The Magnaporthe oryzae MAP kinase Pmk1 regulates polycomb repressive complex 2 to reprogram genes expression for biotrophic growth

Biotrophic and hemibiotrophic fungi have evolved the ability to colonize living plant cells, but how they establish biotrophic growth by remodeling gene expression is poorly understood. By using in planta invasive hyphae (IH) of Magnaporthe oryzae to perform an integrated Chromatin immunoprecipitation sequencing (ChIPseq) and RNA-seq analysis, combining with biological and cellular analyses, we found Polycomb repressive complex 2 (PRC2)-mediated epigenetic repression plays a key role in regulating biotrophic growth. ChIPseq for biotrophic IH samples identified 1701 PRC2 target genes. RNA-seq analysis showed that expression of 462 PRC2 target genes were up-regulated in the {Delta}suz12 mutant, while 82 were down-regulated, indicating a major role of PRC2 in gene repression of IH. During biotrophic growth, PRC2 repressed fungal cell wall synthesis genes and extracellular enzyme genes required for penetration, and secondary metabolites biosynthesis genes required for necrotrophic growth. A great number of effector-encoding genes were repressed by PRC2, which were highly expressed during penetration stage, suggesting PRC2 coordinates biotrophic growth by regulating effector suppression for immune evasion. This regulation was finely coordinated by Pmk1, through regulating phosphorylation, nuclear localization and protein abundance of Suz12. Our results indicate that the Pmk1-PRC2 regulatory module is required for gene remodeling to facilitate biotrophic growth in M. oryzae.