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

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

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

10.1101/587667 ◽

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.

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

Plant Disease ◽

10.1094/pdis-02-15-0214-re ◽

2016 ◽

Vol 100 (2) ◽

pp. 483-489 ◽

Cited By ~ 22

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).

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

Phytopathology ◽

10.1094/phyto-02-20-0041-r ◽

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.

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Epidemiological factors of septoria tritici blotch (Zymoseptoria tritici) in durum wheat (Triticum turgidum) in the highlands of Wollo, Ethiopia

Ecological Processes ◽

10.1186/s13717-020-00258-1 ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Bogale Nigir Hailemariam ◽

Yosef Geberehawariat Kidane ◽

Amare Ayalew

Keyword(s):

Soil Type ◽

Growth Stage ◽

Planting Date ◽

Plant Population ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Zymoseptoria Tritici ◽

Weed Population ◽

Independent Variables ◽

Previous Crop

Abstract Background Septoria tritici blotch (STB) (Zymoseptoria tritici) is a major disease of durum wheat, an economic crop grown in the highlands of Wollo in Ethiopia. Methods To determine the status of this disease, we conducted surveys in five districts of Wollo (Meket, Woreilu, Wadila, Jama, and Dessie Zuria) during the 2015 cropping season. We visited 75 farm plots to determine the prevalence, incidence, and severity of STB. Results STB prevalence varied among locations, genotypes, planting dates, growth stages, previous crops, plant population, weed population, and soil types. Similarly, disease intensity also varied along all independent variables. The level of incidence was high in all the visited districts, and the level severity ranged from 9.9 to 59.3% while the incidence varied from 50 to 100%. The mean differences in incidence and severity within the districts’ variable classes, altitude, varieties, growth stage, plant population, planting date, previous crop, weed population, and soil type were high. The independent variables, districts, altitude, varieties, growth stage, plant population, planting date, previous crops, weed population, and soil type, were significantly associated with high incidence and severity of STB as single predictor in the logistic regression model. A reduced multiple variable model was fitted using districts, altitude, varieties, growth stage, plant population, planting date, previous crop, weed population, and soil type as independent variables. High incidence (> 50%) and severity (> 25%) had a high probability of association to all independent variables, except previous crop. Low disease incidence (≤ 50%) and low disease severity (≤ 25%) had high probability of association to the previous crop. Conclusion Environmental variables, cultivation practice, and responses were important for the development of STB. Therefore, these factors must be considered in designing strategies for the effective management of STB.

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First Report of Resistance to QoI Fungicides in North American Populations of Zymoseptoria tritici, Causal Agent of Septoria Tritici Blotch of Wheat

Plant Disease ◽

10.1094/pdis-05-13-0486-pdn ◽

2013 ◽

Vol 97 (11) ◽

pp. 1511-1511 ◽

Cited By ~ 17

Author(s):

L. K. Estep ◽

M. Zala ◽

N. P. Anderson ◽

K. E. Sackett ◽

M. Flowers ◽

...

Keyword(s):

De Novo ◽

Flag Leaf ◽

Causal Agent ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Cellular Respiration ◽

