The Algal Polysaccharide Ulvan Induces Resistance in Wheat Against Zymoseptoria tritici Without Major Alteration of Leaf Metabolome

This study aimed to examine the ability of ulvan, a water-soluble polysaccharide from the green seaweed Ulva fasciata, to provide protection and induce resistance in wheat against the hemibiotrophic fungus Zymoseptoria tritici. Matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) analysis indicated that ulvan is mainly composed of unsaturated monosaccharides (rhamnose, rhamnose-3-sulfate, and xylose) and numerous uronic acid residues. In the greenhouse, foliar application of ulvan at 10 mg.ml–1 2 days before fungal inoculation reduced disease severity and pycnidium density by 45 and 50%, respectively. Ulvan did not exhibit any direct antifungal activity toward Z. tritici, neither in vitro nor in planta. However, ulvan treatment significantly reduced substomatal colonization and pycnidium formation within the mesophyll of treated leaves. Molecular assays revealed that ulvan spraying elicits, but does not prime, the expression of genes involved in several wheat defense pathways, including pathogenesis-related proteins (β-1,3-endoglucanase and chitinase), reactive oxygen species metabolism (oxalate oxidase), and the octadecanoid pathway (lipoxygenase and allene oxide synthase), while no upregulation was recorded for gene markers of the phenylpropanoid pathway (phenylalanine ammonia-lyase and chalcone synthase). Interestingly, the quantification of 83 metabolites from major chemical families using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) in both non-infectious and infectious conditions showed no substantial changes in wheat metabolome upon ulvan treatment, suggesting a low metabolic cost associated with ulvan-induced resistance. Our findings provide evidence that ulvan confers protection and triggers defense mechanisms in wheat against Z. tritici without major modification of the plant physiology.

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A Laminarin-Based Formulation Protects Wheat Against Zymoseptoria tritici Via Direct Antifungal Activity and Elicitation of Host Defense-Related Genes

Plant Disease ◽

10.1094/pdis-08-21-1675-re ◽

2022 ◽

Author(s):

Marlon C. de Borba ◽

Aline Cristina Velho ◽

Mateus B. de Freitas ◽

Maxime Holvoet ◽

Alessandra Maia-Grondard ◽

...

Keyword(s):

Antifungal Activity ◽

Metabolic Cost ◽

Allene Oxide ◽

In Planta ◽

Zymoseptoria Tritici ◽

Oxidase Gene ◽

Induce Resistance ◽

Oxide Synthase ◽

Related Proteins

The present study aimed to evaluate the potential of the laminarin-based formulation Vacciplant® to protect and induce resistance in wheat against Zymoseptoria tritici, a major pathogen on this crop. Under greenhouse conditions, a single foliar spraying of the product two days before inoculation with Z. tritici reduced disease severity and pycnidium density by 42% and 45%, respectively. Vacciplant® exhibited a direct antifungal activity on Z. tritici conidial germination both in vitro and in planta. Moreover, it reduced in planta substomatal colonization as well as pycnidium formation on treated leaves. Molecular investigations revealed that Vacciplant® elicits but did not prime the expression of several wheat genes related to defense pathways, including phenylpropanoids (phenylalanine ammonia-lyase and chalcone synthase), octadecanoids (lipoxygenase and allene oxide synthase), and pathogenesis‐related proteins (β‐1,3‐endoglucanase and chitinase). By contrast, it did not modulate the expression of oxalate oxidase gene involved in the reactive oxygen species metabolism. UHPLC-MS analysis indicated limited changes in leaf metabolome after product application in both non-inoculated and inoculated conditions, suggesting a low metabolic cost associated with induction of plant resistance. This study provides evidence that the laminarin-based formulation confers protection to wheat against Z. tritici through direct antifungal activity and elicitation of plant defense-associated genes.

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Saccharin Provides Protection and Activates Defense Mechanisms in Wheat Against the Hemibiotrophic Pathogen Zymoseptoria tritici

Plant Disease ◽

10.1094/pdis-05-20-1106-re ◽

2020 ◽

Author(s):

Samara Mejr ◽

Maryline Magnin-Robert ◽

Beatrice Randoux ◽

Alina Ghinet ◽

Patrice Halama ◽

...

