Person: Heß, Michael
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Veröffentlichung Analysis of archive samples of spring and winter barley support an increase in individual Fusarium species in Bavarian barley grain over the last decades(2019) Hofer, Katharina; Heß, Michael; Hückelhoven, RalphA broad range of different Fusarium (F.) species is associated with Fusarium head blight (FHB) on barley and the corresponding negative effects in downstream processing of barley grain in food and feed production. Previous studies highlight the significance of the wheat-relevant and well-studied species F. graminearum as well as less prominent species including F. culmorum, F. avenaceum, F. tricinctum, F. langsethiae, F. sporotrichioides, F. poae, and others. In this context, prevalent climate and cultivation conditions were shown to determine disease severity as well as dominance of certain species within the Fusarium pathogen complex. To gain further insight into possible historic developments of FHB, the annual occurrence of currently relevant Fusarium species was analyzed in Bavarian archive samples of winter (from 1958 to 2010) and spring barley (from 1965 to 2010) using species-specific quantitative polymerase chain reaction. Although DNA contents varied between samples of individual years, data suggest a general increase in Fusarium incidence, particularly in spring barley. Comparing pathogen complexes, we observed not only continuous dominance of F. graminearum in winter barley, but also an increasing relevance of this species in spring barley. The rising Fusarium incidence over time generally coincides with climate change related factors like increasing temperatures. However, it may furthermore be linked to changing cultivation methods and intensified maize production. This study therefore exhibits the dynamic complexity of barley grain contamination with Fusarium spp., which should be taken into account for future disease management. Quelle: https://link.springer.comVeröffentlichung Influence of Fusarium avenaceum infections on barley malt: Monitoring changes in the albumin fraction of barley during the malting process(2019) Geißinger, Cajetan; Whitehead, Iain; Heß, Michael; Hofer, KatharinaFusarium spp. are ubiquitous field pathogens, which are known to affect quality characteristics of cereals. Infections with Fusarium pathogens in brewing cereals are problematic and augur for a poor malt quality. The negative effects of Fusarium infections are various. Besides causing agronomic losses, kernel discoloration, and the production of several mycotoxins, Fusarium spp. are known to enhance the proteolytic activity of infected barley malt. Enhanced proteolysis can be observed in higher values in free amino nitrogen (FAN) as well as in soluble nitrogen. Previous studies showed that, in recent crop years, the predominant Fusarium spp. detected in European malt was F. avenaceum. This study focuses on the changes in the albumin fraction during the malting process of barley samples artificially infected with F. avenaceum in comparison to uninfected control samples. The barley samples were grown under controlled conditions in a greenhouse, and two different sample types were studied: One was not infected with Fusarium spores whereas the other sample was inoculated during anthesis with a spore suspension of F. avenaceum. Malting trials were carried out in a micromalting facility under defined conditions. To monitor the changes in protein profiles due to Fusarium infection, samples were analyzed at different stages of the malting process: barley (raw grain), poststeeping, postgermination, and postkilning. To evaluate the changes in the protein composition, different fractionation techniques (Osborne fractionation, isoelectric focusing, and capillary gel electrophoresis) were utilized. The albumins of the Osborne fractionation were further analyzed as they represent the main metabolically active proteins. Protein maps of the different malting steps were plotted with a custom-programmed visualization tool for comparing the infected and uninfected samples at each malting step. The results elucidate the changes in the albumin fraction during the malting process and reveal the influence of Fusarium infection on the albumin composition of barley, barley malt, and the intermediate products of malting. © 2019 Elsevier B.V. All rights reserved.Veröffentlichung Ramularia nachhaltig bekämpfen durch Erkenntnisse aus der Genom-Analyse(2019) Heß, MichaelVeröffentlichung Culture conditions influence conidial production by the barley pathogen Ramularia collo-cygni(2019) Sghyer, Hind; Heß, MichaelThe fungus Ramularia collo-cygni is the causal agent of the Ramularia leaf spot (RLS) disease of barley (Hordeum vulgare). Despite having been described over 100 years ago, our knowledge of the life cycle and epidemic development of R. collo-cygni is limited. To learn more about its epidemiology, inoculation