scholarly journals Isolate specific responses of the non-host grass Brachypodium distachyon to the fungal pathogen Zymoseptoria tritici, compared to wheat.

2020 ◽  
Author(s):  
Ailsing Reilly ◽  
Sujit Jung Karki ◽  
Anthony Twamley ◽  
Anna M.M Tiley ◽  
Steven Kildea ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Plant Immunity ◽  
Brachypodium Distachyon ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Pr Genes ◽  
Zymoseptoria Tritici ◽  
Expression Of Genes ◽  
Pathogenesis Related ◽  
Defence Gene Expression

Septoria tritici blotch (STB) is an important foliar disease of wheat that is caused by the fungal pathogen Zymoseptoria tritici. The grass Brachypodium distachyon has been used previously as a model system for cereal-pathogen interactions. In this study, we examined the non-host resistance (NHR) response of B. distachyon to two different Z. tritici isolates in comparison to wheat. These isolates vary in aggressiveness on wheat cv. Remus displaying significant differences in disease and pycnidia coverage. Using microscopy, we found that similar isolate specific responses were observed for H2O2 accumulation and cell death in both wheat and B. distachyon. Despite this, induction of isolate specific patterns of defence gene expression by Z. tritici did differ between B. distachyon and wheat. Our results suggest that phenylalanine ammonia lyase (PAL) expression may be important for NHR in B. distachyon while pathogenesis-related (PR) genes and expression of genes regulating reactive oxygen species (ROS) may be important to limit disease in wheat. Future studies of the B. distachyon-Z. tritici interaction may allow identification of conserved plant immunity targets which are responsible for the isolate specific responses observed in both plant species.

scholarly journals Differential dynamics of microbial community networks help identify microorganisms interacting with residue-borne pathogens: the case of Zymoseptoria tritici in wheat

2019 ◽  
Author(s):  
Lydie Kerdraon ◽  
Matthieu Barret ◽  
Valérie Laval ◽  
Frédéric Suffert
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Fungal Pathogen ◽  
Crop Residues ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Essential Information ◽  
Linear Discriminant ◽  
Network Analyses

AbstractBackgroundWheat residues are a crucial determinant of the epidemiology of Septoria tritici blotch, as they support the sexual reproduction of the causal agent Zymoseptoria tritici. We aimed to characterize the effect of infection with this fungal pathogen on the microbial communities present on wheat residues, and to identify microorganisms interacting with it. We used metabarcoding to characterize the microbiome associated with wheat residues placed outdoors, with and without preliminary Z. tritici inoculation, comparing a first set of residues in contact with the soil and a second set without contact with the soil, on four sampling dates in two consecutive years.ResultsThe diversity of the tested conditions, leading to the establishment of different microbial communities according to the origins of the constitutive taxa (plant only, or plant and soil), highlighted the effect of Z. tritici on the wheat residue microbiome. Several microorganisms were affected by Z. tritici infection, even after the disappearance of the pathogen. Linear discriminant analyses and ecological network analyses were combined to describe the communities affected by infection. The number of fungi and bacteria promoted or inhibited by inoculation with Z. tritici decreased over time, and was smaller for residues in contact with the soil. The interactions between the pathogen and other microorganisms appeared to be mostly indirect, despite the strong position of the pathogen as a keystone taxon in networks. Direct interactions with other members of the communities mostly involved fungi, including other wheat pathogens. Our results provide essential information about the alterations to the microbial community in wheat residues induced by the mere presence of a fungal pathogen, and vice versa. Species already described as beneficial or biocontrol agents were found to be affected by pathogen inoculation.ConclusionsThe strategy developed here can be viewed as a proof-of-concept focusing on crop residues as a particularly rich ecological compartment, with a high diversity of fungal and bacterial taxa originating from both the plant and soil compartments, and for Z. tritici-wheat as a model pathosystem. By revealing putative antagonistic interactions, this study paves the way for improving the biological control of residue-borne diseases.

scholarly journals Evidence of Selection for Fungicide Resistance in Zymoseptoria tritici Populations on Wheat in Western Oregon

