06 March 2024 – 11:00 ET
Investigating complex interactions between effector genes and the chromatin-based control of their expression in the plant pathogenic fungus Leptosphaeria maculans

During infection, pathogens, including fungi, secrete an arsenal of molecules, collectively called effectors, key elements of pathogenesis that modulate innate immunity of the plant and facilitate infection. Effectors have a dual role in microbe-plant interactions, both targeting plant components and being targeted by resistance (R) proteins and then termed avirulence (AVR) proteins. Leptosphaeria maculans is responsible for one of the most devastating disease of oilseed rape (Brassica napus). The sequencing of its genome revealed a bipartite structure, alternating gene rich GC-equilibrated regions and gene poor AT-rich regions made up of mosaics of transposable elements. The AT-rich regions encompass one third of the genome and are enriched in putative effector genes including cloned AVR genes that present the same expression pattern (no or a low expression level during in vitro growth and a strong over-expression during all the biotrophic stages of infection). We are currently investigating: (i) the involvement of L. maculans effectors in pathogenicity and their complex interactions with R proteins using structural biology and functional genomics; (ii) the regulation of L. maculans effector genes, including the chromatin-based and transcriptional control of their expression.