techniques are among the major research needs since standardised inoculation procedures must be available to mimic natural infection of the pathogen under controlled conditions. The present study was conducted to obtain an insight into various factors affecting the growth and sporulation of R. collo-cygni in axenic culture. The fungus was cultured on four different media and subjected to two light regimens to determine conditions favourable for its growth and sporulation. We showed that conidial production can be enhanced by growing R. collo-cygni on barley straw agar, a medium that mimics the plant host, under white light, or on quarter-strength potato dextrose agar supplemented with V8 juice agar under ultraviolet-C light, depending on the fungal isolate. To verify the infection potential of the spores produced in axenic culture, an inoculation trial was performed. R. collo-cygni spore-inoculated barley plants accumulated fungal biomass, demonstrating successful infection. Quelle: https://link.springer.comVeröffentlichung Population genetic structure of Microdochium majus and Microdochium nivale associated with foot rot of cereals in the Czech Republic and adaptation to penthiopyrad(2019) Matusinsky, Pavel; Heß, Michael; Svobodova-Leisova, Leona; Svačinová, IvanaMicrodochium nivale and Microdochium majus cause brown foot rot and snow mould in cereals. The aim of the present study was to evaluate the population genetic structure of Microdochium spp. associated with foot rot of wheat in the Czech Republic and the reaction of that population to the succinate dehydrogenase inhibitor (SDHI) fungicide penthiopyrad. Using amplified fragment length polymorphism (AFLP) analysis to examine genetic structure, agar dilution to measure inhibitory effect, and various statistical methods to analyse populations, two genetic populations were found corresponding to the species Microdochium majus and M. nivale and restricted gene flow in populations between years was determined. This study demonstrates for the first time the occurrence of SDHI-insensitive reaction in populations of M. nivale and M. majus. Low sensitivity was identified in both species, but it was observed more frequently in M. majus populations. Quelle: https://link.springer.comVeröffentlichung Geht es auch ohne Chemie?(2019) Heß, MichaelDie chemische Saatgutbeize ist das einfachste und sicherste Verfahren. Wenn sie aber nicht mehr wirkt und weiterhin Mittel verloren gehen? Michael Hess diskutiert physikalische und biologische Alternativen. Quelle: https://www.dlg-mitteilungen.deVeröffentlichung The current epidemic of the barley pathogen Ramularia collo-cygni derives from a population expansion and shows global admixture(2019) Stam, Remco; Heß, Michael; Sghyer, Hind; Tellier, AurélienRamularia leaf spot is becoming an ever-increasing problem in main barley-growing regions since the 1980s, causing up to 70% yield loss in extreme cases. Yet, the causal agent Ramularia collo-cygni remains poorly studied. The diversity of the pathogen in the field thus far remains unknown. Furthermore, it is unknown to what extent the pathogen has a sexual reproductive cycle. The teleomorph of R. collo-cygni has not been observed. To study the genetic diversity of R. collo-cygni and get more insights in its biology, we sequenced the genomes of 19 R. collo-cygni isolates from multiple geographic locations and diverse hosts. Nucleotide polymorphism analyses of all isolates shows that R. collo-cygni is genetically diverse worldwide, with little geographic or host specific differentiation. Next, we used two different methods to detect signals of recombination in our sample set. Both methods find putative recombination events, which indicate that sexual reproduction happens or has happened in the global R. collo-cygni population. Lastly, we used these data on recombination to perform historic population size analyses. These suggest that the effective population size of R. collo-cygni decreased during the domestication of barley and subsequently grew with the rise of agriculture. Our findings deepen our understanding of R. collo-cygni biology and can help us to understand the current epidemic. We discuss how our findings support possible global spread through seed transfer, and we highlight how recombination, clonal spreading, and lack of host specificity could amplify global epidemics of this increasingly important disease and suggest specific approaches to combat the pathogen. © 2019 The American Phytopathological SocietyVeröffentlichung Schneeschimmel auch auf Blatt und Ähre!(2019) Heß, MichaelDie Beize bietet nicht immer Schutz: Microdochium-Erreger verursachten in den letzten Jahren immer häufiger Blattsymptome. Und zwar umso häufiger, je besser eine Septoria-Bekämpfung funktioniert hat. Michael Heß erklärt die Zusammenhänge. Quelle: https://www.dlg-mitteilungen.deVeröffentlichung Septoria- oder Microdochiumbefall oder beides?(2019) Heß, Michael