Keyword(s):

Defense Mechanisms ◽

Foliar Application ◽

Crop Protection ◽

Hyphal Growth ◽

In Planta ◽

Zymoseptoria Tritici ◽

Gene Encoding ◽

Challenge Inoculation ◽

Pathogenesis Related Protein

Plant resistance inducers are among the most promising alternatives to develop sustainable crop protection. Here, we examined the ability of saccharin, a metabolite derived from probenazole, to protect wheat against Zymoseptoria tritici, the most frequently occurring and damaging foliar pathogen on this crop. The experiments were performed in the greenhouse by treating seedlings of the wheat cv. Alixan with 15 mM saccharin two days before challenge inoculation with the Z. tritici pathogenic strain T02596. Foliar application of saccharin resulted in 77 % disease severity reduction when compared to non-treated control plants. In vitro and in planta assays showed that saccharin did not exhibit any direct antifungal effect, neither on spore germination, nor on hyphal growth. Molecular investigations from 2 to 7 days post-treatment (dpt) revealed that saccharin treatment up-regulates the expression of genes encoding for lipoxygenase (LOX) at all sampled time-points and pathogenesis-related protein 1 (PR1) at 7 dpt, in both non-infectious and infectious contexts, as well as peroxidase (POX2) in non-infectious conditions. However, saccharin did not induce significant change in the expression of PAL gene encoding for phenylalanine ammonia-lyase. Our findings report for the first time the potential of saccharin to confer protection in wheat against Z. tritici through an elicitation and priming of LOX and PR gene-related defense pathways. Further investigations would provide a better deciphering of defense mechanisms activated by this molecule in wheat against Z. tritici.

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A Microbial Fermentation Mixture Reduces Fusarium Head Blight and Promotes Grain Weight but does not impact Septoria tritici blotch

European Journal of Plant Pathology ◽

10.1007/s10658-021-02396-4 ◽

2021 ◽

Author(s):

Tony Twamley ◽

Mark Gaffney ◽

Angela Feechan

Keyword(s):

Fusarium Head Blight ◽

Fungal Pathogens ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Microbial Fermentation ◽

In Planta ◽

Head Blight ◽

Zymoseptoria Tritici ◽

The Impact

AbstractFusarium graminearum and Zymoseptoria tritici cause economically important diseases of wheat. F. graminearum is one of the primary causal agents of Fusarium head blight (FHB) and Z. tritici is the causal agent of Septoria tritici blotch (STB). Alternative control methods are required in the face of fungicide resistance and EU legislation which seek to cut pesticide use by 2030. Both fungal pathogens have been described as either hemibiotrophs or necrotrophs. A microbial fermentation-based product (MFP) was previously demonstrated to control the biotrophic pathogen powdery mildew, on wheat. Here we investigated if MFP would be effective against the non-biotrophic fungal pathogens of wheat, F. graminearum and Z. tritici. We assessed the impact of MFP on fungal growth, disease control and also evaluated the individual constituent parts of MFP. Antifungal activity towards both pathogens was found in vitro but MFP only significantly decreased disease symptoms of FHB in planta. In addition, MFP was found to improve the grain number and weight, of uninfected and F. graminearum infected wheat heads.

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Analysis of small RNA silencing in Zymoseptoria tritici – wheat interactions

10.1101/501650 ◽

2018 ◽

Cited By ~ 2

Author(s):

Graeme J. Kettles ◽

Bernhard J. Hofinger ◽

Pingsha Hu ◽

Carlos Bayon ◽

Jason J. Rudd ◽

...