Zymoseptoria Tritici ◽

Science Field ◽

Qoi Fungicides ◽

Wheat Field

The G143A mutation in cytb (cytochrome b gene) is associated with high levels of resistance to quinone outside inhibitor (QoI or strobilurin) fungicides that disrupt electron transport during cellular respiration (1). The G143A mutation in Zymoseptoria tritici (synonyms: Mycosphaerella graminicola and Septoria tritici), the causal agent of septoria tritici blotch of wheat (Triticum aestivum), was first reported in Europe in 2001 (1). Although Z. tritici has a global distribution (3), G143A mutants of Z. tritici have not been reported outside of Europe. We used PCR-RFLP (4) to estimate the frequencies of G143A mutants in Z. tritici populations at two locations in the Willamette Valley of western Oregon: the Hyslop Crop Science Field Research Laboratory (Hyslop Farm, HF), Benton County (44°37′52.85″ N, 123°11′55.19″ W) and research plots planted in a commercial wheat field in Washington County (45°33′58.53″ N, 123°00′11.78″ W) (North Valley Farm, NVF). Isolates originated from flag leaf collections from two cultivars (‘Bobtail’ and ‘Tubbs 06’) made in April and June of 2012 from plants in a replicated fungicide-treatment experiment, with isolates collected from both sprayed and unsprayed plots. Sixteen of the 169 isolates (9.5%) from HF possessed the G143A mutation (7 of 132 isolates from plots not receiving a QoI fungicide and 9 of 37 isolates collected from plots receiving two applications of the QoI azoxystrobin). One hundred forty six of the 175 isolates (83.4%) from NVF were G143A mutants (101 of 129 isolates from plots receiving no QoI fungicide and 45 of 46 isolates from plots receiving two applications of azoxystrobin). Results of phenotypic assays of a subset of 10 isolates from each location (5 mutants, 5 wild types from each location; 20 isolates altogether) supported a high level of resistance to azoxystrobin only in the G143A mutants. All 10 G143A mutants developed colonies after 8 days of growth on YMA plates amended with SHAM (2) and 1 ppm or 10 ppm azoxystrobin, with nine and eight G143A mutant isolates developing colonies on plates amended with 1 ppm and 10 ppm azoxystrobin, respectively. None of the wild-type isolates developed colonies on plates amended with SHAM and 1 ppm azoxystrobin, nor on plates amended with SHAM and 10 ppm azoxystrobin. All 20 isolates developed colonies on YMA plates lacking azoxystrobin, and treatments produced identical results across three replicates. These results are consistent with findings of higher levels of azoxystrobin resistance in G143A mutants compared to wild types in European populations (1). Isolates from HF and NVF differ in their previous exposure to QoI fungicides. The majority of the wheat area at HF is planted to breeding plots that are not sprayed with fungicide. Plots at NVF were planted in a commercial wheat field in a county where most wheat fields were treated with two to three applications of strobilurins each year over the past 4 years. Future monitoring for G143A mutants of Z. tritici throughout its range in North America will be necessary to assess whether strobilurin resistance will spread via wind-dispersal of ascospores or emerge de novo in treated fields. In Europe, stobilurins were first applied to wheat in 1996. G143A mutants of Z. tritici emerged de novo several times (4) and were widespread by 2007. References: (1) B. A. Fraaje et al. Phytopathology 95:933, 2005. (2) J. A. LaMondia. Tob. Sci. 49:1, 2012. (3) E. S. Orton et al. Mol. Plant Pathol. 12:413, 2011. (4) S. F. F. Torriani et al. Pest Manag. Sci. 65:155, 2008.

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Temporal Changes in Sensitivity of Zymoseptoria tritici Field Populations to Different Fungicidal Modes of Action

Agriculture ◽

10.3390/agriculture11030269 ◽

2021 ◽

Vol 11 (3) ◽

pp. 269

Author(s):

Tim Birr ◽

Mario Hasler ◽

Joseph-Alexander Verreet ◽

Holger Klink

Keyword(s):

Fungal Growth ◽

Temporal Changes ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Significant Shift ◽

Zymoseptoria Tritici ◽

Wheat Cultivation ◽

Dmi Fungicides ◽

Increased Sensitivity ◽

Disease Pressure

Septoria tritici blotch (STB; Zymoseptoria tritici), one of the most important foliar diseases in wheat, is mainly controlled by the intensive use of fungicides during crop growth. Unfortunately, Z. tritici field populations have developed various extents of resistance to different groups of fungicides. Due to the complete resistance to quinone outside inhibitors (QoIs), fungicidal control of STB relies mainly on demethylation inhibitors (DMIs) and succinate dehydrogenase inhibitors (SDHIs) as well as multi-site inhibitors. In this study, temporal changes in the sensitivity of Z. tritici to selected DMIs (tebuconazole, propiconazole, prothioconazole, prochloraz), SDHIs (boscalid, bixafen), and multi-site inhibitors (chlorothalonil, folpet) were determined in microtiter assays using Z. tritici field populations isolated in 1999, 2009, 2014, and 2020 in a high-disease-pressure and high-fungicide-input area in Northern Germany. For the four tested DMI fungicides, a significant shift towards decreasing sensitivity of Z. tritici field populations was observed between 1999 and 2009, whereby concentrations inhibiting fungal growth by 50% (EC50) increased differentially between the four DMIs. Since 2009, EC50 values of tebuconazole, propiconazole, and prochloraz remain stable, whereas for prothioconazole a slightly increased sensitivity shift was found. A shift in sensitivity of Z. tritici was also determined for both tested SDHI fungicides. In contrast to DMIs, EC50 values of boscalid and bixafen increased continuously between 1999 and 2020, but the increasing EC50 values were much smaller compared to those of the four tested DMIs. No changes in sensitivity of Z. tritici were observed for the multi-site inhibitors chlorothalonil and folpet over the last 21 years. The sensitivity adaptation of Z. tritici to both groups of single-site inhibitors (DMIs, SDHIs) mainly used for STB control represents a major challenge for future wheat cultivation.

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

10.1101/130393 ◽

2017 ◽

Cited By ~ 1

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.

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

Irish Journal of Agricultural and Food Research ◽

10.2478/ijafr-2019-0004 ◽

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.

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

10.19103/as.2021.0092.12 ◽

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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