Plant Disease ◽  
2016 ◽  
Vol 100 (2) ◽  
pp. 483-489 ◽  
Author(s):  
Laura E. Hayes ◽  
Kathryn E. Sackett ◽  
Nicole P. Anderson ◽  
Michael D. Flowers ◽  
Christopher C. Mundt
Keyword(s):  
Fungicide Resistance ◽  
Fungal Pathogen ◽  
Plant Pathogens ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Resistance Evolution ◽  
Regional Control ◽  
Selection For ◽  
Moderately Resistant

Plant pathogens pose a major challenge to maintaining food security in many parts of the world. Where major plant pathogens are fungal, fungicide resistance can often thwart regional control efforts. Zymoseptoria tritici, causal agent of Septoria tritici blotch, is a major fungal pathogen of wheat that has evolved resistance to chemical control products in four fungicide classes in Europe. Compared with Europe, however, fungicide use has been less and studies of fungicide resistance have been infrequent in North American Z. tritici populations. Here, we confirm first reports of Z. tritici fungicide resistance evolution in western Oregon through analysis of the effects of spray applications of propiconazole and an azoxystrobin + propiconazole mixture during a single growing season. Frequencies of strobilurin-resistant isolates, quantified as proportions of G143A mutants, were significantly higher in azoxystrobin-sprayed plots compared with plots with no azoxystrobin treatment at two different locations and were significantly higher in plots of a moderately resistant cultivar than in plots of a susceptible cultivar. Thus, it appears that western Oregon Z. tritici populations have the potential to evolve levels of strobilurin resistance similar to those observed in Europe. Although the concentration of propiconazole required to reduce pathogen growth by 50% values were numerically greater for isolates collected from plots receiving propiconazole than in control plots, this effect was not significant (P > 0.05).

scholarly journals Three LysM effectors of Zymoseptoria tritici collectively disarm chitin-triggered plant immunity

2020 ◽  
Author(s):  
Hui Tian ◽  
Craig I. MacKenzie ◽  
Luis Rodriguez-Moreno ◽  
Grardy C.M. van den Berg ◽  
Hongxin Chen ◽  
...  
Keyword(s):  
Plant Immunity ◽  
Effector Proteins ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Plant Host ◽  
Fungal Cell ◽  
Molecular Pattern ◽  
Fungal Hyphae ◽  
Ros Burst

SUMMARYChitin is a major structural component of fungal cell walls and acts as a microbe-associated molecular pattern (MAMP) that, upon recognition by a plant host, triggers the activation of immune responses. In order to avoid the activation of these responses, the Septoria tritici blotch (STB) pathogen of wheat, Zymoseptoria tritici, secretes LysM effector proteins. Previously, the LysM effectors Mg1LysM and Mg3LysM were shown to protect fungal hyphae against host chitinases. Furthermore, Mg3LysM, but not Mg1LysM, was shown to suppress chitin-induced reactive oxygen species (ROS) production. Whereas initially a third LysM effector gene was disregarded as a presumed pseudogene, we now provide functional data to show that also this gene encodes a LysM effector, named Mgx1LysM, that is functional during wheat colonization. While Mg3LysM confers a major contribution to Z. tritici virulence, Mgx1LysM and Mg1LysM contribute to Z. tritici virulence with smaller effects. All three LysM effectors display partial functional redundancy. We furthermore demonstrate that Mgx1LysM binds chitin, suppresses the chitin-induced ROS burst and is able to protect fungal hyphae against chitinase hydrolysis. Finally, we demonstrate that Mgx1LysM is able to undergo chitin-induced polymerisation. Collectively, our data show that Zymoseptoria tritici utilizes three LysM effectors to disarm chitin-triggered wheat immunity.

scholarly journals A small secreted protein from Zymoseptoria tritici interacts with a wheat E3 ubiquitin ligase to promote disease

2020 ◽  
Author(s):  
Sujit Jung Karki ◽  
Aisling Reilly ◽  
Binbin Zhou ◽  
Maurizio Mascarello ◽  
James Burke ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
E3 Ubiquitin Ligase ◽  
Bimolecular Fluorescence Complementation ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Virus Induced Gene Silencing ◽  
In Planta ◽  
Zymoseptoria Tritici