Keyword(s):

Small Rna ◽

Rna Virus ◽

Control Measure ◽

Pathogenic Fungi ◽

Fungal Colonization ◽

In Planta ◽

Zymoseptoria Tritici ◽

Mrna Targets ◽

Fungal Genes

AbstractCross-kingdom small RNA (sRNA) silencing has recently emerged as a mechanism facilitating fungal colonization and disease development. Here we characterized RNAi pathways in Zymoseptoria tritici, a major fungal pathogen of wheat, and assessed their contribution to pathogenesis. Computational analysis of fungal sRNA and host mRNA sequencing datasets was used to define the global sRNA populations in Z. tritici and predict their mRNA targets in wheat. 389 in planta-induced sRNA loci were identified. sRNAs generated from some of these loci were predicted to target wheat mRNAs including those potentially involved in pathogen defense. However, molecular approaches failed to validate targeting of selected wheat mRNAs by fungal sRNAs. Mutant strains of Z. tritici carrying deletions of genes encoding key components of RNAi such as Dicer-like (DCL) and Argounate (AGO) proteins were generated, and virulence bioassays suggested that these are dispensable for full infection of wheat. Nonetheless, our results did suggest the existence of non-canonical DCL-independent pathway(s) for sRNA biogenesis in Z. tritici. dsRNA targeting essential fungal genes applied in vitro or generated from an RNA virus vector in planta in a procedure known as HIGS (Host-Induced Gene Silencing) was ineffective in preventing Z. tritici growth or disease. We also demonstrated that Z. tritici is incapable of dsRNA uptake. Collectively, our data suggest that RNAi approaches for gene function analyses in this fungal species and potentially also as a control measure may not be as effective as has been demonstrated for some other plant pathogenic fungi.

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Small RNA bidirectional crosstalk during the interaction between wheat andZymoseptoria tritici

10.1101/501593 ◽

2018 ◽

Cited By ~ 4

Author(s):

Xin Ma ◽

Nicolas Bologna ◽

Javier Palma-Guerrero

Keyword(s):

Fungal Infection ◽

Target Genes ◽

In Planta ◽

Zymoseptoria Tritici ◽

Plant Infection ◽

Gene Transcripts ◽

Plant Pathogen Interactions ◽

Lower Expression

AbstractCross-kingdom RNAi has been shown to play important roles during plant pathogen interactions. But this cross-kingdom RNAi was still unexplored in the wheat-Zymoseptoria triticipathosystem. Here we performed a detailed analysis of the sRNA bidirectional crosstalk between wheat andZ.tritici. Using a combination of sRNA-seq and mRNA-seq we were able to identify known and novel sRNAs and study their expression and their action on putative targets in both wheat andZ.tritici. We predicted the target genes of all the sRNAs in either wheat orZ.triticitranscriptome and used degradome analysis to validate the cleavage of these gene transcripts. We could not find any clear evidence of a cross-kingdom RNAi in this pathosystem. We also found that the fungal sRNA enrichment was lowerin plantathan duringin vitrogrowth, probably due to the lower expression of the only Dicer gene of the fungus during plant infection. However, we found a downregulation of specific wheat sRNAs during the fungal infection, leading to a boost expression of wheat defense related genes, which may be enhancing the plant defense ability against the pathogen. Additionally, the fungal infection also induced sRNAs regulating the expression of specific wheat genes, including auxin related genes, as an immune response. These results confirm the role of sRNAs in the regulation of wheat defenses duringZ.triticiinfection. Our findings contribute to improve our understanding of the interactions between wheat andZ.tritici.

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In planta chromatin immunoprecipitation in Zymoseptoria tritici reveals chromatin-based regulation of putative effector gene expression

10.1101/544627 ◽

2019 ◽

Cited By ~ 4

Author(s):

Jessica L. Soyer ◽

Jonathan Grandaubert ◽

Janine Haueisen ◽

Klaas Schotanus ◽

Eva H. Stukenbrock

Keyword(s):

