Understanding plant-pathogen interactions in Septoria tritici blotch infection of cereals

2021 ◽  
pp. 263-302
Author(s):  
Y. Petit-Houdenot ◽  
◽  
M.-H. Lebrun ◽  
G. Scalliet ◽  
◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Resistance Management ◽  
Infection Process ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Wheat Cultivars ◽  
Molecular Studies ◽  
The Subject ◽  
Asymptomatic Phase ◽  
Plant Pathogen Interactions

Zymoseptoria is a major fungal pathogen of wheat, responsible for the Septoria Tritici Blotch (STB) disease. Recently, STB has been the subject of intensive molecular studies. Notably, massive transcriptomic analyses have helped to explore this particular bi-phasic (asymptomatic/necrotrophic) infection process. Cytological analyses have also improved our understanding of the asymptomatic phase. These advances suggest that Zymoseptoria behaves as a hemi-biotrophic fungus, acting like an endophyte during its asymptomatic phase. STB is still difficult to control. The emergence of fungicide-resistant isolates has reduced the efficacy of many fungicides requiring the development of novel fungicides and methods to counteract/reduce fungicide resistance. Likewise, because Stb-resistant wheat cultivars have all been successively defeated by virulent isolates, there is a need to identify new resistance genes in wheat, and to develop better disease resistance management methods (pyramiding, mixture/alternation) to sustainably control this pathogen.

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 Temporal Dynamics and Spatial Variation of Azoxystrobin and Propiconazole Resistance in Zymoseptoria tritici: A Hierarchical Survey of Commercial Winter Wheat Fields in the Willamette Valley, Oregon

2017 ◽  
Vol 107 (3) ◽  
pp. 345-352 ◽  
Author(s):  
Christina H. Hagerty ◽  
Nicole P. Anderson ◽  
Christopher C. Mundt
Keyword(s):  
Winter Wheat ◽  
Spatial Variation ◽  
Fungicide Resistance ◽  
Temporal Dynamics ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Willamette Valley ◽  
Zymoseptoria Tritici ◽  
Quinone Outside Inhibitor ◽  
Inhibitor Resistance

Fungicide resistance can cause disease control failure in agricultural systems, and is particularly concerning with Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat. In North America, the first quinone outside inhibitor resistance in Z. tritici was discovered in the Willamette Valley of Oregon in 2012, which prompted this hierarchical survey of commercial winter wheat fields to monitor azoxystrobin- and propiconazole-resistant Z. tritici. Surveys were conducted in June 2014, January 2015, May 2015, and January 2016. The survey was organized in a hierarchical scheme: regions within the Willamette Valley, fields within the region, transects within the field, and samples within the transect. Overall, frequency of azoxystrobin-resistant isolates increased from 63 to 93% from June 2014 to January 2016. Resistance to azoxystrobin increased over time even within fields receiving no strobilurin applications. Propiconazole sensitivity varied over the course of the study but, overall, did not significantly change. Sensitivity to both fungicides showed no regional aggregation within the Willamette Valley. Greater than 80% of spatial variation in fungicide sensitivity was at the smallest hierarchical scale (within the transect) of the survey for both fungicides, and the resistance phenotypes were randomly distributed within sampled fields. Results suggest a need for a better understanding of the dynamics of fungicide resistance at the landscape level.

scholarly journals Baseline and Temporal Changes in Sensitivity of Zymoseptoria tritici Isolates to Benzovindiflupyr in Oregon, U.S.A., and Cross-Sensitivity to Other SDHI Fungicides

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 169-174
Author(s):  
Christina H. Hagerty ◽  
Ann M. Klein ◽  
Catherine L. Reardon ◽  
Duncan R. Kroese ◽  
Caroline J. Melle ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Fungal Growth ◽  
Careful Consideration ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Willamette Valley ◽  
Active Ingredients ◽  
Effective Population ◽  
Zymoseptoria Tritici ◽  
Cross Sensitivity

Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB), a disease of wheat (Triticum aestivum) that results in significant yield loss worldwide. Z. tritici’s life cycle, reproductive system, effective population size, and gene flow put it at high likelihood of developing fungicide resistance. Succinate dehydrogenase inhibitor (SDHI) fungicides (FRAC code 7) were not widely used to control STB in the Willamette Valley until 2016. Field isolates of Z. tritici collected in the Willamette Valley at dates spanning the introduction of SDHI (2015 to 2017) were screened for sensitivity to four SDHI active ingredients: benzovindiflupyr, penthiopyrad, fluxapyroxad, and fluindapyr. Fungicide sensitivity changes were determined by the fungicide concentration at which fungal growth is decreased by 50% (EC50) values. The benzovindiflupyr EC50 values increased significantly, indicating a reduction in sensitivity, following the adoption of SDHI fungicides in Oregon (P < 0.0001). Additionally, significant reduction in cross-sensitivity among SDHI active ingredients was also observed with a moderate and significant relationship between penthiopyrad and benzovindiflupyr (P = 0.0002) and a weak relationship between penthiopyrad and fluxapyroxad (P = 0.0482). No change in cross-sensitivity was observed with fluindapyr, which has not yet been labeled in the region. The results document a decrease in SDHI sensitivity in Z. tritici isolates following the introduction of the active ingredients to the Willamette Valley. The reduction in cross-sensitivity observed between SDHI active ingredients highlights the notion that careful consideration is required to manage fungicide resistance and suggests that within-group rotation is insufficient for resistance management.

scholarly journals Use of Detached Seedling Leaf Test to Evaluate Wheat Resistance to Septoria Tritici Blotch

2011 ◽  
Vol 41 (No. 3) ◽  
pp. 112-116 ◽  
Author(s):  
L. Věchet ◽  
M. Vojáčková
Keyword(s):  
Field Tests ◽  
Resistance Breeding ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Wheat Cultivars ◽  
Breeding Lines ◽  
Winter Wheat Cultivars ◽  
Modern Wheat ◽  
Wheat Wild Relatives ◽  
Seedling Leaf

Two experimental sets of selected winter wheat cultivars, breeding lines, old Czech and Slovak landraces and wheat wild relatives were infected with three isolates (R-116, UH-105, BR-331) of Mycosphaerella graminicola (anamorph Septoria tritici) isolated in the Czech Republic. Groups of cultivars with different disease severity to all three isolates of the pathogen were found. Differences between old Czech and Slovak landraces and wild wheat relatives were larger than between modern wheat cultivars and breeding materials. In experiment one the isolate BR-331 differed significantly from the other two isolates in virulence to the tested modern wheat cultivars and breeding lines. The method is considered as suitable for preliminary screening in wheat resistance breeding or phytopathological testing and as a complement to field tests. &nbsp; &nbsp;

scholarly journals Quantification of In Planta Zymoseptoria tritici Progression Through Different Infection Phases and Related Association with Components of Aggressiveness

2020 ◽  
Vol 110 (6) ◽  
pp. 1208-1215 ◽  
Author(s):  
Atikur Rahman ◽  
Fiona Doohan ◽  
Ewen Mullins
Keyword(s):  
Growth Rate ◽  
Latent Period ◽  
Host Resistance ◽  
Infection Process ◽  
Early Infection ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
In Planta ◽  
Zymoseptoria Tritici ◽  
Host Interaction

In planta growth of Zymoseptoria tritici, causal agent of Septoria tritici blotch of wheat, during the infection process has remained an understudied topic due to the long symptomless latent period before the emergence of fruiting bodies. In this study, we attempted to understand the relationship between in planta growth of Z. tritici relative to the primary components of aggressiveness, i.e., latent period and pycnidia coverage in regard to contrasting host resistance. We tested isolates collected from Ireland against the susceptible cultivar Gallant and cultivar Stigg, which has strong partial resistance. A clear isolate−host interaction effect (F = 3.018; P = 0.005, and F = 6.008; P < 0.001) for latent period and pycnidia coverage, respectively, was identified. Furthermore, during the early infection phase of latency from 5 to 11 days postinoculation (dpi), in planta growth rate of fungal biomass was significantly (F = 30.06; P < 0.001) more affected by host resistance than isolate specificity (F = 1.27; P = 0.27), indicating the importance of host resistance in the early infection phase. In planta Z. tritici growth rates in cultivar Gallant spiked between 11 and 16 dpi followed by a continuous fall onward, whereas in cultivar Stigg it was slowly progressive in nature. From correlation and regression analysis, we found that the in planta growth rate preceding the average latent period of cultivar Gallant has more influence on latency duration and pycnidia production. Likewise, correlation between component of aggressiveness and in planta growth rate of pathogen supports our understanding of aggressiveness to be driven by the pathogen’s multiplication capacity within host tissue.

