Magnaporthe oryzae is one of the most devastating pathogenic fungi that affects a wide range of cereal plants, especially rice. Rice blast disease causes substantial economic losses around the globe. The M. oryzae genome was first sequenced at the beginning of this century and was recently updated with improved annotation and completeness. In this review, key molecular findings on the fungal development and pathogenicity mechanisms of M. oryzae are summarized, focusing on fully characterized genes based on mutant analysis. These include genes involved in the various biological processes of this pathogen, such as vegetative growth, conidia development, appressoria formation and penetration, and pathogenicity. In addition, our syntheses also highlight gaps in our current understanding of M. oryzae development and virulence. We hope this review will serve to improve a comprehensive understanding of M. oryzae and assist disease control strategy designs in the future.

Sclerotinia sclerotiorumcauses white mold or stem rot in a broad range of economically important plants, bringing significant yield losses worldwide. Host-induced gene silencing (HIGS) has been showing promising effects in controlling many fungal pathogens, includingS. sclerotiorum. However, molecular genetic understanding of signaling pathways involved in its development and pathogenicity is needed to provide effective host-induced gene silencing (HIGS) targets for disease control. Here, by employing a forward genetic screen, we characterized an evolutionarily conserved mitogen-activated protein kinase (MAPK) cascade inS. sclerotiorum, consisting of SsSte50-SsSte11-SsSte7-Smk1, controlling mycelial growth, sclerotia development, compound appressoria formation, virulence, and hyphal fusion. Moreover, disruption of the putative downstream transcription factor SsSte12 led to normal sclerotia but aberrant appressoria formation and host penetration defects, suggestive of diverged regulation downstream of the MAPK cascade. Most importantly, targeting ofSsSte50using host-expressed HIGS double stranded RNA resulted in largely reduced virulence ofS. sclerotiorumonNicotiana benthamianaleaves. Therefore, this MAPK signaling cascade is generally needed for its growth, development, and pathogenesis, and is an ideal HIGS target for mitigating economic damages caused byS. sclerotioruminfection.

No abstract