Gene Expression ◽

Histone Modifications ◽

Chromatin Immunoprecipitation ◽

High Throughput Sequencing ◽

Histone H3 ◽

In Planta ◽

Zymoseptoria Tritici ◽

Effector Gene ◽

Effector Genes

SummaryDuring infection, pathogens secrete effectors, key elements of pathogenesis. In several phytopathogenic fungi, synchronous waves of effector genes are expressed during plant infection to manipulate and silence plant defenses. In Zymoseptoria tritici, causing septoria leaf blotch of wheat, at least two waves of effector genes are expressed, during the asymptomatic phase and at the switch to necrotrophy. The underlying factors responsible for the fine-tuned regulation of effector gene expression in this pathogen are unknown. Previously, a detailed map of the chromatin structure in vitro of Z. tritici was generated by chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) targeting histone modifications typical for euchromatin (di-methylation of the lysine 4 of the histone H3, H3K4me2) or heterochromatin (tri-methylation of the lysine 9 and 27 of the histone H3, H3K9me3 and H3K27me3). Based on the hypothesis that changes in the histone modifications contribute to the transcriptional control of pathogenicity-related genes, we tested whether different sets of genes are associated with different histone modifications in vitro. We correlated the in vitro histone maps with in planta transcriptome data and show that genes located in heterochromatic domains in vitro are highly up-regulated at the switch toward necrotrophy. We combined our integrated analyses of genomic, transcriptomic and epigenomic data with ChIP-qPCR in planta and thereby provide further evidence for the involvement of histone modifications in the transcriptional dynamic of putative pathogenicity-related genes of Z. tritici.

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Plant Biostimulants: New Insights Into the Biological Control of Verticillium Wilt of Olive

Frontiers in Plant Science ◽

10.3389/fpls.2021.662178 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ana López-Moral ◽

Carlos Agustí-Brisach ◽

Antonio Trapero

Keyword(s):

Biological Control ◽

Verticillium Wilt ◽

Mycelial Growth ◽

Foliar Application ◽

Control Measures ◽

The Other ◽

Limiting Factor ◽

In Planta ◽

Disease Reduction

Verticillium wilt of olive (Olea europaea subsp. europaea L.) (VWO), caused by the hemibiotrophic soil-borne fungus Verticillium dahliae Kleb., is considered the major limiting factor of this crop in Mediterranean-type climate regions of the world. The absence of effective chemical treatments makes the control of the disease difficult. In this way, the use of biostimulants and host plant defense inducers seems to be one of the most promising biological and eco-friendly alternatives to traditional control measures. Thus, the main goal of this study was to evaluate the effect of 32 products, including amino acids, micronutrients, microorganisms, substances of natural origin, copper complex-based products, and organic and inorganic salts against the disease under controlled conditions. To this end, their effects on mycelial growth and microsclerotia (MS) inhibition of V. dahliae were evaluated by means of dual cultures or by sensitivity tests in vitro as well as on disease progression in planta. Wide ranging responses to the pathogen and disease reduction levels were observed among all the products tested, suggesting multiple modes of action. Copper-based products were among the most effective for mycelial growth and MS inhibition, whereas they did not show an important effect on the reduction of disease severity in planta. Phoma sp. and Aureobasidium pullulans were the most effective in disease reduction in planta with foliar application. On the other hand, two phosphite salts, one with copper and the other with potassium, were the most effective in disease reduction in planta when they were applied by irrigation, followed by A. pullulans and Bacillus amyloliquefaciens. This study will be useful to select the best candidates for future studies, contributing significantly to new insights into the current challenge of the biological control of VWO.

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Extracellular vesicles from the apoplastic fungal wheat pathogen Zymoseptoria tritici

10.21203/rs.3.rs-40104/v2 ◽

2020 ◽

Author(s):

Erin H Hill ◽

Peter Solomon

Keyword(s):

