EvolMAX · Molecular determinants of host adaptation in fungal-plant pathogens: origins and evolution of virulence effectors by genomic, phylogenetic and association mapping studies

Molecular determinants of host adaptation in fungal-plant pathogens: origins and evolution of virulence effectors by genomic, phylogenetic and association mapping studies

Emerging fungal pathogens are an increasing threat to ecosystems, global health, and food security. Increasing global trade, expansion of monocultures and climate change facilitate more pathogen encounters and opportunities for infecting new potential hosts. Host shifts and plant resistance breakdowns largely contribute to the emergence of new plant pathogens, resulting in major diseases outbreaks and yield losses. Despite the growing number of studies on invasive fungi, our understanding of how these fungal pathogens evolve, switch hosts and become virulent is far from complete. Host shifts are thought to be mediated by molecular changes at small proteins secreted by pathogens. These proteins, known as effectors, manipulate key plant defence mechanisms, promote infection and represent key elements of fungal virulence. Knowledge of the mechanisms underlying rapid evolution of pathogens and their change in virulence during host shifts is crucial to design efficient and sustainable disease management strategies. The proposed research focus on a major model for the study of plant-pathogen interactions, the ascomycete fungus Pyricularia oryzae (syn. Magnaporthe oryzae). This destructive fungal pathogen, causing up to 30% of rice production losses globally, infects diverse cereals and grasses. The specific objectives of EvolMAX were to: • Identify virulence genes of P. oryzae involved in adaptation to new rice varieties. • Investigate effector repertoire diversity and evolution in P. oryzae lineages associated with various cereal hosts to better understand host shifts. The proposed research thus focused on processes related to host adaptation within lineages, and at wider scales between lineages and species. At the rice variety level, we identified two major candidate genes involved in virulence for three rice varieties using genome-wide association mapping. At wider scale, we compiled the most unique and robust dataset of all P. oryzae available genomes infecting all host species to understand the molecular basis of host adaptation.

Data: CORDIS, © European Union