Abstract Septoria tritici blotch (STB), caused by the ascomycete fungus Zymoseptoria tritici, is a major threat to wheat production worldwide. The Z. tritici genome encodes many small secreted proteins (ZtSSPs) that are likely to play a key role in the successful colonization of host tissues. However, few of these ZtSSPs have been functionally characterized for their role during infection. In this study, we identified and characterized a small, conserved cysteine-rich secreted effector from Z. tritici which has homologues in other plant pathogens in the Dothideomycetes. ZtSSP2 was expressed throughout Z. tritici infection in wheat, with the highest levels observed early during infection. A yeast two-hybrid assay revealed an interaction between ZtSSP2 and wheat E3 ubiquitin ligase (TaE3UBQ) in yeast, and this was further confirmed in planta using bimolecular fluorescence complementation and co-immunoprecipitation. Down-regulation of this wheat E3 ligase using virus-induced gene silencing increased the susceptibility of wheat to STB. Together, these results suggest that TaE3UBQ is likely to play a role in plant immunity to defend against Z. tritici.

scholarly journals The effect of fungicide dose rate and mixtures on Zymoseptoria tritici in two cultivars of autumn sown wheat

2015 ◽  
Vol 68 ◽  
pp. 420-427
Author(s):  
J.B. Drummond ◽  
R.A. Craigie ◽  
M. Braithwaite ◽  
A.T. Gillum ◽  
B.L. McCloy
Keyword(s):  
Fungal Pathogen ◽  
Growth Stage ◽  
Flag Leaf ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Fixed Rate ◽  
Disease Pressure ◽  
Succinate Dehydrogenase Inhibitor ◽  
Demethylation Inhibitor

In the 201213 and 201314 seasons septoria tritici blotch (STB) caused by the fungal pathogen Zymoseptoria tritici was poorly controlled in autumn sown wheat in Canterbury In 201415 a low disease pressure season three trials were conducted to define the protectant and curative properties of two applications of triazole demethylation inhibitor inhibitor (DMI) and succinate dehydrogenase inhibitor (SDHI) fungicides for the control of STB at growth stage 31 and 39 on two cultivars of autumn sown wheat The protectant activity of triazole and SDHI fungicides was more effective on the flag leaf than the curative activity on leaf two The addition of an SDHI to a 75 fixed rate of triazole was more effective at controlling STB infection than triazoles alone The addition of SDHI fungicides also significantly increased yield The highest mean yields were achieved with the addition of a third application at GS65

scholarly journals Comparative Transcriptomics Reveals How Wheat Responds to Infection by Zymoseptoria tritici

2018 ◽  
Vol 31 (4) ◽  
pp. 420-431 ◽  
Author(s):  
Xin Ma ◽  
Beat Keller ◽  
Bruce A. McDonald ◽  
Javier Palma-Guerrero ◽  
Thomas Wicker
Keyword(s):  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Pathogenesis Related ◽  
Genes Encoding ◽  
Asymptomatic Phase ◽  
Related Proteins ◽  
Late Stages ◽  
Multiple Pathogen ◽  
Important Disease

The fungus Zymoseptoria tritici causes septoria tritici blotch (STB) on wheat, an important disease globally and the most damaging wheat disease in Europe. Despite the global significance of STB, the molecular basis of wheat defense against Z. tritici is poorly understood. Here, we use a comparative transcriptomic study to investigate how wheat responds to infection by four distinct strains of Z. tritici. We examined the response of wheat across the entire infection cycle, identifying both shared responses to the four strains and strain-specific responses. We found that the early asymptomatic phase is characterized by strong upregulation of genes encoding receptor-like kinases and pathogenesis-related proteins, indicating the onset of a defense response. We also identified genes that were differentially expressed among the four fungal strains, including genes related to defense. Genes involved in senescence were induced during both the asymptomatic phase and at late stages of infection, suggesting manipulation of senescence processes by both the plant and the pathogen. Our findings illustrate the need, when identifying important genes affecting disease resistance in plants, to include multiple pathogen strains.

scholarly journals Characterisation of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici

2017 ◽  
Author(s):  
Graeme J. Kettles ◽  
Carlos Bayon ◽  
Caroline A. Sparks ◽  
Gail Canning ◽  
Kostya Kanyuka ◽  
...  
Keyword(s):  
Expression Pattern ◽  
Effector Proteins ◽  
Yeast Cells ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
List Type ◽  
Expression Systems ◽  
Zymoseptoria Tritici ◽  
Loop Region