Extracellular Vesicles ◽

Fungal Pathogen ◽

Plant Pathogens ◽

Sequence Similarity ◽

Protein Composition ◽

Broth Culture ◽

In Planta ◽

Zymoseptoria Tritici ◽

Culture Filtrates

Abstract Background: The fungal pathogen Zymoseptoria tritici is a significant constraint to wheat production in temperate cropping regions around the world. Despite its agronomic impacts, the mechanisms allowing the pathogen to asymptomatically invade and grow in the apoplast of wheat leaves before causing extensive host cell death remain elusive. Given recent evidence of extracellular vesicles (EVs) – secreted, membrane-bound nanoparticles containing molecular cargo – being implicated in extracellular communication between plants and fungal pathogen, we have initiated an in vitro investigation of EVs from this apoplastic fungal wheat pathogen. We aimed to isolate EVs from Z. tritici broth cultures and examine their protein composition in relation to the soluble protein in the culture filtrate and to existing fungal EV proteomes.Results: Zymoseptoria tritici EVs were isolated from broth culture filtrates using differential ultracentrifugation (DUC) and examined with transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Z. tritici EVs were observed as a heterogeneous population of particles, with most between 50 – 250 nm. These particles were found in abundance in the culture filtrates of viable Z. tritici cultures, but not heat-killed cultures incubated for an equivalent time and of comparable biomass. Bottom-up proteomic analysis using LC-MS/MS, followed by stringent filtering revealed 240 Z. tritici EV proteins. These proteins were distinct from soluble proteins identified in Z. tritici culture filtrates, but were similar to proteins identified in EVs from other fungi, based on sequence similarity analyses. Notably, a putative marker protein recently identified in Candida albicans EVs was also consistently detected in Z. tritici EVs.Conclusion: We have shown EVs can be isolated from the devastating fungal wheat pathogen Z. tritici and are similar to protein composition to previously characterised fungal EVs. EVs from human pathogenic fungi are implicated in virulence, but the role of EVs in the interaction of phytopathogenic fungi and their hosts is unknown. These in vitro analyses provide a basis for expanding investigations of Z. tritici EVs in planta, to examine their involvement in the infection process of this apoplastic wheat pathogen and more broadly, advance understanding of noncanonical secretion in filamentous plant pathogens.

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Importance of the C12 Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against Zymoseptoria tritici

Molecules ◽

10.3390/molecules26010040 ◽

2020 ◽

Vol 26 (1) ◽

pp. 40

Author(s):

Rémi Platel ◽

Ludovic Chaveriat ◽

Sarah Le Guenic ◽

Rutger Pipeleers ◽

Maryline Magnin-Robert ◽

...

Keyword(s):

Plasma Membranes ◽

Biological Activities ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Multi Drug Resistance ◽

Activity Levels ◽

In Planta ◽

Zymoseptoria Tritici ◽

Relationship Analysis

The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. tritici cells. The efficacy of the most active compound Rh-Est-C12 was 20-fold lower in planta than in vitro; an optimization of the formulation is thus required to increase its effectiveness. No Z. tritici strain-dependent activity was scored for Rh-Est-C12 that exhibited similar antifungal activity levels towards strains differing in their resistance patterns to demethylation inhibitor fungicides, including multi-drug resistance strains. This study reports new insights into the use of bio-inspired RLs to control Z. tritici.

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Extraordinary genome instability and widespread chromosome rearrangements during vegetative growth

10.1101/304915 ◽

2018 ◽

Cited By ~ 4

Author(s):

Mareike Möller ◽

Michael Habig ◽

Michael Freitag ◽

Eva H. Stukenbrock

Keyword(s):

Incubation Temperature ◽

Genome Instability ◽

Pathogenic Fungus ◽

Chromosome Instability ◽

Chromosome Breakage ◽

Chromosome Loss ◽

In Planta ◽

Zymoseptoria Tritici ◽

Accessory Chromosomes

AbstractThe haploid genome of the pathogenic fungusZymoseptoria triticiis contained on “core” and “accessory” chromosomes. While 13 core chromosomes are found in all strains, as many as eight accessory chromosomes show presence/absence variation and rearrangements among field isolates. We investigated chromosome stability using experimental evolution, karyotyping and genome sequencing. We report extremely high and variable rates of accessory chromosome loss during mitotic propagationin vitroandin planta. Spontaneous chromosome loss was observed in 2 to >50 % of cells during four weeks of incubation. Similar rates of chromosome loss in the closely relatedZ. ardabiliaesuggest that this extreme chromosome dynamic is a conserved phenomenon in the genus. Elevating the incubation temperature greatly increases instability of accessory and even core chromosomes, causing severe rearrangements involving telomere fusion and chromosome breakage. Chromosome losses do not impact the fitness ofZ. tritici in vitro, but some lead to increased virulence suggesting an adaptive role of this extraordinary chromosome instability.

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