKee ◽  
Carissa K. Harvest ◽  
Rita Tamayo
Keyword(s):  
Gene Expression ◽  
Clostridium Difficile ◽  
Biofilm Formation ◽  
Toxin Production ◽  
Intestinal Colonization ◽  
Cyclic Diguanylate ◽  
Signaling Molecule ◽  
Content Type ◽  
Surface Motility

ABSTRACTThe intracellular signaling molecule cyclic diguanylate (c-di-GMP) regulates many processes in bacteria, with a central role in controlling the switch between motile and nonmotile lifestyles. Recent work has shown that inClostridium difficile(also calledClostridioides difficile), c-di-GMP regulates swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we determined the transcriptional regulon of c-di-GMP inC. difficile,employing overexpression of a diguanylate cyclase gene to artificially manipulate intracellular c-di-GMP. Consistent with prior work, c-di-GMP regulated the expression of genes involved in swimming and surface motility. c-di-GMP also affected the expression of multiple genes encoding cell envelope proteins, several of which affected biofilm formationin vitro. A substantial proportion of the c-di-GMP regulon appears to be controlled either directly or indirectly via riboswitches. We confirmed the functionality of 11 c-di-GMP riboswitches, demonstrating their effects on downstream gene expression independent of the upstream promoters. The class I riboswitches uniformly functioned as “off” switches in response to c-di-GMP, while class II riboswitches acted as “on” switches. Transcriptional analyses of genes 3′ of c-di-GMP riboswitches over a broad range of c-di-GMP levels showed that relatively modest changes in c-di-GMP levels are capable of altering gene transcription, with concomitant effects on microbial behavior. This work expands the known c-di-GMP signaling network inC. difficileand emphasizes the role of the riboswitches in controlling known and putative virulence factors inC. difficile.IMPORTANCEInClostridium difficile, the signaling molecule c-di-GMP regulates multiple processes affecting its ability to cause disease, including swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we used RNA-seq to define the transcriptional regulon of c-di-GMP inC. difficile. Many new targets of c-di-GMP regulation were identified, including multiple putative colonization factors. Transcriptional analyses revealed a prominent role for riboswitches in c-di-GMP signaling. Only a subset of the 16 previously predicted c-di-GMP riboswitches were functionalin vivoand displayed potential variability in their response kinetics to c-di-GMP. This work underscores the importance of studying c-di-GMP riboswitches in a relevant biological context and highlights the role of the riboswitches in controlling gene expression inC. difficile.

scholarly journals The role of Clt1-regulated-Xylan metabolism in the melanin and toxin formation for the pathogenicity of Curvularia lunata in Maize

2021 ◽  
Author(s):  
Jinxin Gao ◽  
Jie Chen
Keyword(s):  
Toxin Production ◽  
Bimolecular Fluorescence Complementation ◽  
Curvularia Lunata ◽  
Yeast Two Hybrid ◽  
Acetyl Xylan Esterase ◽  
Btb Domain ◽  
Intermediate Metabolites ◽  
Regulative Mechanism ◽  
Two Hybrid

We previously reported that the BTB domain-containing protein Clt1 regulates melanin and toxin synthesis, conidiation, and pathogenicity in Curvularia lunata, but the interacting proteins and regulative mechanism of Clt1 are unclear. In this research, we identified two proteins, which respectively correspond to xylanase (Clxyn24) and acetyl xylan esterase (Claxe43) from C. lunata were regulated by Clt1. Yeast two-hybrid (Y2H), and bimolecular fluorescence complementation assays were conducted to verify the interaction of Clt1 with full-length Clxyn24 and Claxe43. Furthermore, the Y2H assay revealed that Clt1 physically interacted with Clxyn24 and Claxe43 through its BTB domain to degrade xylan which was used as a carbon source for C. lunata growth. The utilization of xylan provides acetyl-CoA for the synthesis of melanin and toxin, as well as energy and other intermediate metabolites for conidiation. Furthermore, transcriptome analysis revealed that PKS18 and its 13 flanking genes are found clustered in a region spanning 57.89 kb on scaffold 9 of the C. lunata CX-3 genome were down-regulated in toxin production deficient mutant T806, and this cluster is possibly responsible for toxin biosynthesis of C. lunata.

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