Abstract-The fungus Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB) disease of wheat leaves. Z. tritici secretes many functionally uncharacterised effector proteins during infection. Here we characterised a secreted ribonuclease (Zt6) with an unusual biphasic expression pattern.-Transient expression systems were used to characterise Zt6, and mutants thereof, in both host and non-host plants. Cell-free protein expression systems monitored impact of Zt6 protein on functional ribosomes, and in vitro assays of cells treated with recombinant Zt6 determined toxicity against bacteria, yeasts and filamentous fungi.-We demonstrated that Zt6 is a functional ribonuclease and that phytotoxicity is dependent on both the presence of a 22-amino acid N-terminal “loop” region and its catalytic activity. Zt6 selectively cleaves both plant and animal rRNA species, and is toxic to wheat, tobacco, bacterial and yeast cells but not to Z. tritici itself.-Zt6 is the first Z. tritici effector demonstrated to have a likely dual functionality. The expression pattern of Zt6 and potent toxicity towards microorganisms suggests that whilst it may contribute to the execution of wheat cell death, it is also likely to have an important secondary function in antimicrobial competition and niche protection.

scholarly journals Prevalence of QoI resistance and mtDNA diversity in the Irish Zymoseptoria tritici population

2019 ◽  
Vol 58 (1) ◽  
pp. 27-33
Author(s):  
S. Kildea ◽  
D.E. Bucar ◽  
F. Hutton ◽  
S. de la Rosa ◽  
T.E. Welch ◽  
...  
Keyword(s):  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Entire Group ◽  
Zymoseptoria Tritici ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Strain Collection ◽  
Increased Sensitivity ◽  
Mtdna Diversity

Abstract The emergence and spread of Quinone outside Inhibitor (QoI) fungicide resistance in the Irish Zymoseptoria tritici population in the early 2000s had immediate impacts on the efficacy of the entire group of fungicides for the control of septoria tritici blotch. As a result, a dramatic reduction in the quantities applied to winter wheat occurred in the following seasons. Even in the absence of these fungicides, the frequency of the resistance allele, G143A in the pathogens mtDNA has remained exceptionally high (>97%), and as such, it can be anticipated that continued poor efficacy of current QoI fungicides will be observed. Amongst the isolates with G143A, differences in sensitivity to the QoI pyraclostrobin were observed in vitro. The addition of the alternative oxidase (AOX) inhibitor salicylhydroxamic acid increased sensitivity in these isolates, suggesting some continued impairment of respiration by the QoI fungicides, albeit weak. Interestingly, amongst those tested, the strains from a site with a high frequency of inserts in the MFS1 transporter gene known to enhance QoI efflux did not exhibit this increase in sensitivity. A total of 19 mtDNA haplotypes were detected amongst the 2017 strain collection. Phylogenetic analysis confirmed the suggestion of a common ancestry of all the haplotypes, even though three of the haplotypes contained at least one sensitive strain.

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

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.

Advances in breeding techniques for durable Septoria tritici blotch (STB) resistance in cereals

2021 ◽  
pp. 303-356
Author(s):  
Harsh Raman ◽  
Keyword(s):  
Quantitative Resistance ◽  
Durable Resistance ◽  
Genetic Resistance ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Winter Cereal ◽  
Cereal Breeding ◽  
Qualitative Resistance ◽  
Breeding Techniques

Septoria tritici blotch (STB), caused by the hemibiotrophic fungus Zymoseptoria tritici, is one of the most important foliar diseases of winter cereal crops. Recent advances are helping to understand the genetic basis and architecture of resistance to STB. To date, at least 22 genes for qualitative resistance and over 200 quantitative trait loci (QTL) for quantitative resistance have been identified in cereals. This knowledge is enabling cereal breeding programs to develop varieties with more durable resistance to STB. This chapter reviews recent research on genetic resistance loci and breeding strategies based on both conventional and biotechnology-based breeding approaches (molecular marker/genomic-assisted breeding, genetic transformation, and gene-editing) to achieve achieving durable resistance to STB infection and minimise grain yield losses.

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