Relationship of the severity of Septoria tritici blotch of wheat to sowing time, rainfall at heading and average susceptibility of wheat cultivars in the area

1990 ◽  
Vol 41 (2) ◽  
pp. 307 ◽  
Author(s):  
GM Murray ◽  
RH Martin ◽  
BR Cullis
Keyword(s):  
New South ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Daily Maximum ◽  
Wheat Cultivars ◽  
South Wales ◽  
Before And After ◽  
Rainy Days

The severity of epidemics of Septoria tritici blotch (STB) in wheat, caused by Mycosphaerella graminicola, was recorded for a 38-year period at Temora in southern New South Wales. The disease was rated as severe in 11 years, moderate in 11 and nil to light in 15, while very wet conditions prevented sowing in one year. The correlation of disease severity (S, where 0 =nil, 7 =very severe) with environmental and management factors was examined: the correlation was positive with days from sowing to heading and with rainfall ( R-4W , R+4W, mm) and the number of rainy days in the 4-week periods before and after heading; negative with the time of sowing (DS, day of year) and with mean daily maximum temperature in the 4-week periods before and after heading. Days from sowing to heading were negatively correlated with sowing day, and rainy days and mean daily maximum temperature were correlated with total rainfall in the same time period. Addition of these terms did not significantly improve the prediction of severity. The cumulative sum of the recursive residuals from this regression showed a trend with time that was associated with the average susceptibility (SAV, where 1 =highly resistant, 7 =extremely susceptible) of wheat cultivars to STB grown in the district in the previous year. The second model showed that the reduction of the average susceptibility of cultivars grown in an area will reduce the severity of STB. It provided justification for minimum disease standards for cultivars to be grown where STB is potentially severe. Further, it explained the distribution of severity of STB in New South Wales.

scholarly journals Ranking Quantitative Resistance to Septoria tritici Blotch in Elite Wheat Cultivars Using Automated Image Analysis

2018 ◽  
Vol 108 (5) ◽  
pp. 568-581 ◽  
Author(s):  
Petteri Karisto ◽  
Andreas Hund ◽  
Kang Yu ◽  
Jonas Anderegg ◽  
Achim Walter ◽  
...  
Keyword(s):  
Image Analysis ◽  
Quantitative Resistance ◽  
Major Gene ◽  
Growing Season ◽  
Automated Image Analysis ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Wheat Cultivars ◽  
Zymoseptoria Tritici ◽  
Breeding Programs

Quantitative resistance is likely to be more durable than major gene resistance for controlling Septoria tritici blotch (STB) on wheat. Earlier studies hypothesized that resistance affecting the degree of host damage, as measured by the percentage of leaf area covered by STB lesions, is distinct from resistance that affects pathogen reproduction, as measured by the density of pycnidia produced within lesions. We tested this hypothesis using a collection of 335 elite European winter wheat cultivars that was naturally infected by a diverse population of Zymoseptoria tritici in a replicated field experiment. We used automated image analysis of 21,420 scanned wheat leaves to obtain quantitative measures of conditional STB intensity that were precise, objective, and reproducible. These measures allowed us to explicitly separate resistance affecting host damage from resistance affecting pathogen reproduction, enabling us to confirm that these resistance traits are largely independent. The cultivar rankings based on host damage were different from the rankings based on pathogen reproduction, indicating that the two forms of resistance should be considered separately in breeding programs aiming to increase STB resistance. We hypothesize that these different forms of resistance are under separate genetic control, enabling them to be recombined to form new cultivars that are highly resistant to STB. We found a significant correlation between rankings based on automated image analysis and rankings based on traditional visual scoring, suggesting that image analysis can complement conventional measurements of STB resistance, based largely on host damage, while enabling a much more precise measure of pathogen reproduction. We showed that measures of pathogen reproduction early in the growing season were the best predictors of host damage late in the growing season, illustrating the importance of breeding for resistance that reduces pathogen reproduction in order to minimize yield losses caused by STB. These data can already be used by breeding programs to choose wheat cultivars that are broadly resistant to naturally diverse Z. tritici populations according to the different classes of resistance.

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