Adaptive evolution in virulence effectors of the rice blast fungus Pyricularia oryzae

Le Naour-Vernet Marie, Charriat Florian, Gracy Jérôme, Cros-Arteil Sandrine, Ravel Sébastien, Meusnier Isabelle, Padilla André, Kroj Thomas, Cesari Stella, Gladieux Pierre. 2023. Adaptive evolution in virulence effectors of the rice blast fungus Pyricularia oryzae. In : 12th International Congress of Plant Pathology (ICPP 2023): One health for all plants, crops and trees. Book of abstracts. ISPP, SFP. Lyon : ISPP, Résumé, 318-319. International Conference on Plant Pathology (ICPP 2023). 12, Lyon, France, 20 Août 2023/25 Août 2023.

Résumé : Plant pathogens secrete proteins called effectors that target host cellular processes to promote disease. Recently, structure-based clustering has identified several families of fungal effectors that share a conserved three-dimensional structure despite remarkably variable amino-acid sequences and surface properties. To explore the selective forces that underlie the sequence variability of structurallyanalogous effectors, we focused on MAX effectors, a structural family of effectors that are major determinants of virulence in the rice blast fungus Pyricularia oryzae. Using structureinformed gene annotation, we identified 58 to 78 MAX effector genes per genome in a set of 120 isolates representing seven host-associated lineages. The expression of MAX effector genes was primarily restricted to the early biotrophic phase of infection and strongly influenced by the host plant. Pangenome analyses of MAX effectors demonstrated extensive presence/absence polymorphism and identified several candidate gene loss events possibly involved in host range adaptation. MAX effectors displayed high levels of standing variation and high rates of non-synonymous substitutions, pointing to widespread positive selection shaping their molecular diversity. Our work demonstrates that MAX effectors represent a highly dynamic compartment of the genome of P. oryzae, and suggests that MAX effectors are key players in molecular coevolutionary interactions with plant hosts.

Auteurs et affiliations

• Le Naour-Vernet Marie, Université de Montpellier (FRA)
• Charriat Florian, CIRAD-BIOS-UMR ASTRE (FRA)
• Gracy Jérôme, CNRS (FRA)
• Cros-Arteil Sandrine, INRAE (FRA)
• Ravel Sébastien, CIRAD-BIOS-UMR PHIM (FRA) ORCID: 0000-0001-6663-782X
• Meusnier Isabelle, INRAE (FRA)
• Padilla André, CNRS (FRA)
• Kroj Thomas, INRAE (FRA)
• Cesari Stella, INRAE (FRA)
• Gladieux Pierre, INRAE (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/609799/)

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