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The International Symposium on Cereal Leaf Blights is a prominent conference in the field, held every 2-3 years. Jointly organised by ETH Zurich and the University of Neuchâtel, the 2024 conference gathered experts, researchers, and students worldwide to discuss the latest developments and challenges in cereal leaf blights. The focus was particularly on Zymoseptoria, Pyrenophora affecting wheat and barley, and Parastagonospora diseases, covering diverse topics and speakers, from functional genomics and gene cloning to remote sensing. Other pathogens such as stem rust and Wheat blast, which threaten global wheat production, were also addressed.
The meeting featured sessions with lead speakers and selected abstract-based presentations, as well as two afternoon poster sessions. The opening included a keynote presentation titled ‘Insights from a Gall-Inducing Fungus’ by Professor Armin Djamei (University of Bonn). Sessions delved into leaf spot diseases, ranging from genetic analysis to defining effectors in barley net blotch and tan spots. The subsequent four days covered various scientific sessions encompassing effector biology, fungicide resistance, R gene cloning, leaf microbiota, and the use of remote sensing approaches in field phenotyping.
Several notable presentations stood out. Due to space constraints, I will highlight a few examples: Victor Flores Nuñez from Christian-Albrechts University (Kiel, Germany) investigated the dynamics of leaf microbiomes in wild grasses and their molecular interactions with host-specific lineages of Zymoseptoria. He revealed that healthy and diseased plants assemble distinct microbiomes, with wild plants harboring a higher diversity of bacterial taxa exhibiting antifungal activity. Competition assays showed that Zymoseptoria inhibits a broader subset of wheat-associated bacteria compared to those associated with wild hosts.
Another significant talk was given by Dr Megan McDonald from the University of Birmingham (UK). Her presentation focused on the 14 kbp ToxhAT transposon, which facilitates horizontal transfer of necrotrophic effector genes among wheat-infecting fungal species Parastagonospora nodorum, Pyrenophora tritici-repentis, and Bipolaris sorokiniana. Using long-read de novo assembly of eight novel and one previously published B. sorokiniana isolates, including identification of “TA” target site duplications, she confirmed that the “starship” transposon acts as a sanctuary for the movement of the virulence factor ToxA.
Moreover, Dr Frederic Suffert from INRA (France) presented the impact of sexual reproduction on the adaptive dynamics of Z. tritici populations driven by R-AVR interactions. He demonstrated that Stb genes do not fully limit sexual reproduction and under certain conditions, crosses could either suppress resistance breakdown by maintaining the frequency of virulent strains below a critical threshold or conversely, increase it, potentially leading to the emergence of multi-virulent strains. In this context, managing smart mixtures could offer a solution depending on cultivar choice, mixture composition, disease pressure, and initial virulent strain frequency.
Dr Andrea Sánchez-Vallet from Centro de Biotecnología y Genómica de Plantas (CBGP, Spain) gave an excellent presentation regarding the contribution of effectors in Z. tritici triggering host resistance and in interacting with fungal endophytes, and the role of effector gene regulation in host evasion.
I also had the privilege of presenting as a lead speaker, sharing my research on accelerating the identification of resistance to major wheat fungal threats in Tunisia with a focus on Septoria tritici blotch, Tan spot and stem rust diseases on wheat.
The conference closed with engaging lectures from distinguished experts such as Professors Gert Kema, Steve Goodwin, Tim Friesen, Richard Oliver, Bruce McDonald, and March-Henri Lebrun. They reflected on their careers spanning several decades, sharing personal experiences, anecdotes, and real-life examples. Finally, the symposium concluded with a keynote presentation on ‘Mycorrhizas and Microbiome Management for Sustainable Agriculture’ by Professor Marcel van der Heijden (University of Zurich).
In addition to the scientific program, we enjoyed social events including a welcome reception, an evening walking city tour, culminating in a conference dinner, and an optional boat trip. Overall, the blend of scientific exchange and collaboration opportunities made this a highly enriching experience that will greatly benefit my future research. I am immensely grateful to the BSPP for this opportunity.
Dr Sarrah Ben M’Barek
Regional Field Crops Research Center of Béja, Tunisia
